POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

ALCOHOLIC LIVER DISEASE

1089-3261/98 $8.00

+

.OO

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE Kevin D. Mullen, MB, FRCPI, and S. Dasarathy, MD, DM

Alcoholic liver disease (ALD) is a common clinical problem. The various stages of alcoholic liver injury include alcoholic fatty liver, alcoholic hepatitis, and cirrhosis of the l i ~ e r . ~It~has ,*~ been suggested that only 8% to 20% of longterm alcohol abusers develop alcoholic cirrhosis.16,45, Iz7 The goals of therapy in ALD are shown below. Avoid alcohol Improve nutrition Treat hepatic injury Prevent progression to cirrhosis Avoid complications of severe liver disease Evaluate presence of coexisting hepato-injurious factors Attempt reversal of cirrhosis Promote hepatic regeneration and function Consider liver transplantation in end-stage liver disease Long-term outcome in these patients depends on three major factorsdegree of continued alcohol abuse, severity of underlying liver damage and additional hepato-injurious factors (hepatitis C virus [HCV], acetaminophen).I2, 43, lZ6The acute mortality of acute alcoholic hepatitis is 20% to 60%.12Progression to cirrhosis may occur despite abstinence but usually arises in subjects who continue to abuse Understanding the biomolecular basis of liver injury has advanced significantly in the past decade. The importance of acetaldehyde, free radicals and acetaldehyde-protein adduct antibody reactions has been studied e~tensively.~~, 64, 136 Conventional and potentially beneficial therapies for alcoholic liver disease This paper is supported in part by the National Institutes of Health Grant RolAA10410.

From the MetroHealth Medical Center, Case Western Reserve University (KDM), Cleveland, Ohio; and the All India Institute of Medical Sciences (SD), New Delhi, India

CLINICS IN LTVER DISEASE VOLUME 2 NUMBER 4 * NOVEMBER 1998

851

852

MULLEN & DASARATHY

are based on blocking or attempting to block one or more steps in the proposed pathogenic pathway for alcohol-mediated hepatic injury.80The major steps in alcohol-mediated liver injury are shown in Figure l . l z 7Conventional therapeutic measures for alcoholic hepatitis have included corticosteroids and nutritional rehabilitation.'* Hepatoprotection by hormonal alterations (insulin-glucagon) has not been found to be very beneficial and colchicine may be of some benefit in fibrosis reduction.*O,86 Newer forms of interventions have included measures directed against the free radicals and cellular toxins such as iron overload and nitric oxide deficiency. Other measures have included those against endotoxemia and provision of the metabolite intermediates that are deficient in hepatocytes injured by 63, These compounds have included pharmacologic agents used in patients with other forms of liver disease, provision of precursors for protective agents via dietary interventions, and many herbal products, the 80, 85, 86 The mechanisms of action of which are not yet clearly under~tood.3~. present review focuses on less conventional agents that have been considered promising in initial clinical trials or have a rationale based on our current understanding of the pathogenesis of alcoholic liver injury.

Antibiotics Calcium channel fl blockers

I

Endotoxemia

Pentoxyfilline

n

TNF alpha cox 2

-

Vasoconstriction

permeability

I

\I Iron overload

U

+Kupffer cells -b

ALCOHOL

+ Acetaldehyde

1

Naftidrofuryl Lipid peroxidation

!I

Nitricoxide

V

NO modifiers

Dietary saturated fat Vitamin E Cyanidanol Silymarin Thioctic acid Lazeroids Flavinoids

Lipid transport LIVERINJURY

U

Bile acids Malotilate Licorice derivatives Figure 1. Current understanding of alcohol-mediated liver disease and the potential levels at which promising agents may benefit in interrupting the cycle of hepatic liver damage. This is necessarily a simplified version and does not include all the steps of alcoholmediated liver injury. The role of stellate cell in the pathogenesis is not represented but may be at the level between the kupffer cell and the hepatocytes. Boxed arrows show potential for intervention. TNF = tumor necrosis factor; Cox = cyclo-oxygenase; NO = nitric oxide.

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

853

New Therapeutic Agents for Alcoholic Liver Disease Hepatocytoprotective agents Ursodeoxycholic acid* Cyanidanol* Alpha-thioctic acid

Silybum marianum* Pentoxifylline* Licorice derivatives Malotilate* Calcium channel blockers* Misoprostolt Special nutrients S-Adenosyl methionhe* Polyunsaturated lecithin* Saturated fat in diett Linoleic acidt L-Cysteinet L-Glycinet Antioxidants Alpha-tocopherol* Lazeroidt Chrysanthemum extractt, kakkelidet, sirepart, propolist Iron chelation Macromolecular desferrioxaminet Anti-endotoxin (antibiotics, others) Ciprofloxacin, polymixin-neomycint Nitric oxide synthase modulaterst Paromycin* Molecular interventions Proline analogues; rHGH* E3330t; prolyl 4 hydroxylase inhibitors Others N-acetyl cysteine* NaftidrofuryP Picrolivt CYP2E1 inhibitorst, Cimetidinet Metadoxine* The agents that have been considered promising in the therapy of ALD may be considered under various categories-agents that have been subjected to randomized trials, those evaluated in open trials, and agents under evaluation in experimental models. Some agents have been evaluated for ALD without definite experimental basis, but have shown promise in therapy for other liver diseases (Tables 1 and 2). Text continued on page 861 *Controlled/uncontrolled trials in humans in addition to animal/experimental studies. tAnimal studies only available. rHGH = recombinant human growth hormone; CYPZEl = cytochrome P4502E1.

Cyanidanol

Tauro UDCA, UDCA

High-dose vitamin E

Polyunsaturated lecithin

Polyenyl phosphatidyl choline

SAMe Nifedepine

Vargo, 1990

Neuman, 1995

Houssein, 1994

Leiber, 1990

Navder, 1997

Leiber, 1990 Cutrin, 1992

+ SAMe

Cyanidanol

Compound Evaluated

Vargo, 1989

Author, Year

Baboon Rats

Rat

Liver injury Liver histology, LFT

Liver biopsy

Hepatic fibrosis, membrane stabilization

Lipid peroxidation, liver pathology

Rats

Baboon

Hepatic enzymes in culture medium. EM: mitochondrial damage

Hepatic morphometry

Hepatic morphometry

Outcome Variables

Human Hep G2 cell lines

Rat

Rat

Model

Table 1. PRODUCTS EVALUATED IN ANIMAL MODELS OF ALCOHOLIC LIVER INJURY

Cyanidanol prevents changes in rnorphometric parameters in hepatic lobules Cyanidanol restored, rnorphometric distortion caused by alcohol Low doses of tauro UDCA and UDCA protect Hep G1 cell lines from alcohol-mediated cytotoxicity. Tauro UDCA more effective than UDCA High-dose vitamin E supplementation reduced lipid peroxidation but had no protective effect on ethanolinduced liver injury Decreased activation of lipocytes to transitional cells and prevention of septa1 fibrosis PPC attenuates early manifestations of alcohol toxicity; improves mitochondrial injury Improved with SAMe Decrease in perivenular fibrosis and cirrhosis; no difference in LFT; no change in inflammatory infiltrate

Results

m

cn

W

y-Linoleic acid

Linoleic acid

Dietary saturated fats

Dietary fat composition

Saturated fatty acids

L-cysteine

Lazeroid

Segarnick, 1985

Buko, 1990

Nanji, 1995

Nanji, 1996

Nanji, 1996

Chyczewski, 1991

Sadrazadeh, 1996 Rats

Rat

Rats

Rats

Rat

Rat

Rat

Liver pathology, TNF-(Y mRNA

Liver biopsy

Enzymes of extramitochondrial fatty acid oxidation. Genes for lipid peroxidation Liver pathology, fatty acid composition, TNF-a mRNA

Liver biopsy, lipid peroxidation

LFT, liver biopsy

LFT, liver biopsy

Treatment with saturated fatty acids (palm oil or MCT) results in improved liver pathology despite continued ethanol intake Low-dose cysteine (0.012-0.024 g/100 g/day) prevents histologic change in livers of rats intoxicated with ethanol. At higher doses, cysteine worsens histologic changes of ethanol Lazeroid prevents liver necrosis and inflammation. Fatty change not affected. Reduction in lipid peroxidation Table continued on following page

Partial attenuation of alcoholic steatosis by GLA Dietaty linoleic acid improves LFT and liver biopsy changes of alcohol Diet rich in saturated fats reversed alcoholic liver injury possibly by downregulation of lipid peroxidation w oxidized fatty acyl metabolites contribute to liver injury in ALD

Ciprofloxacin

Antibiotics

Desferrioxamine (high molecular weight) Hyd roxyethyl starch desferrioxamine

Minuk, 1994

Adachi, 1995

Hossein, 1994

Liver biopsy

Rat

LFT, lipid peroxidation

Hepatic glucose metabolism

Rat

Rat

Nitric oxide modulation

Sirepar, vitohepat, carsis

Chrysanthemum balsamila extract

Skakun, 1992

Coprean, 1991

Rat

Liver pathology, lipid peroxidation, liver iron Liver biopsy

LFT, liver biopsy

Liver biopsy, liver regeneration

LFT, liver pathology

Outcome Variables

Rats

Rats

Rats

Rats

Model

Nanji, 1995

Sadrzadeh, 1997

Polymyxin-neomycin

Compound Evaluated

Imuro, 1994

Author, Year

Table 1 PRODUCTS EVALUATED IN ANIMAL MODELS OF ALCOHOLIC LIVER INJURY (Continued)

Intestinal sterilization prevents alcohol induced liver injury Ciprofloxacin reverses alcohol mediated inhibition of hepatic regeneration Polymyxin + neomycin intestinal sterilization prevents alcohol-induced liver injury No protection by iron chelation therapy Hepatic nonheme iron increased with alcohol. Therapy with HESDFO worsened alcohol-mediated hepatic injury Induction of NO prevents alcohol induced liver injury. Inhibitors of NO synthesis increase severity of alcoholic liver injury Combination of three compounds results in hepatoprotective and antioxidant activity Metabolic parameters of glucose metabolism maintained at normal levels

Results

U

m

m

Rat Rats

Picroliv

Exercise

Cytochrome P450 2E1 inhibitors (DAS, PIC)

Propolis

Rastogi, 1996

Trudell, 1995

Morimoto, 1995

Lin, 1997

LFT, liver biopsy

Liver biopsy, LFT, lipid peroxidation

Liver biopsy

LFT

LFT, liver biopsy, Kupffer cell activation

Survival, LFT

Kakkulide reduced mortality and countered hyperglycemic effects of alcohol. LFT not abnormal in animals pretreated with kakkulide Nimodipine prevents alcoholic hepatitis and inhibits endotoxin mediated Kupffer cell activation Picroliv reduced hepatic injury caused by alcohol Exercise attenuates alcohol induced fatty liver Inhibition of hepatic injury and lipid peroxidation by DAS and PIC Improvement in LFT and histology with propolis

DAS = diallyl sulfide; SAMe = S-adenosyl methionine; PIC = phenyl ethyl isothiocyanate; UDCA = ursodeoxycholic acid; LFT = liver function tests; GLA = y-linoleic acid; NO = nitric oxide; PPC = polyenyl phosphatidyl choline; TNF = tumor necrosis factor; HESDFO = hydroxyethyl starch desferrioxamine; EM = electron microscopy; MCT = medium chain triglyceride.

