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Glucosamine sulfate in osteoarthritis of the knee
and Cartilage (1994) 2, 51-59
.O•e•arthritis !STE0ARTHRITIS ~ 1994 Osteoarthritis Research Society
1063-4584/94/010051 +09 $08.00/0
and
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CARTILAGE Glucosamine
s u l f a t e in o s t e o a r t h r i t i s o f t h e k n e e
BY WOLFGANG NOACK*, MICHAEL FISCHERt, KLAUS K. F6RSTER$, L u c I o C. ROVATI§ AND IVO SETNIKAR§
*Department of Orthopedics-Evangelisches Waldkrankenhaus, Berlin, Germany; t Institute for Numerical Statistics GmbH, K61n, Germany; SDepartment of Clinical Research, Opfermann Arzneimittel GmbH, Wiehl, Germany; §Department of Clinical Pharmacology, Rotta Research Laboratorium, Monza (MI), Italy Summary Glucosamine sulfate is a drug used for the treatment of osteoarthritis (OA), based on its pharmacological and metabolic activities on the cartilage and chondrocytes, complemented by mild anti-inflammatory properties and a favorable pharmacokinetic profile. The ain~of this study was to define the activity and safety of glucosamine sulfate on the symptoms of patients with OA, using a multicenter, randomized, placebo-controlled, double-blind, parallel-group study design. The study included 252 outpatients with OA of the knee (Lequesne's criteria), radiological stage between I and III, and Lequesne's severity index of at least 4 points and symptoms for at least 6 months. Patients were treated with either placebo or o r a l glucosamine sulfate 500 mg t.i.d, for 4 weeks, with weekly clinic visits. Responders to treatment were defined a s patients with a reduction of at least 3 points in the Lequesne's index with a positive overall assessment by the investigator. The Lequesne's index was 10.6 + 0.45 S.E.M. points in both groups at the start of the study. This decreased to 7.45 + 0.5 points in the treatment group (average 3.2) and