Rat

Rat

Rat

Nimodipine

limuro, 1996

Mouse

Kakkulide (flavinoids)

Yamazaki, 1997

Silymarin (31) versus placebo (35)

Silymarin (47) versus placebo (50)

Silymarin (17) versus placebo (19)

Silymarin (47) versus placebo (45) Silymarin (57) versus placebo (59) Silymarin (103) versus placebo (97)

Pentoxifylline (12) versus placebo (10) Pentoxifylline (48) versus placebo (48)

Thioctic acid (20) versus placebo (2) Cyanidanol (20) versus placebo (20) Cyanidanol versus placebo (35)

RCT

DB

RCT

DB

DB

RCT

DB

DB

DB

DB

Salmi. 1982

Feher. 1989

Ferenci, 1989

Trinchet, 1989

Pares, 1998

McHutchison, 1991 Akriviadis, 1997

Marshall, 1982

Colman, 1980

Henning, 1987

Treatment Options (No. Patients)

DB

Study Type

Fintelman, 1980

Author, Year

Renal function, LFT, survival LFT, survival

LFT, liver biopsy LFT, histology LFT, histology

4 wk

6 mo 12 wk 2 wk

LFT, liver biopsy, survival

3 mo

10 d

LFT, survival

2-6 y

LFT. survival

LFT, pro collagen Ill, livei biopsy

6 mo

2Y

LFT, liver biopsy

LFT

Outcome Variables

4 wk

1 mo

Duration of Therapy

Table 2. PRODUCTS EVALUATED IN HUMAN STUDIES OF ALCOHOLIC LIVER DISEASE

Faster recovery time and higher proportion of patients improved with silymarin than placebo Transaminases and histology improved with silymarin but not placebo LFT normalized, decrease in procollagen and histologic improvement Survival longer with silymarin than placebo No difference between silymarin and placebo No effect of silymarin on clinical course or survival in alcoholic cirrhosis 30-Day mortality higher in control group ( P < 0.01) Improved survival, HRS rate lower with pentoxifylline; no changes in LFT No benefit of thioctic acid over placebo No benefit of cyanidanol over placebo No benefit

Conclusions

Symptoms, LFT, liver biopsy Clinical, LFT, histology LFT

3 wk 6 mo 4 wk

6 mo 2Y

Cyanidanol (30)

Cyanidanol (25) versus placebo (25)

UDCA (11) crossover to placebo (11)

Vitamin E (33) versus placebo (34)

Vitamin E (4)

Polyunsaturated phosphatidyl choline versus placebo SAMe versus placebo SAMe versus placebo SAMe (22) versus placebo (23)

Open

DB

DB, crossover

DB

Open

DB

DB DB DB

World, 1984

Plevris, 1991

De la Maza, 1995

Rubin, 1996

Panos, 1990

Altomese, 1988 Vendemiale, 1989 Diaz-Belmont, 1996

Kovach, 1984

Plasma amino acid profile Hepatic glutathione Clinical, LFT

LFT, survival

Survival, LFT

No benefit with SAMe No benefit with SAMe Benefit of parenteral SAMe in 15 days Table continued on following page

Symptoms, LFT, histology

-

Open

Halmy, 1984

15 d

No benefit of palmitoyl catechin over placebo Symptoms, LFT, histology improved with cyanidanol therapy Improved symptoms, LFT, histology Active drug use: more alcohol consumption, no benefit with cyanidanol Significant improvement with UDCA compared to placebo No benefit in patients with decompensated alcoholic cirrhosis Improved LFT and survival with vitamin E Trend toward improvement with PPC LFT, survival histology

3 mo

DB

World. 1987

LFT, survival

LFT better with cyanidanol

LFT, histology

-

DB

LFT, histology

DB

Sanchez-Tapias, 1981 Ugarte, 1981

3 mo

Benefit with cyanidanol at 3 months on LFT No benefit with cyanidanol

LFT, histology

5 mo

Cyanidanol versus (16) placebo (15) Cyanidanol (13) versus placebo (14) Cyanidanol (12) versus placebo (13) Palmitoyl-catechin versus placebo Cyanidanol (18)

DB

Palmas, 1987

Retrospective

DB

DB

DB, multicenter

DB

DB

DB

Steinberg, 1996

Bode, 1997

Keiding, 1994

Mutimer, 1988

Bird, 1998

Majumdar, 1982

Caballeria. 1998

526, 598, 547 d 24 wk

Malotilate 1500 mg; 750 mg; placebo

Malotilate (171) versus placebo (164) Amlodipine (32) versus placebo (30) Naftidrofuryl (17) versus placebo (15)

Metadoxine (69) versus placebo (67)

4 wk

Paromomycin (25) versus placebo (25)

3m

6d

1Y

1 dose

2Y

Duration of Therapy

NAC (5) versus no treatment (6)

SAMe (62) versus placebo (61)

Treatment Options (No. Patients)

LFT.

US

LFT, ICG clearance, clinical benefit

Survival

LFT, histology, survival

Survival

LFT, endotoxemia

LFT, hospital stay

Survival

Outcome Variables

Conclusions

=

ursodeoxycholic acid;

Overall survival not different in two groups. Child’s A and B class patients better survival with SAME than placebo LFT improvement more, shorter hospital stay with NAC No effect on endotoxemia or LFT (no benefit with paromomycin) Low-dose malotilate better than high dose or placebo No difference in two treatment groups No difference between amlodipine and placebo Naftidrofuryl improves clinical, LFT and ICG clearance compared to placebo Significant improvement in fatty changes and LFT with metadoxine even in patients who continue to drink alcohol

RCT = Randomized controlled trials; DB = double blind; LFT = liver function tests; US = ultrasound; HRS = hepatorenal syndrome; UDCA NAC = N-acetyl cysteine; ICG = indocyanine green; SAMe = S-adenosyl methionine.

DB

Study Type

Mato. 1997

Author, Year

Table 2. PRODUCTS EVALUATED IN HUMAN STUDIES OF ALCOHOLIC LIVER DISEASE (Continued

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

861

HEPATOCYTOPROTECTIVE AGENTS

Silymarin

Silymarin is a mixture of flavinolignans (silibinin, silidianin, silichristin, and silybin), of which silybin is the most 37 All these flavinolignans are a complex of isometric compounds of the phenyl chromagen group and are extracted from the plant, Silybum mariunum (milk thistle), a member of the Asteraceae family. The flavinoids are at highest concentration in the fruit, seeds, and leaves of the plant.50A standard silymarin ethanol extract contains about 70% ~ i l y m a r i nSilymarin .~~ has been shown in experimental studies to protect animals against various he pa tot ox in^.^^, 34, 37, 50, 137 Studies on rat models have demonstrated an effect on free radicals, antioxidant properties, and lipid proliferation. The exact mechanisms of action of silymarin are not yet clear, but its primary mechanism of benefit is most likely to be its antioxidant properties. Various properties have been attributed to this class of flavinoids and are shown below.3, 15, 19, 28, 46, 82, 108. 110, 131, 140, 143 Postulated Mechanism of Action of Silymarin Acts as an antioxidant Inhibits lipid peroxidation of hepatocyte, microsome, and erythrocyte membranes in rats Suppresses superoxide anion and lipoxygenase Increases hepatocyte protein synthesis Decreases hepatic and mitochondria1 glutathione peroxidation Decreases activity of tumor promoters Stabilizes mast cells Protects against radiation-induced suppression of hepatic and splenic DNA and RNA synthesis Slows calcium metabolism Alters physical properties of plasma membrane (cells more resistant to osmolysis The pharmacokinetics of silybin, one of the constituents of silymarin, has been studies. It is absorbed rapidly from the gut. It reaches peak plasma concentration after 2 hours and has a half-life of 6 hours.'O It is secreted in the bile as glucuronide and sulfate conjugates. Intestinal absorption increases when it is coadministered with pho~phatidylcholine.~~ One difficulty in evaluating clinical trials using silymarin is related to their publication in non-English literature (making them difficult to evaluate and interpret). Most feature small numbers of subjects, lack of defined controls, poorly defined end points, variable degree of severity of liver disease, unknown quantity of alcohol consumed, and inclusion of patients with nonalcoholic liver disease. Another confounding factor has been the unknown proportion of patients included in the trials who become abstinent. There have been at least six published trials of silymarin in doses ranging from 80 to 420 mg/day for periods 122,134 A total of 302 patients have been treated of 4 weeks to 6 years.33,34,36,106, with silymarin and 305 patients with placebo in six studies evaluated by the authors. Normalization of liver function tests and improvement in liver histology and possibly survival were observed in a significantly higher proportion of patients treated with silymarin than placebo. None of the authors reported any adverse effects related to ~ilymarin?~, 34, 36, Io6, lZ2,134 These results appear impressive but must be placed in proper perspective.

862

MULLEN & DASARATHY

Some of the limitations of herbal products have been lack of stringent quality control (e.g., bioavailability) measures because they are not under the purview of the Food and Drug Administration and lack of randomized controlled trials. It is possible that silymarin may be an effective hepatoprotective agent. Beneficial effects on advanced liver disease and a prophylactic effect for acute hepatic lesions have also been attributed to silymarin. Well-performed, statistically validated trials are required, however, with reproducible results, before it can be considered an effective therapy for ALD. It has potential beneficial effects in patients with ALD and HCV infection.37Silymarin may prevent progression to cirrhosis because of its inhibitory effects on lipid peroxidation. It has been claimed to have anticarcinogenic effects. It also protects the liver cells from toxic substances and potentially diminishes hepatocellular necrosis and hepatic failure. Inhibition of hepatocellular necrosis also reduces the degree of collagen deposition in the liver. The possible benefit observed in patients with ALD could be related to cessation of alcohol abuse while patients are enrolled in a clinical trial. It is also possible that, in routine clinical practice, when stringent trial conditions no longer exist, patients may enhance their alcohol consumption under the misconception that their livers are ~rotected.'~' A situation could arise when a patient considers a combination of alcohol abuse and silymarin to be safe for the liver. In summary, on the basis of experimental studies in animal models, and human studies in alcoholic and other hepatic diseases, silymarin seems to be a safe, well-tolerated, and possibly effective therapy for ALD. Stringent quality assurance of the product available and well-designed randomized controlled trials are needed before firm recommendations can be made. Pentoxyfylline

Pentoxyfylline is a methylxanthine derivative with multiple effects on hemorheologic characteristics?2 It reduces blood viscosity, improves erythrocyte flexibility, and improves tissue oxygenation. It increases erythrocyte flexibility and microcirculation and potentiates the effects of endogenous prostacyclin on platelets and arterial walls. In addition, it has been shown to suppress polymorphonuclear leukocyte production of superoxide anion and lactoferrin release. A membrane-stabilizing effect also has been proposed for pentoxyfylline, as have anti-inflammatory and prostaglandin synthesis-stimulating proper tie^.^^ These hemorrheologic and prostacyclin-modifying properties may benefit hepatic microcirculation. Additional inhibitory effects on tumor necrosis factor (TNF)-a and interleukins may explain the potential benefit of pentoxyfilline in patients with alcoholic hepatitis. An initial pilot study in patients with severe alcoholic hepatitis was followed by a double-blind study in a total of 96 patients?, 78 Pentoxyfylline, 40 mg three times daily was compared with placebo over a 4-week period. Death related to hepatorenal syndrome (HRS) was reported in 18 (37.5%) of the placebo and 5 (10.4"/0)of the pentoxyfylline group.4 No improvement was noted in four of five of the parameters of the Child's score. Overall, mortality in the two groups was similar. There were 20 (41.7%) deaths in the pentoxyfylline and 11 (22.9%) deaths in the placebo group. It was concluded that short-term survival was better with pentoxyfylline than placebo and there was a significant decrease in risk for development of HRS. Unfortunately, these data have been published only in abstract form, with no details regarding the quantity of alcohol consumed or long-term effects on survival. It, however, may be concluded that this is a

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

863

promising drug and could be used in the setting of a clinical trial in patients with alcoholic hepatitis. A case report of pentoxyfilline-related fatal acute liver injury indicates the need for caution in the use of this drug.121 In conclusion, in the limited setting of advanced ALD, pentoxyfilline may be beneficial in a subgroup of patients who need to be defined clearly. Thioctic Acid

This naturally-occurring compound is a cofactor in the two key enzymes of the citric acid cycle-pyruvate dehydrogenase complex and the alpha-ketoglutarate dehydrogenase complex.86It has been shown to stimulate prostaglandin synthesis via its effect of prostaglandin cyclooxygenase. The beneficial effects of thioctic acid in ALD may be related to its antioxidant and free-radical scavenging properties. In experimental studies, 10 to 500 pg/mL of thioctic acid reduced the cytotoxicity of postethanol serum toward mouse cells and human lymphoc y t e ~ .A '~~ double-blind, randomized controlled trial was conducted in 40 patients with precirrhotic ALD treated over 6 months with thioctic acid at a dose of 300 mg/day in three divided doses or placebo. No benefit was observed with thioctic acid therapy.74Significant improvement occurred in liver function test and liver histology in patients who abstained from alcohol, irrespective of their therapy with thioctic acid. No further studies have been published. Over a decade has passed and no further interest seems to be focused on thioctic acid, a relatively safe and potentially beneficial agent. It may be worth reviving interest in the therapeutic potential of this compound as a part of a multipronged therapy for alcoholic hepatitis. In summary, thioctic acid is a potentially effective nontoxic therapy for ALD and further studies are warranted to establish or dismiss its efficacy. Cyanidanol-3 (Catechin)

Cyanidanol is a hepatoprotective agent that has been evaluated extensi~ely.~~ This naturally occurring flavanoid with antioxidant properties has lysosomal membrane-stabilizing and free radical-scavenging properties. It also has inhibitory effects on collagen synthesis in some animal In studies on rats with alcohol-related liver injury, cyanidanol normalized the nicotinamide-adenine dinucleotidide (reduced form)/nicotinamide-adenine dinucleotidide ratio and stabilized lysosomal membrane^.'^' Studies on humans, however, demonstrated no benefit with 2 weeks or 3 months of therapy in doses of 1 to 2 g/ day.48,lz3 Despite extensive evaluation in animal models, and human studies, there seems to be little evidence of measurable benefit with these corn pound^.^^^ 47, 61,Io3, 138, 14', 149 The major problems encountered with cyanidanol are the doserelated increase in collagen content of the liver (in contrast to other studies) and adverse effects of allergic hyperthermia and autoimmune hemolytic anemia.M These may be more common if higher doses are used and, as a result, there was interest in the palmitoyl derivative of cyanidanol. It was believed that a more favorable pharmacokinetic profile would be achieved with palmitoyl derivative ( + ) cyanidanol-3. In the rat model, this derivative was reported to be more effective that the parent compound at half the dose.116In a single study published later using palmitoyl catechin, no beneficial effect was observed.1so Based on initial animal and few uncontrolled human studies, cyanidanol seemed to hold promise in therapy for ALD but prospective randomized trials

864

MULLEN & DASARATHY

failed to hold up this promise. Cyanidanol seems to be a drug of the past and may perhaps not have any further role in therapy for ALD. Bile Acids

Ursodeoxycholic acid is a tertiary bile acid that has been used in cholestatic disorders."' It has various mechanisms of action, including an alteration in bile acid pool, reducing toxicity attributable to cholestasis. It also has immunomodulatory actions. It has been shown to be beneficial in patients with primary biliary cirrhosis, chronic hepatitis, and cholestasis of pregnancyz1It was suggested that its membrane-stabilizing action would be beneficial in alcoholic hepatitis and cirrhosis. In an experimental study on cell lines with ethanol-mediated injury, tauroursodeoxycholic acid was shown to exert a protective effe~t.9~ To date, however, only one short-term crossover trial with 11 patients with alcoholic cirrhosis has been published. Significant benefit was demonstrated in liver function tests in these patient^.'"^ Ursodeoxycholic acid is a safe therapy and long-term, large-scale studies are needed before it can be placed in the category of definitely beneficial drugs in ALD. Licorice Derivatives

Glycyrrhiza glabara, a licorice derivative, has been used extensively with beneficial effects in Japan and India for patients with chronic hepatitis and subacute hepatic failure.' It is suggested to have a hepatocytoprotective action and help control ongoing active hepatic necrosis from a number of causes. It has been suggested that this compound may be beneficial in ALD, although no studies have yet been published. Alpha-tocopherol (Vitamin E)

In animal studies, alpha-tocopherol was shown to have free radical-scavenging properties and an inhibitory effect on hepatic collagen gene e x p r e ~ s i o nAn .~~ inhibitory effect on lipid peroxidation was also suggested. Reduced hepatic alpha-tocopherol content was reported in rats fed alcohol and in the blood of alcoholics.'" 144 Hepatic lipid peroxidation was significantly higher after chronic ethanol feeding in rats fed a low vitamin E diet. It was, however, observed by other workers that high-dose alpha-tocopherol inhibited lipid peroxidation but did not confer protection against alcohol-mediated liver injury.120 Long-term administration of vitamin E (500 mg/day) to humans in a randomized, controlled trial did not show clinical or biochemical parameters of improvement in liver cell function compared with It was also documented that levels of alpha-tocopherol that were low in patients with severe liver disease showed an increase with supplementation. In a recent uncontrolled study, four patients with histologically documented moderate-to-severe alcoholic hepatitis were administered an enteral water-soluble preparation of alphatocopherol-D. alpha-tocopherol polyethylene glycol-1000, 25 U / d a ~ . l 'All ~ four patients were treated for up to 6 months. One died because of multisystem failure in 162 days. Two patients were followed for at least 6 months and one was lost to follow-up in 24 months. All patients had a Maddrey discriminant score of at least 17.2. The predicted mortality of these patients is at least 50% in

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

865

the short-term course. It was concluded from this single pilot study that alphatocopherol seems to improve liver function and survival without adverse effects. Effectiveness of vitamin E supplementation in the therapy and prevention of alcoholic liver injury is still being evaluated. Long-term vitamin E has been suggested to be necessary before a beneficial effect as an antioxidant can be observed. Tocotrienols, a group related to the tocopherols, has been shown to be 146 These need extensive more potent as antioxidants than the evaluation for their acceptability, efficacy, and safety. It appears that alpha-tocopherol is a promising, safe agent either alone or as adjuvant therapy in patients with ALD. Polyunsaturated Lecithin

Evidence in nonhuman primates and rodents demonstrated multiple actions of polyunsaturated lecithin (containing polyenyl phosphatidyl choline; PPC) obtained from soybean extract. The phospholipids from PPC are highly bioavailable and are readily integrated into hepatocyte rnernbrane~.~~ Choline itself, however, was shown to worsen the hepatoinjurious effects of Mechanisms of action of polyunsaturated lecithin (suggested/documented) Antioxidant activity-inhibits lipid peroxidation Decreased rate of transformation of lipocytes to fibrogenic cells Precursor to membrane-stabilizing prostaglandins-hepatocytoprotective Restores membrane activity of phosphatidyl ethanolamine N methyl transferase (PEMT) Attenuates alcohol-related decrease in methionine adenosyl transferase Inhibits acetaldehyde-induced collagen accumulation in lipocyte cultures Complex enzyme defects in ethanol abuse have been demonstrated that can be corrected by PPC. Alcohol abuse has been shown to result in decreased activity of methionine adenosyl transferase (S-adenosyl methionine synthetase and PEMT.@,68 PEMT is responsible for using S-adenosyl methionine (SAM) in the methylation of phosphatidyl ethanolamine to phosphatidyl choline. A decrease in PEMT may also be responsible for the associated decrease in phospholipids, exacerbate phospholipid depletion-related membrane abnormalities, promote hepatocellular injury, and trigger fibrosis. PPC restores the enzyme activity of PEMT in vivo. Alcohol feeding in baboons has been shown to decrease MAT, an effect attenuated by PPC.66MAT is the key enzyme in the synthesis of SAM. SAM is a methyl donor responsible for essential cellular methylation reactions. Phospholipid supplementation therefore may be hepatocytoprotective by circumventing enzyme defects in membrane function maintenance.hh,7'1 PPC treatment was shown to be effective in both prevention and attenuation of pre-existing hepatic fibrosis and cirrhosis. In studies conducted on baboons fed alcohol, oral PPC prevented septa1 fibrosis, and discontinuation of PPC resulted in accelerated ~ i r r h o s i s PPC . ~ ~ also reversed fatty liver and hyperlipidemia in rats fed Furthermore, in patients with chronic hepatitis, PPC has been shown to be beneficial in a double-blind A single human clinical trial using PPC for 2 years in 104 patients with alcoholic hepatitis demonstrated a trend to improved survival, especially in patients of Child's class B.lD4Further studies in patients with ALD are in progress. PPC seems to hold considerable promise for therapy for ALD based on animal and experimental studies and limited human studies published to date.

866

MULLEN & DASARATHY

S-Adenosyl Methionine

The rationale of SAM treatment is based on sound theoretical grounds and animal 35, 65,76, Io2 SAM contains a sulfonium ion, which makes it a highenergy compound that can transfer its methyl group to a variety of compounds. Defective methylation can affect cellular growth, differentiation, and function. The exact mechanism of the beneficial effects of SAM is unclear. It is a source of cysteine for glutathione production. Glutathione is the major methyl donor for transmethylation for nucleic acid and protein synthesis, membrane phospholipid methylation, and formation of polyamines necessary for cellular regeneration. Glutathione deficiency occurs in the cytoplasm and mitochondria of hepatocytes in alcohol-exposed animals and humans.35,72 SAM has been demonstrated to prevent changes in mitochondria1 fluidity in experimental models of alcoholic liver injury and therefore may be beneficial. It also has been shown that TNF-a and endotoxemia may be reasons for alcohol-mediated cellular damage. Recent data suggest that SAM downregulates TNF-a mRNA and protein synthesis by mouse macrophages stimulated by lipopolysaccharide/endotoxin.22,40, 65, 147 These may be an additional mechanism for hepatoprotection by SAM. Furthermore, SAM deficiency occurs after chronic ethanol consumption. This has been attributed to a decrease in ASH/MAT, the enzyme responsible for SAM An alteration in betaine metabolism and a beneficial effect of betaine in animal models has been suggested? The role of betaine in human treatment has been questioned, however, because of the absence of betaine in the pathway of SAM synthesis." Orally administered SAM is a precursor for intracellular SAM. Compared with methionine (the precursor for SAM), SAM administration has the advantage of bypassing the enzymatic defect related to MAT deficiency. SAM supplementation corrected the deficiency in SAM and ameliorated alcohol-induced 142 liver injury and possibly fibrosis in Earlier studies had shown few or no beneficial effects of SAM therapy in ALD.h,2y, 14* In contrast, in a recently published randomized double-blind, placebo-controlled trial on 123 patients with alcoholic cirrhosis, SAM was administered in a dose of 1 to 2 g / d for 2 years.76Sixty-one patients received placebo and 62 were treated with SAM. Alcohol abstinence was similar in the two groups (52% in placebo and 50% in SAM group). Overall survival was higher with SAM (90%) compared with placebo (72%) at the end of 2 years. A Kaplan Meier survival analysis, however, did not demonstrate significant difference between the two groups. A post hoc subset analysis demonstrated that exclusion of patients in Child's C class resulted in a significant difference, with improved survival in the SAM group.3o SAM has been shown to be a safe and welltolerated compound. Further studies are needed to explore this therapy in patients with ALD. SAM seems to be a promising drug for therapy for ALD and has the advantages of promising experimental and human studies. N-Acetyl Cysteine

In a case control type of analysis, alcoholic patients who had used acetaminophen were treated with N-acetyl cysteine (NAC).130 All patients had serum acetaminophen levels less than 5 pg/mL and ethanol levels greater than 100 ng/ dL at admission. None of the patients presumably had consumed an overdose of acetaminophen. Five patients administered a single dose of NAC were compared

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

867

with six historical patients who received no therapy. Mean duration of hospital stay was shorter in the NAC-treated patients (2.0 ? 2.6 days) compared with untreated patients (6.0 2 1.4 days). It was suggested that NAC may benefit patients with acute alcoholic hepatitis without acetaminophen toxicity. The rationale for this form of therapy is that alcohol abusers are likely to consume acetaminophen, and they may be more susceptible to acetaminophen hepatotoxicity because of decreased glutathione stores. Countering this adverse effect of acetaminophen therefore may help decrease the hepatic injury. It is an interesting concept but with a single, retrospective case control study being the only evidence in its favor, it is unlikely to be considered a standard therapy. NAC also has been suggested to at least partially prevent the hypoxia-induced MAT inactivation. This would result in an increase in hepatic SAM.72Prospective randomized controlled trials are needed to evaluate this agent. It does appear rational to treat patients for at least one of the potentially injurious agents in those already having ethanol-mediated hepatic injury. Dietary Saturated Fat

Dietary fat may be a determinant of the severity of hepatic injury in ALD. Saturated fatty acids have been considered to be beneficial in ALD. ALD is associated with hepatic fatty acid acc~mulation.~~, 142 It has been observed in the rat intragastric alcohol feeding model that, despite high blood alcohol levels maintained for months, liver pathology does not develop if the diet is low in linoleic and polyunsaturated fatty Alterations in fatty acid binding protein and extramitochondrial fatty acid oxidation pathways were demonstrated in experimental studies on rats fed Increased production of oxidized fatty acyl metabolites may contribute to the liver injury in ALD. A diet containing saturated fatty acids would be expected to reduce the concentration of polyunsaturated fatty acids (PUFA) in the liver and diminish the substrate for lipid peroxidation. Polyunsaturated fats, because of their multiple double bonds, are potentially more susceptible to free radical peroxidation than saturated or monounsaturated fats. Saturated dietary fats fed in association with ethanol diminish lipid peroxidation and the activity of cytochrome P4502E1 (CYP2E1), which contributes to the lipid peroxidation and synthesis of vasoactive and proinflammatory eicosanoids by cyclo-oxygenase (Cox).96Both lipid peroxides and endotoxin induce Cox-2, so Cox-2 may be the final step for the mediation of alcohol-induced liver injury?' Saturated fatty acids have been shown to improve hepatic injury in rats both while continuing and after discontinuation of ethanol intake.92These observations have been contradicted by other groups of investigators, who have shown a beneficial effect of y-linoleic acid in ALD.lZS Treatment with palm oil or medium-chain triglycerides as the source of lipids in human patients may ameliorate hepatic injury mediated by alcohol. The amount and type of fatty acid in the diet may affect eicosanoid synthesis. Dietary fats therefore may have pharmacologic effects in addition to being nutrients. Fish oil (rich in 0 - 3 unsaturated fatty acids) has been compared with palm oil (rich in saturated fats) in a rat model. It was shown that fish oil did not result in pathologic changes in the liver in the absence of alcohol but did so in the presence of alcohol. Palm oil, on the other hand, reversed the ethanolinduced hepatic pathology. These effects have been suggested to be secondary to the differences in lipid peroxidation with these These authors also demonstrated a beneficial effect of medium-chain triglycerides with vitamin E in reducing the severity of alcoholic liver injury in a rat The documented

868

MULLEN &I DASARATHY

cardiovascular risks of saturated and the benefits of polyunsaturated fats in humans need to be weighed against the putative risks demonstrated in rats with PUFA. Studies are needed to test this hypothesis in human alcoholic liver injury. Caution should be exercised before recommendations are made in humans. Studies conducted by one major group, in a rat model and without further validation, make this an attractive option, but it needs extensive validation by other groups and in humans before firm recommendations can be made. Cimetidine

Cimetidine has been shown to diminish the severity of alcoholic liver injury in a rat model. This benefit has been attributed to a decreased ratio of thromboxane 82 to prostacyclin, which may improve hepatic microcirculation.97 Given the effect of cimetidine on the cytochrome P450 system, this compound may be well worth further evaluation as therapy for alcoholic liver injury. Amino Acids

Glycine has been shown in studies to protect renal and liver cells against 155 Inactivation of Kupffer cells by glycine has hypoxic and reperfusion injury.100, been the most frequently proposed explanation for its beneficial effects. In a rat model, glycine was found to improve liver function tests and liver histology, possibly by enhancing first-pass metabolism of alcohol in the stomach.53This, in turn, could be related to cytoprotective effects on gastric cells that contain alcohol dehydrogenase activity. L-cysteine has been evaluated in a rat model and found to be beneficial at a low dose in preventing alcoholic liver injury. L-cysteine at a higher dose, on the other hand, worsened the hepatic pathology related to ethanol intake.I5* These are interesting observations, but further studies are needed before these can be considered as a treatment options. Lazeroids

Lazeroids are a newly described class of compounds with antioxidant and membrane-stabilizing properties. In experimental studies of rats fed ethanol to induce ALD, treatment with lazeroids was beneficial. Necrosis and inflammation were inhibited, but no effect on hepatic fat was ob~erved."~ The improvement in pathologic changes and reduction in lipid perioxidation were considered the effects of the antioxidant properties of lazeroids. No human studies or complete papers have been published about this interesting group of compounds. Antibiotic Agents

Endotoxemia-mediated Kupffer cell activation (see Fig. 1) has been considered to be one of the mechanisms of ALD.39 Hypermetabolism and hypoxia induced by endotoxin were also considered mechanisms of alcohol-mediated liver injury. Reduction of endotoxemia by intestinal sterilization in the rat model of ethanol-induced liver injury showed beneficial effects.2 Gut sterilization

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

869

achieved using nonabsorbable antibiotic treatment such as polymyxin-neomycin resulted in significantly lower levels of hepatic transaminases, histologic improvement in steatosis, and necroinflammation compared with placebo.52It was concluded that alcohol-induced liver injury in the rat model could be prevented by intestinal sterilization. Another antibiotic, ciprofloxacin, has been studied in rats fed Inhibition of hepatic regeneration mediated by ethanol was reversed by ciprofloxacin. The mechanism of action of ciprofloxacin was considered to be related to its y-aminobutyric acid (GABA,) receptor antagonist propertys1 The intestinal sterilization and antiendotoxemia effects are other possible ways by which ciprofloxacin could have been benefi~ial,"~ but they were not evaluated in the study. In a human study of patients with alcoholic liver injury (cirrhosis, 27 patients; precirrhosis, 23 patients) subjected to a RCT with paromomycin, no significant effect on serum endotoxin concentrations or liver function tests was observed over 4 weeks.I4 It appears that antibiotics could be beneficial in patients with ALD. Further studies are needed before definite conclusions can be drawn. Macromolecular Deferoxamine

Accumulation of hepatic iron has been one of the postulated mechanisms of ethanol-mediated hepatic injury, lipid peroxidation, and pathologic Initial evaluation of high-molecular-weight desferrioxamine in rats showed no beneficial effects of iron chelation therapy.119In a subsequent study of rats fed ethanol and treated with hydroxyethyl starch deferoxamine, no benefit was demonstrated.118Plasma alanine aminotransferase was significantly higher in the rats treated with deferoxamine than those undergoing no treatment. It was suggested that high-molecular-weight deferoxamine was not effective in these models of ALD. It was possible that this form of therapy actually worsened alcohol-mediated liver injury. The authors suggested that it cannot be concluded from their limited studies that iron chelation therapy was ineffective.11x In the absence of positive benefits reported from animal studies, iron chelation as a primary therapy for ALD is unlikely to gain popularity among investigators. Nitric Oxide Modification

Perivenular hypoxia has been suggested to be a mechanism for alcoholic liver injury. Alcohol intake results in increased hepatic oxygen consumption.154 Ethanol consumption also results in an increase in hepatic blood flow, which has been considered to be a compensatory mechanism for the increased oxygen consumption?" Nitric oxide (NO), a potent vasodilator, may be the modulator of the hepatic vascular bed. Altered vascular sensitivity to NO or decreased NO production are believed to contribute to the pathophysiology of alcoholic liver injury.145 Both Kupffer cells and hepatocytes synthesize NO in the liver. Adaptive NO synthesis in the liver has also been suggested to be beneficial to hepatocytes in the presence of endotoxemia.lObIncreased NO synthesis during endotoxemia prevents liver injury by reducing oxygen radical-mediated tissue damage.47aNO production by nonparenchymal cells may play a significant role in maintaining hepatic microcirculation in the presence of low levels of endotoxins.lOOa As already stated, endotoxemia has been one of the mechanisms implicated in the

870

MULLEN & DASARATHY

pathogenesis of liver injury in alcoholic liver disease. Less-than-appropriate NO response in alcohol-fed rats may enhance the severity of liver damage.9O Furthermore, inhibition of NO formation by the liver in vivo has been associated with an increased production of superoxide from Kupffer cells.IaaSuperoxide may result in proinflammatory and injurious effects to the h e p a t o c y t e ~ .It~ ~ therefore appears that NO production may be a protective mechanism in alcoholexposed livers. Inhibition of this response may enhance or be responsible for the alcohol-mediated injury. In a rat model, NO inhibition was shown to result in enhanced liver injury when rats were exposed to lipopolysaccharide or alcohol. Stimulating NO production with L-arginine could prevent injury.lob Decreased production of NO has been suggested to be related to the downregulation of NO synthase by products of lipid peroxidation or TNF-related 72, 153a Decreased NO, therefore, may result in enhanced degradation of adverse vascular supply to the hepatocytes and thereby culminate in injury. It also has been suggested that NO, itself, may act as an antioxidant through its interaction with superoxide and other toxic free r a d i ~ a l s . 5Other ~ ~ cytoprotective effects of NO production by hepatic sinusoidal cells may be related to its inhibition of platelet activation.112b Inhibition of NO formation favors platelet adhesion and aggregation and release of vasoconstrictor mediators that aggravate the hepatic hypoxia. Decreased NO has also been associated with increased leukocyte adhesion to postcapillary venules, promoting leukocyte recruitment, a feature of alcoholic hepatitis.I6,61a An alternative possibility is that NO, itself, is injurious to hepatocytes. The NO produced in the centrilobular region may de-energize mitochondria and lead to hepatocyte damage.113a Alternatively, NO could combine with other free radicals such as superoxide and produce very cytotoxic compounds, such as peroxynitrite.'IzaThe mechanisms that govern the toxic or protective potential of NO are unclear. It is possible that other antioxidant systems, such as reduced glutathione or oxidized glutathione (GSH) may determine whether NO is protective or A recent study on MAT 1 RNA and protein synthesis showed that the inactivation of the liver-specific tetrameric MAT in the first 6 hours of hypoxia was most likely mediated by nitric oxide, the production of which increased under hypoxic conditions.*This brings back MAT into the picture of the pathogenesis of ALD and suggests a role for its modification as treatment. Blocking NO synthesis by N-nitro-L-arginine methyl ester (L NAME) inhibited the hypoxic inactivation of MAT.*, 72 L NAME therefore seemed to protect against hypoxia-induced MAT inactivation. Despite the potential benefit of blocking NO synthesis, the effects of the potentially preserved MAT activity-i.e., GSH levels-were not increased (GSH levels are determined by SAM synthesis mediated by MAT).72It therefore is still unclear whether NO is beneficial or harmful in hypoxic and alcoholic liver injury. From published data, NO appears to be a double-edged sword. Much needs to be done before a clear understanding of the role of NO and the clinical applications of its modifications in the therapy of ALD can be reached. Malotilate

Malotilate (diisopropyl 1,3 dithiol - 2 ylidene malonate) has been shown to be beneficial in experimental liver injury in animals. It has been suggested to decrease fibrogenesis and accumulation of fat. It also promotes protein synthesis

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

871

and hepatocyte regeneration.'z8 Its mechanism of action is obscure. Studies on humans have produced inconsistent results: In a large multicenter study of 335 patients with alcoholic hepatitis, treated up to 24 weeks, survival was not affected.88In a recent study with two dosage schedules, 750 mg/d of malotilate was found to improve survival compared with 1500 mg/d of malotilate or placeb0.5~The latter two groups were not significantly different. Malotilate has few beneficial effects in patients with ALD. Data published to date do not strongly support malotilate as a promising agent in ALD. Based on the promising results from the recent study, however, it may be worth reviewing under more stringent trial conditions. Calcium Channel Blockers

Activation of Kupffer cells by intracellular calcium via L-type calcium channels may be involved in alcohol-induced liver injury." Chronic ethanol administration upregulates calcium channels in Kupffer cells4,4y Calcium channel blockers prevent Kupffer cell activation and have been shown to be beneficial in reducing hypoxic liver injury and increase graft survival following liver tran~plantation.'~~, 132 Nimodipine, a dihydropyridine type of calcium channel blocker, has been shown to prevent alcoholic hepatitis in rats.s4Nimodipine has also been shown to block the swift increase in alcohol metabolism and minimize elevation in intracellular calcium mediated by endotoxins in Kupffer cells.1s4 Hepatic microcirculation potentially also could be improved by calcium channel Hepatic Ito cells contain calcium channels, and could regulate hepatic microcirculation, thereby diminishing hepatic oxygen delivery.'"' Nimodipine could potentially alter Ito cell contraction and thereby prevent hypoxia or reoxygenation hepatocyte injury in pericentral zones of the liver. Because L-type calcium channels do not exist in hepatocytes, nimodipine perhaps does not have direct effects on hepatocytes.112Strong experimental evidence therefore favors manipulation of Kupffer cell function pharmacologically with nimodipine. Nisoldipine, a related dihydropyridine-type calcium channel blocker, has been shown to decrease the release of TNF-a and interleukin-6 after rat liver transplantati~n.'~~ It is possible that calcium channel blockers could diminish or block release of cytokines and ameliorate the ethanol-mediated hepatocyte injury. Endotoxin and lipopolysaccharide-induced Kupffer cell activation has also been shown to be attenuated by calcium channel Biochemical and histologic parameters of improvement have been documented with calcium channel blockers in experimental toxin-mediated liver A combination of a calcium channel blocker with SAM has been shown to be beneficial in a rat model of ALD.25 Nimodipine, a calcium channel blocker, has been shown to decrease alcohol withdrawal symptoms in humanss All this experimental and clinical evidence seems to suggest that there may be a role for treating patients with a dihydropyridine-type calcium channel blocker. In a recent study using amlodipine, a dihydropyridine-type calcium channel blocker was used in a 4-week trial in 62 patients with acute alcoholic hepatitis at a dose of 5 to 10 mg/d. There was no benefit in short-term survival compared with placebo." Amlodipine was safe and well tolerated but without beneficial effects. Flavinoids

Other flavinoids that have been used with potentially beneficial effects are chrysanthemum extract, kakkulide, and s i s e ~ a n .lz9, ~ ~153, Propolis, a mixture of

872

MULLEN & DASARATHY

gums, resins, and balms from the buds and bark of plants and trees (especially coniferous trees) collected by honeybees, had been reported to be beneficial in a rat model of ALD.'I Cabbage extract has also been shown to be beneficial in a rat model of ALD.'3y Picroliv, an herbal product, has been evaluated for its antiviral and hepatocytoprotective properties and found beneficial in animal studies.Il3 With few exceptions, these publications have been in non-English or non-peer-reviewed journals and reported studies done in animal models. Other groups have not reproduced the results. Furthermore, these are herbal products with uncertain quality control of the products. With these limitations, it is uncertain whether these products will ever reach the stage of well-performed clinical trials that are necessary before accepting them as standard therapy. Cytochrome P450 2E1 Inhibitors

Cytochrome P450 2E1 (CYP2E1) is the enzyme implicated in the metabolism of ethanol and generation of acetaldehyde and free radicals.26CYP2E1 is induced by ethanol and can metabolize a large number of xenobiotics, many of which are activated to cytotoxic This enzyme can initiate membrane lipid peroxidation in the presence of nonheme iron. Diallyl sulfide (DAS) and phenethyl isothiocyanate have been used to inhibit CYP2E1 in the rat model of alcohol-induced liver injury. DAS inhibits ethanol-dependent perivenous hepatic damage as assessed by fibrosis, inflammation, and fatty changesR7They also caused a decrease in the rate of microsomal lipid peroxidation and prevented the increase in plasma lipid hydroperoxides caused by ethanol treatment.5RThis suppression of lipid peroxides results in decreased inflammation and fibrosis. It appears that inhibition of CYP2E1 reduces the liver pathology induced by alcohol in rats. CYP2E1 levels have been shown to be sensitive to dietary modification.", y4 CYP2E1 levels have been shown to be decreased in the livers of rats fed saturated fats, in contrast to rats fed unsaturated fats, in which no such decrease was Further studies are needed to confirm these observations and develop safe and tolerated compounds for human use. Naftidrofuryl

Naftidrofuryl is the acid oxidate of 2 diethylamino ethyl tetrahydro a-lnaphthylmethyl 2 furan propionate ester (praxilene). It has been shown in experimental models to stimulate glucose, oxygen, and energy m e t a b ~ l i s m It .~~ improves intracellular energy metabolism and reverses anaerobic metabolism of pyruvate in hypoxic cells. A double-blind randomized trial was conducted on 32 patients with 40-mg naftidrofuryl intramuscularly three times daily for 6 days or placebo. Improvement in indocyanine green clearance occurred in 11 of 17 patients treated with naftidrofuryl and 4 of 15 in the placebo group. Normalization of serum gamma glutamyltranspeptidase was observed more often in the naftidrofuryl than the placebo group. It was concluded that naftidrofuryl may improve hepatic membrane transport and oxygen and energy use by hepatocytes impaired by Despite the urging of the authors and the favorable results obtained in a single randomized, controlled trial, no further studies have been published.

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

873

Naftidrofuryl seems to be a safe, well tolerated, and promising drug in the treatment of alcoholic liver injury. Exercise

Ethanol-induced fatty liver in rats was attenuated by repeated running exercise.135It is possible that a healthy behavior pattern would reinforce the beneficial effect of abstinence on ALD. Human studies should be possible and, if shown to be beneficial, the practice must be promoted given the multiple beneficial effects of exercise. Misoprostol

In a rat model of alcoholic liver injury, a synthetic derivative of prostaglandin El, misoprostol, at a mean daily dose of 80 mg/kg/d ameliorated the hepatocyte mitochondria1 dysfunction induced by ethanol exposure. This could have a potentially beneficial effect on the lipid abnormalities, hypoxia-mediated changes in lipid peroxidation, and MAT expression.31Benefits of modification of arachidonate metabolism are further supported by observations that dietary ylinoleic acid has been demonstrated to improve liver function tests and hepatic histology in rats fed ethan01.I~ Metadoxine

Metadoxine (pyridoxal L 2 pryyolidone 5 carboxylate) is a combination of pyridoxine and pyrrolidone carboxylate (PCA).lSPCA is involved in the metabolic pathway of synthesis and degradation of GSH. Experimental studies have shown that these compounds restore the hepatic levels of reduced GSH. Metadoxine also accelerates plasma clearance of ethanol and acetaldehyde and decreases the time for which the liver and other tissues are exposed to the toxic effects and metabolites of ethanol. In a randomized, controlled trial in 136 patients with alcoholic fatty liver, metadoxine in a dose of 1500 mg/d was shown to result in significant improvement in liver function tests and sonographic features of fatty liver.IMThis improvement was found even in patients who continued to drink. This appears to be a promising drug given the high recidivism rates in patients with ALD and low rates of attaining abstinence. MOLECULAR TARGETS

Reversal of hepatic fibrosis may be achieved by modifying DNA encoding procollagen to inhibit fibrogenesis. Alternatively, collagen degradation could be promoted by the use of proline analogs (inhibitors of prolyl 4 hydroxylase are also being evaluated). Cytokines such as TNF-a have been suggested to result in alcoholic hepatitis. Antibodies to TNF-a may be beneficial in ethanol-mediated hepatic injury. Quinone derivative (E3330) has been used with beneficial effects in experimental alcoholic liver injury in rats. The protective effect of E3330 has been suggested to be secondary to inhibition of thromboxane, leukotrienes, and TNF?3 Modification of the MAT1 A gene may be possible in the not distant future. The promoter for the rat MATlA has been ~haracterized.~ The

874

MULLEN & DASARATHY

effect of modifying this needs evaluation. This may need to be studied in human hepatocytes. Recombinant human growth hormone that stimulates insulin-like growth factor 1 and possesses anabolic properties has been evaluated in 20 patients (rHGH-10; placebo 10) for 6 weeks. No improvement in liver function tests occurred with this therapy.83In the absence of clinical benefits and given the expense of this mode of treatment, it is unlikely to be a widely evaluated compound for ALD. CONCLUSION

Current understanding of ALD revolves around the development of hepatocyte injury related to a variety of mechanisms, some of which include endotoxemia; hypoxia-reperfusion in the perivenous areas; acetaldehyde-mediated injury; induction of cytokines, especially TNF-a; alteration and induction of cytochrome P4502E1; and modulation of NO. Additional factors may include alterations in eicosanoid metabolism and changes in membrane lipid characteristics. One can argue that effective therapy for ALD should be directed against multiple mechanisms. Alcohol abstinence is clearly still the most important aspect of care for patients with ALD. Given the frequent failure to achieve abstinence, however, it becomes imperative to consider therapy in patients who continue to drink. In practical terms, it has been suggested that instead of a long-term treatment plan, repeated short-term treatment might result in better patient compliance and res~lts.'~' During these bursts of short-term treatments, combination therapy may be superior to single-agent treatment. Furthermore, it is clear from an objective review of published data that no single agent can truly be claimed to be completely effective. From the gamut of available treatment options, it may be worth trying a combination of silymarin (milk thistle), PPC, and SAM. Other options need to be considered, Dossiblv onlv in clinical trial situations. It seems that future trends should be toward therapy targeted toward multiple steps of the pathogenesis of ALD. . 1

J

,

References 1. Acharya SK, Dasarathy S, Tandon A, et al: A preliminary open trial on interferon stimulator (SNMC) derived from glycyrrhiza glabora in the treatment of subacute hepatic failure. Indian J Med Res 989:69-74, 1993 2. Adachi Y, Moore LE, Bradford BLJ, et al: Antibiotics prevent liver injury in rats following long-term exposure to ethanol. Gastroenterology 108:218-224, 1995 3. Agrawal R, Kauyar SK, Lundgren DW, et al: Inhibitory effect of silymarin, an antihepatotoxic flavinoid, on 12-0-tetradecanoy1phorbo1-13-acetate-inducedepidermal ornithine decarboxylase activity and mRNA in SENCAR mice. Carcinogenesis 15:1099-1103, 1994 4. Akriviadis R, Botta R, Briggs W, et al: Improved short term survival with pentoxyfylline treatment in severe acute alcoholic hepatitis. Hepatology 26:50A, 1997 5. Altamura AC, Regazzatti MG, Porta M: Nimodipine in human alcohol withdrawal syndromean open study. Eur Neuropsychopharmacol 1:37-40,1990 6. Altomere A, Vendemiale G, Marchesini G, et al: Increased bioavailability of sulphated compounds after S-adenosyl L-methionine (SAMe) administration to alcoholics. In Kuriyama K, et a1 (eds): Biomedical and Social Aspects of Alcohol and Alcoholism. Amsterdam Excerpta Medica 353-356, 1988 7. Alvarez L, Sanchez-Gongora E, Mingorance J, et al: Characterization of rat liver-

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

875

specific methionine adenosyltransferase gene promoter. J Biol Chem 272:2287522883, 1997 8. Avila MA, Carretero MV, Rodriguez EN, et al: Regulation by hypoxia of methionine adenosyltransferase activity and gene expression in rat hepatocytes. Gastroenterology 1143366371, 1998 9. Barak AJ, Beckenhauer HC, Tuma DJ: S-adenosylmethionine generation and prevention of alcoholic fatty liver by betaine. Alcohol 11:501-503, 1994 10. Barzaghi N, Crema F, Gatti G, et al: Pharmacokinetic studies in 1dB 1016, a silybinphosphatidylcholine complex in healthy human subjects. Eur J Drug Metab Pharmacokinet 15:333-338, 1990 10a. Billiar TR, Curran RD, Harbrecht BG, et a1 Modulation of nitrogen oxide synthesis in vivo: N-monomethyl 1 arginine inhibits endotoxin-induced nitrite/nitrate biosynthesis while promoting hepatic damage. J Leukoc Biol565-570, 1990 lob. Bautista AP, Spitzer JJ: Inhibition of nitric oxide formation in vivo enhances superoxide release by the perfused rat liver. Am J Physiol266G7834788, 1994 11. Bird GLA, Prach AT, McMahon AD, et al: Randomized controlled double blind trial of the calcium channel antagonist amlodipine in the treatment of acute alcoholic hepatitis. J Hepatol 283196198, 1998 12. Bird GLA, Williams R Treatment of advanced alcoholic liver disease. Alcohol Alcohol 25~197-206, 1990 13. Bjomeboe GEA, Bjomeboe A, Hagen BF, et al: Reduced hepatic alpha-tocopherol content after long term administration of ethanol to rats. Biochem Biophys Acta 918~236-247, 1987 14. Bode C, Schafer C, Fukul H, et al: Effects of treatment with paromomycin on endotoxemia in patients with alcoholic liver disease-a double blind, placebo-controlled trial. Alcoholism Clin Exp Res 21:1367-1373, 1997 15. Bosigio E, Benelli C, Piroki 0 Effect of flavinolignans of Silibum marianum on lipid peroxidation in rat liver microsomes and freshly isolated hepatocytes. Pharmacol Res 25:147-154, 1992 16. Brunt WJ, Kew MC, Scheuer PJ, et al: Studies in alcoholic liver disease in Britain. Clinical and pathological patterns related to natural history. Gut 15:52-58, 1974 17. Buko VU, Lukivskaia Ola, Zimatkin SM: The effect of a diet with different contents of linoleic acid on the development of alcoholic liver diseases [Russian]. Vopro Pitan 65-0, 1990 18. Cabellaria J, Pares A, Bru C, et al: Metadoxine accelerates fatty liver recovery in alcoholic patients: Results of a randomized double blind, placebo-controlled trial. J Hepatol 28:54-60, 1998 19. Carini R, Comoglio A, Albano E, et al: Lipid peroxidation and irreversible damage in the rat hepatocyte model: Protection by the silybin-phospholipid complex 1dB 1016. Biochem Pharmacol43:2111-2115, 1992 20. Cho SH, Choi YS Lipid peroxidation and antioxidant status affected by different vitamin E levels when feeding fish oils. Lipids 29:47-52, 1994 21. Cirello NW, Zwas FR Ursodeoxycholic acid in the treatment of chronic liver disease. Am J Gastroenterol 893447-1452, 1994 22. Cole11 A, Garcia-Ruiz C, Morales A, et al: Transport of reduced glutathione in hepatic mitochondria and mitoplasts from ethanol-treated rats: effect of membrane physical properties and S-adenosyl-L-methionine.Hepatology 26:699-708, 1997 23. Colman JC, Morgan MY, Scheuer PJ, et al: Treatment of alcohol-related liver disease with ( + ) cyanidanol-3: A randomized double-blind trial. Gut 21:965-969, 1980 24. Coprean D, Giurgea R, Rusu M, et al: Hepatoprotector effect of Chrysanthemum balsamita extract in ethanol intoxicated rats. Revue Roumaine de Physiologie 28:2729, 1991 25. Cutrin C, Menino MJ, Otero X, et al: Effect of nifedipine and S-adenosylmethionine in the liver of rats treated with CC14 and ethanol for one month. Life Sci 51:113118, 1992 26. Dai Y, Rashba-Step J, Cederbaum AI: Stable expression of cytochrome P4502E1 in Hep G2 cells: Characterization of catalytic activities and the production of reactive oxygen intermediates. Biochemistry 32:6928-6937, 1993

876

MULLEN & DASARATHY

27. de la Maza MP, Petermann M, Bunout D, et al: Effects of long-term vitamin E supplementation in alcoholic cirrhotics. J Am Coll Nutr 14192-196, 1995 28. Desplaces A, Choppin J, Vogel G, et al: The effects of silymarin on experimental phalloidine poisoning. Arzneimittelforschung 25:89-96, 1975 29. Diaz Belmont A, Dominguez Henkel R, Uribe Ancira F: Parenteral S-adenosylmethionine compared to placebos in the treatment of alcoholic liver diseases. [Spanish] An Med Interna 13:9-15, 1996 30. Duce AM, Ortiz P, Cabrera C, et al: S-adenosyl methionine synthetase and phospholipid methyltransferase are inhibited in human cirrhosis. Hepatology 8:65-68, 1988 31. Dugosz JW, Korsten MA, Lieber CS: The effect of the prostaglandin analoguemisoprostol on rat liver mitochondria after chronic alcohol feeding. Life Sci 49:969978, 1991 32. Faulstich H: New aspects of amanita poisoning. Klinische Wochenschrift 57:11431152, 1979 33. Feher J, Deak G, Muzes G, et al: Hepatoprotective activity of silymarin (Legalon) therapy in patients with chronic liver disease. Orv Hetil 1302723-2727, 1989 34. Ferenci P, Dragosics 8, Dittrich H, et al: Randomized controlled trial of silymarin treatment in patients with cirrhosis of the liver. J Hepatol 9:105-113, 1989 35. Fernandez C, Checa JC, Garcia-Ruiz C, et al: Improved uptake of glutathione by hepatic mitochondria from chronic ethanol fed rats. Kinetic studies in vitro and in vivo and susceptibility to oxidant stress. J Clin Invest 87397405, 1991 36. Fintelmann V, Albert A: Nachweis der therapeutischen Wirksamkeit von Legalon bei toxischen Lebererkrankungen im Doppelblindversuch. Therapiewoche 30:55895594, 1980 37. Flora K, Hahn M, Rosen H, et al: Milk thistle (Silybum marianum) for the therapy of liver disease. Am J Gastroenterol93:139-143, 1998 38. French SW Rationale for therapy for alcoholic liver disease. Gastroenterology 109:617-620, 1995 39. Fukui H, Brauner B, Bode JC: Plasma endotoxin concentrations in patients with alcoholic and non-alcoholic liver disease: Re-evaluation with an improved chromogenic assay. Hepatology 12:162-169, 1991 40. Gasso M, Rubio M, Varela G, et al: Effects of S-adenosylmethionine on lipid peroxidation and liver fibrogenesis in carbon tetrachloride-induced cirrhosis. J Hepatol 25~200-205, 1996 41. Gatti G, Perucca E: Plasma concentrations of free and conjugated silybin after oral intake of a silybin-phosphatidylcholinecomplex (silipide) in healthy volunteers. Int J Clin Pharmacol Ther 32:614-617, 1994 42. Gilman AC, Rall TW, Nies AS, et a1 (eds): Goodman and Gilman’s The Pharmacologic Basis of Therapeutics, ed 8. New York, Peragamon Press, 1990 43. Gluud C, Henrikson JH, Nielson G: Prognostic indicators in alcoholic cirrhotic men. Hepatology 8:222-227, 1988 44. Goto M, Lemasters JJ, Thurman RG: Activation of voltage dependent calcium channels in Kupffer cells by chronic treatment with alcohol in the rat. J Pharmacol Exp Ther 2671264-1268, 1993 45. Grant BF, Dupour MC, Hanford TC: Epidemiology of alcoholic liver disease. Semin Liver Dis 812-25, 1988 46. Hakova H, Misurova E: The effect of silymarin and gamma radiation on nucleic acids in rat organs. J Pharm Pharmacol45:910-912, 1993 47. Halmy L, David K, Nagy I, et al: Clinical, enzymological and histological changes in chronic diffuse liver diseases following ( + )-cyanidan013 (Catergen) treatment. Acta Physiol Hung 64:461470, 1984 47a. Harbrecht BG, Billar TR, Stadler NJ, et al: Inhibition of nitric oxide synthesis during endotoxemia promotes intrahepatic thrombosis and an oxygen radical-mediated hepatic injury. J Leukoc Biol 52:390-394, 1992 48. Henning H: Influence of ( + ) cyanidanol 3 in chronic alcoholic liver injury. In Conn HO (ed): International Workshop on ( + ) cynanidanol-3 in Diseases of the Liver. Royal Society of Medicine International Congress and Symposium Series No 47. London, Royal Society of Medicine, 1987, pp 177-179

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

877

49. Hijoka T, Goto M, Lemasters JJ, et al: Effect of short-term ethanol treatment on voltage dependent calcium channels in Kupffer cells. Hepatology 18:400-405, 1993 50. Hobbs C: Milk Thistle. The Liver Herb. Capitola, CA, Botanical Press, 1992 51. Houglum K, Lee M, Buck M, et al: Long and short term a-tocopherol supplementation inhibits liver collagen a (1) gene expression. Hepatology 26:250A, 1997 52. Iimuro Y, Adachi T, Moore LE, et al: Liver injury following chronic exposure of rats to ethanol is prevented by antibiotics. Hepatology 20:316A, 1996 53. Iimuro Y, Bradford BU, Forman DT, et a1 Glycine prevents alcohol-induced liver injury by decreasing alcohol in the rat stomach. Gastroenterology 110:1536-1542, 1996 54. Iimuro Y, Ikejima K, Rose ML, et a1 Nimodipine, a dihydropyridine-type calcium channel blocker, prevents alcoholic hepatitis caused by chronic intragastric ethanol exposure in the rat. Hepatology 24:391-397, 1996 55. Ingleman-Sundberg M, Johansson J, Pentilla KE, et al: Ethanol inducible cytochrome P4502E1: Genetic polymorphism, regulation and possible role in the etiology of alcoholic induced liver disease. Alcohol 10:447-452, 1993 56. Irving MG, Booth CG, Devlin CM, et al: The effect of iron and ethanol on rat hepatocyte collagen synthesis. Comp Biochem Physiol A Physiol 100:583-590, 1991 57. Jenkins PM, Portmann BP, Edleston ALWF, et al: Use of polyunsaturated phosphatidylcholine choline in HBsAg negative chronic active hepatitis: Results of a prospective double blind control trial. Liver 2:77-81, 1982 57a. Kanner J, Hare1 S, Granit R Nitric oxide as an antioxidant. Arch Biochem Biophys 289~130-136,1991 58. Kawase T, Kato S, Lieber CS: Lipid peroxidation and antioxidant defense systems in rat liver after chronic ethanol feeding. Hepatology 10:815-821, 1989 59. Keiding S, Badsberg JH, Becker U, et al: The prognosis of patients with alcoholic liver disease: An international randomized, placebo-controlled trial on the effect of malotilate on survival. J Hepatol 20456460, 1994 60. Kimbel KA: Effects of ( + ) cyanidanol-3. Lancet 1:737, 1982 61. Kovach G, Salamon F: Effects of ( + )-cyanidan013 on chronic liver injury. Acta Physiol Hung 64:443448,1984 61a. Kubes P, Suzuki M, Granger DN: Nitric oxide: An endgenous modulator of leukocyte adhesion. Proc Natl Acad Sci U S A. 875139-5197, 1990 62. Leevy CM: Cirrhosis in alcoholics. Med Clin North Am 52:1445-1451, 1968 63. Lieber CS: Pathogenesis and treatment of liver fibrosis in alcoholics: 1996 Update [review]. Dig Dis 15:42-66, 1997 64. Lieber CS: Role ofoxidative stress and antioxidant therapy in alcoholic and nonalcoholic liver disease. Adv Pharmacol 38:601-628, 1997 65. Lieber CS, Casini A, DeCarli LM, et al: S-Adenosyl-L-methionine attenuates alcoholinduced liver injury in the baboon. Hepatology 11:165-172, 1990 66. Leiber CS, DeCarli LM, Ma KM, et al: Attenuation of alcoholic induced hepatic fibrosis by polyunsaturated lecithin. Hepatology 12:1390-1398, 1990 67. Leiber CS, Leo MA, Ihak KM, et al: Choline fails to prevent liver fibrosis in ethanol fed baboons but causes toxicity. Hepatology 5:561-572, 1985 68. Leiber CS, Robins SJ, Leo MA: Hepatic phosphatidyl ethanolamine methyl transferase activity is decreased by ethanol and increased by phosphatidylcholine. Alcoholism Clin Exp Res 18:592-595, 1994 69. Leiber CS, Robins SJ, Li J, et al: Phosphatidyl choline protects against fibrosis and cirrhosis in the baboon. Gastroenterology 106:152-159, 1994 70. Li JJ, Kim CI, Leo MA, et al: Polyunsaturated lecithin prevents acetaldehyde mediated hepatic collagen accumulation by stimulating collagenase activity in cultured hepatocytes. Hepatology 15:373-381, 1992 71. Lin SC, Lin YH, Chen CF, et al: The hepatoprotective and therapeutic effects of propolis ethanol extract on chronic alcohol induced liver injuries. Am J Clin Med 25:325-332, 1997 72. Lu SC: Methione adenosyl transferase and liver disease: It’s all about SAM. Gastroenterology 114:403407, 1998 72a. Ma TT, Ischiropoulos H, Brass C A Endotoxin stimulated nitric oxide production

878

MULLEN & DASARATHY

increases liver injury and reduces rat liver chemiluminescence during reperfusion. Gastroenterology 108:463469, 1995 73. Majumdar SK, Shaw GK, OGorman P, et al: The effect of Naftidrofuryl on ethanolinduced liver damage in chronic alcoholic patients. Drug- Alcohol Depend 10135142, 1982 74. Marshall AW, Graul RS, Morean MY, et al: Treatment of alcohol-related liver disease with thioctic' acid: A six m&th randomized double blind trial. Gut 23:108&1093, 1982 75. Marshall JB, Bumett DA, Zetterman RK, et al: Clinical and biochemical course of alcoholic liver disease following sudden discontinuation of alcohol consumption. Alcohol Clin Exp Res 7312-315, 1983 76. Mato IM, Camara J, Ortiz PK, et a1 S-Adenosyl methionine in the treatment of alcoholic liver cirrhosis: Results from a multicenter placebo controlled, randomized double blind clinical trial. Hepatology 26:251A, 1997 77. Maynaud A, Grand M, Belleville M: The effects of naftidrofuryl on cerebral energy metabolism. Extract Therapeutics 30:777-778, 1975 78. McHutchison JG, Runyon BA, Draguesleu JO, et al: Pentoxyfylline may prevent renal impairment (hepatorenal syndrome) in severe acute alcoholic hepatitis. Hepatology 1496A, 1991 79. Mezey E: Alcoholic liver disease. Prog Liver Dis 7555572, 1982 80. Mezey E: Treatment of alcoholic liver disease. Semin Liver Dis 13:210-216, 1993 81. Minok GY, Gauthier T, Zhang X, et a1 Ciprofloxacin reverses the inhibitory effects of acute ethanol exposure on hepatic regeneration in the rat. Hepatology 20:317A, 1994 82. Mira L, Silva M, Manso C F Scavenging of reactive oxygen species by silibinii dihemisuccinate. Biochem Pharmacol 48:753-759, 1994 83. Moller S, Becker U, Gronbaek M, et al: Short-term effect of recombinant human growth hormone in patients with alcoholic cirrhosis. J Hepatol 21:710-717, 1994 84. Morgan MY The prognosis and outcome of alcoholic liver disease. Alcohol Alcohol 29 (Cuppl 1):335-i43,-1994 85. Morean MY: Hepatoprotective agents in alcoholic liver disease. In Tvastruu N, OlssEn R (eds): ~ 1 ~ 0 6and 0 1 DisGse. Acta Medica Scandinavia SymposiGrn geries No 1. Uppsala, Almquist and Wiksell, 1985, pp 225233 86. Morgan MY The treatment of alcoholic hepatitis. Alcohol Alcohol 32:117-134, 1996 87. Morimoto M, Hagbjork AL, Wan YJY, et al: Modulation of experimental alcoholinduced liver disease by cytochrome P450 2E1 inhibitors. Hepatology 21:1610-1617, 1995 88. Mutimer D, Brunner H, Berthelol P, et al: Malotilate in alcoholic hepatitis-lessons from 3 European controlled trials [abstract]. Hepatology 8:1411, 1988 89. Nanji AA, Dannenberg AJ, Bass NM: Dietary fat composition influences cell injury in experimental alcoholic liver disease and has divergent effects on the expression of liver fatty acid binding protein and enzymes of extramitochondrial fatty acid oxidation. Gastroenterology 110:A1274, 1996 90. Nanji AA, Greenberg SS, Tahan SR, et al: Nitric oxide production in experimental alcoholic liver disease in the rat: Role in protection from injury. Gastroenterology 109~899-907,1995 91. Nanji AA, Mia0 L, Thomas P, et al: Increased cyclooxygenase-2 (Cox2) expression in Kupffer cells correlates with pathologic injury in experimental alcoholic liver disease. Gastroenterology 110:A1274, 1996 92. Nanji AA, Rahemtulla A, Mia0 L, et a1 Treatment with dietary saturated fatty acids improves liver pathology despite continued ethanol administration. Gastroenterology 110:A1275, 1996 93. Nanji AA, Sadrzadeh SM, Khettry U, et al: Protective effects of a novel quinone derivative (2E)-3-[5-(2,3dimethoxy-6-methyl-l,4-benzoquinoyl)]-2nonyl-2-propanoic acid on experimental alcoholic liver injury. J Pharmacol Exp Therap 266:1085-1090, 1993 94. Nanji AA, Sadrzadeh SM, Yang EK, et a 1 Dietary saturated fatty acids: A novel treatment for alcoholic liver disease. Gastroenterology 109:547-554, 1995 95. Nanji AA, Yang EK, Fogt F, et al: Medium chain triglycerides and vitamin E reduce Y

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

879

the severity of established experimental alcoholic liver disease. J Pharmacol Exp Ther 2771694-1700, 1996 96. Nanji AA, Zakim D, Rahemtulla A, et a1 Dietary saturated fatty acids down-regulate cyclooxygenase-2 and tumor necrosis factor alfa and reverse fibrosis in alcoholinduced liver disease in the rat. Hepatology 261538-1545, 1997 97. Nanji AA, Zhao S, Khwaja S, et al: Cimetidine prevents alcoholic hepatic injury in the intragastric feeding rat models. J Pharmacol Exp Ther 2692332-837, 1994 98. Navder KP, Baraona E, Lieber C S Polyenylphosphatidylcholine attenuates alcoholinduced fatty liver and hyperlipemia in rats. J Nutr 1271800-1806, 1997 99. Neuman MG, Cameron RG, Shear NH, et al: Effect of tauroursodeoxycholic and ursodeoxycholic acid on ethanol-induced cell injuries in the human Hep G2 cell line. Gastroenterology 109:555-563, 1995 100. Nichols JC, Bronk SF, Mellgren RL, et al: Inhibition of non-lysosomal calcium dependent proteolysis by glycine during anoxic injury of rat hepatocytes. Gastroenterol 104168-176, 1994 100a. Nishida J, McCuskey RS, McDonnell D et al: Protective role of NO in hepatic microcirculatory dysfunction during endtoxemia. Am J Physiol 267G113541141, 1994 101. Oide H, Thurman RG: Hepatic Ito cells contain calcium channels: Increase with transforming growth factor B-1. Hepatology 20:1009-1016, 1994 102. Osman E, Owen JS, Burroughs AJ: S-Adenosyl L methionine-a new therapeutic agent in liver disease? Aliment Pharmacol Ther 721-28, 1993 103. Palmas S: Treatment of alcoholic cirrhosis with ( + ) cyanidanol-3. In Con HO (ed): International Workshop on ( + ) cyanidanol-3 in Diseases of the Liver. Royal Society of Medicine Internal Congress and Symposium Series, No 67. London, Royal Society of Medicine, 1981, pp 167-171 104. Panos MZ, Polson R, Johnson R, et al: Polyunsaturated phosphatidylcholine for acute alcoholic hepatitis: A double blind randomized placebo controlled trial. Eur J Gastroenterol Hepatol 2:351-355, 1990 105. Pares S, Caballeria J, Bruguera M, et al: Histological course of alcoholic hepatitis: Influence of abstinence, sex and extent of hepatic damage. J Hepatol 2:3342, 1986 106. Pares A, Planas R, Torres M, et al: Effects of silymarin in alcoholic patients with cirrhosis of the liver: Results of a controlled double-blind randomized and multicenter trial. J Hepatol 28:615421, 1998 107. Peck RG, Lefer AM: Protective effects of nifedipine in the hypoxic perfused cat liver. Agents Actions Suppl 11:119-126, 1981 108. Pietrangelo A, Borella F, Casalgrandi G, et al: Antioxidant activity of silybin in vivo during long-term iron overload in rats. Gastroenterology 109:1941-1949, 1995 109. Plevris JN, Hayes PC, Bouchier IAD: Ursodeoxycholic acid in the treatment of alcoholic liver disease. Eur J Gastroenterol Hepatol3:653-656, 1991 110. Plomteux G, Albert A, Heusghem C: Hepatoprotector actions of silymarin in human acute viral hepatitis. RCS Journal of Medicine 5:259, 1977 111. Poupon RE, Lindor KD, Cauch-Dudek K, et al: Combined analysis of randomized controlled trials of ursodeoxycholic acid in primary biliary cirrhosis. Gastroenterology 113:884-890, 1997 112. Qu W, Zhong Z , Goto M, et al: Kupffer cell prostaglandin E2 stimulates parenchymal cell 0, consumption: Effect of alcohol treatment on cell-cell communication. Am J Physiol270G5746580,1996 112a. Radi R, Beckman JS, Bush KM, et al: Peroxynitrite induced membrane lipid peroxidation: The cytotoxic potential of superoxide and nitric oxide. Arch Biochem Biophys 288:481487, 1991 112b. Radomski MW, Palmer RMJ, Moncada S: An arginine/nitric oxide pathway present in human platelets regulates aggregation. Proc Natl Acad Sci USA 875193-5197,1990 113. Rastogi R, Saksena S, Garg NK, et a1 Picroliv protects against alcohol-induced chronic hepatotoxicity in rats. Planta Med 62283-285, 1996 113a. Richter C, Gogvadze V, Schlapbach R, et al: Nitric oxide kills hepatocytes by mobilizing mitochondria1 calcium. Biochem Biophys Res Commun 205:1143-1150, 1994 114. Rolachon A, Cordier L, Bacq Y, et al: Ciprofloxacin and long-term prevention of

880

MULLEN & DASARATHY

spontaneous bacterial peritonitis: Results of a prospective controlled trial. HepatolOgy 22:1171-1174, 1995 115. Rubin RA, Herrine SK, Zerin MA: Treatment of alcoholic hepatitis with d-a-tocopherol, polyethylene glycol 1000 succinate. Gastroenterology 110:A1308, 1996 116. Ryle PR, Broillet A, Perri S, et al: A comparative study of the effects of ( + ) catechin and 3-palmitoyl ( + ) catechin on alcohblic fatty liver in the rat. Alcohol Alcohol 18:239-248, 1983 117. Sadrzadeh SMH, Hall E, Nanji AA: Prevention of necrosis and inflammation in experimental alcoholic liver disease by a novel antioxidant lazeroid is associated with absence of TNF alpha mRNA and normalization of membrane of calcium at pase. Gastroenterology 110:A1309, 1996 118. Sadzaradeh SMH, Hallaway PE, Khettry U, et al: Macromolecular deferoxamine fails to protect against ethanol induced hepatic injury. Hepatology 20:358A, 1994 119. Sadrzadeh SMH, Hallaway PE, Nanji AA: The long-acting parenteral iron chelator, hydroxyethyl starch-deferoxamine, fails to protect against alcohol-induced liver injury in rats. J Pharmacol Exp Ther 280:1038-1042, 1997 120. Sadrzadeh SMH, Maydani M, Khettry U, et al: High dose vitamin E supplementation has no effect on ethanol induced pathological liver injury. Hepatology 20:316A, 1994 121. Saez-Royuela F, Lopez-Vasquez A, Lopez-Morante A, et al: Pentoxifylline induced acute hepatitis. J Hepatol 23:482484, 1995 122. Salmi HA, Sarna S: Effect of silymarin on chemical, functional, and morphological alterations of the liver. A double-blind controlled study. Scand J Gastroenterol 17517-521, 1982 123. Sanches-Tapias JM, Fiol 8,Rodes J: ( + ) cyanidanol-3 in mild alcoholic hepatitis. In Conn HO (ed): International workshop on ( + ) cyanidanol-3 in Diseases of the Liver. Royal Society of Medicine Internal Congress and Symposium series, No 67. London, Royal Society of Medicine, 1981, pp 173-175 124. Savier E, Shedlofsky SI, Swim AT, et al: The calcium channel blocker nisoldipine minimizes the release of tumor necrosis factor and interleukin 6 following rat liver transplantation. Transpl Int 5:398402, 1992 125. Segarnick DJ, Mandio Cordasco D, Agura V, et al: Gamma-linolenic acid inhibits the development of the ethanol-induced fatty liver. Prostaglandins Leuko Essent Fatty Acids 17277-282, 1985 126. Sherlock S: Alcoholic liver disease. Lancet 345227-229, 1995 127. Sherman DIN, Williams R Liver damage: Mechanism and management. Br Med Bull 50:126-138, 1994 128. Siegers CP, Pauli V, Korb G, et al: Hepato protection by malolitate against carbon tetrachloride-alcohol induced liver fibrosis. Agents Actions Suppl 18:600-603, 1986 129. Skakun NP, Moseichuk IP, Gil' lala. The efficacy of vitogepat and sirepar in combination with karsil in chronic liver lesions [Russian]. Eksp Klin Farmakol55:61-63, 1992 130. Steinberg EN: N acetyl cysteine may improve clinical outcome in acute alcoholic hepatitis. Gastroenterology 110:A1334, 1996 131. Takahara E, Ohta S, Hirobe M: Stimulatory effects of Silibinin on the DNA synthesis in partially hepatectomized rat livers: Non-response in hepatoma and other malignant cell lines. Biochem Pharmacol 35:538-541, 1986 132. Takei Y, Marzi I, Kauffman FC, et al: Prevention of early graft failure by the calcium channel blocker nisoldipine: Involvement of Kupffer cells. Transplantation 5034-20, 1990 133. Thurman RG, Ape1 E, Badr M, et al: Protection of liver by calcium entry blockers. Ann N Y Acad Sci 522:757-770, 1988 134. Trinchet JC, Coste T, Levy VG, et al: Treatment of alcoholic hepatitis with silymarin. A double-blind comparative study in 116 patients [French]. Gastroenterologie Clinique Biologique 13:120-124, 1989 135. Trudell JR, Lin WQ, Chrystof DA, et al: Induction of HSP72 in rat liver by chronic ethanol consumption combined with exercise: Association with the prevention of ethanol-induced fatty liver by exercise. Alcoholism Clin Exp Res 19:753-758, 1995 136. Tsukamoto He, Goal K, French SW Insights into the pathogenesis of alcoholic liver necrosis and fibrosis. Status report. Hepatology 12599408, 1990

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

881

137. Tuchweber B, Sieck R, Trost W Prevention by silybinin of phalloidin induced acute hepatotoxicity. Toxicol Appl Pharmacol 51:265-275, 1979 138. Ugarte A, Bunout D, Hurriaga H: Effect of ( + ) cyanidanol-3 on alcoholic liver disease with and without overt liver failure. In Conn HO (ed): International workshop on ( + ) cyanidanol-3 in Diseases of the Liver. Royal Society of Medicine Internal Congress and Symposium series, No 67. London, Royal Society of Medicine, 1981, pp 181-183 139. Umar L, Augusti KT, Joseph PK: Hypolipidemic action of cabbage oil in ethanol fed rats. Indian J Biochem Biophys 26:241-243, 1987 140. Valenzuela A, Barria T, Guerra R, et al: Inhibitory effect of the flavonoid silymarin on the erythrocyte hemolysis induced by phenylhydrazine. Biochem Biophys Res Commun 126:712-718, 1985 141. Varga M, Buris L: Some morphometric evidence of hepatoprotective effects of (+)cyanidanol-3. Pharmacology, Biochemistry & Behavior 33:523-526, 1989 142. Vendermiale G, Altomare E, Trizzio T, et al: Effects of oral S-adenosyl L-methionine on hepatic glutathione in patients with liver disease. Scand J Gastroenterol 24:407415, 1989 143. Vogel G, Tuchweber B, Trost W, et al: Protection by silybinin against Amanita phalloides intoxication in beagles. Toxicol Appl Pharmacol 73:355-362, 1984 144. Von Herbay A, de Groot H, Hegi U, et al: Low vitamin E content in plasma of patients with alcoholic liver disease, hemochromatosis, and Wilson’s disease. J Hepato1 20:4146, 1994 145. Wang JF, Greenberg SS, Spitzer JJ: Chronic alcohol administration stimulates nitric oxide formation in the rat liver with or without pretreatment with LPS. Hepatology 20:316A, 1994 146. Watkins T, Lenz P, Gapor A, et al: Gamma-tocotrienol as a hypocholesterolemic and antioxidant agent in rats fed atherogenic diets. Lipids 28:1113-1118, 1993 147. Watson WH, Chawla RK: S-Adenosylmethionine modulates biosynthesis of tumor necrosis factor in murine macrophage cells [abstract]. Hepatology 26:A395, 1997 148. Wickramsinghe SN, Hasan R In vitro effects of vitamin C, thioctic acid and dihydrolipoic acid on the cytotoxicity of post ethanol serum. Biochem Pharmacol 43:403411, 1992 149. World MJ, Aps EJ, Shaw GK, et al: (+)-cyanidan013 for alcoholic liver disease: Results of a six-month clinical trial. Alcohol & Alcoholism 19:23-29, 1984 150. World MJ, Ryle PR, Aps EJ, et al: Palmitoyl-catechin for alcoholic liver disease: Results of a three-month clinical trial. Alcohol Alcohol 22:331-340, 1987 151. World MJ, Thomson AD, Shaw G K Effects of ( + ) cyanidanol-3. Lancet 1:737, 1982 152. Worowski K, Chyczewski L, Skrzydlewska E: Histopathological evaluation of protective effect of L-cysteine in ethanol-induced liver damage in rats [Polish]. Rocz Akad Med Bialymst 35-36119-127, 1990-91 153. Yamazaki T, Nakajima Y, Niho Y, et al: Pharmacological studies on Puerariae fios 111: Protective effects of kakkalide on ethanol-induced lethality and acute hepatic injury in mice. J Pharm Pharmacol49:831-833, 1997 153a. Yoshizumi M, Perella MA, Bumett JC, et al: Tumor necrosis factor downregulates an endothelial nitric oxide synthase mRNA by shortening its half life. Circ Res 73:205-209, 1993 154. Yuki D, Thurman RG: The swift increase in alcohol metabolism. Time course for the increase in hepatic oxygen uptake and the involvement of glycolysis. J Biochem 186~119-126,1980 155. Zhong Z, Thurman RG: Glycine minimizes reperfusion injury in a low flow, reflow liver reperfusion model in the rat. Am J Physiol 270:G332-G338, 1996

Address reprint reqiiests to Kevin D. Mullen, MD, FRCPI MetroHealth Medical Center 2500 MetroHealth Drive41 Division Cleveland, OH 44109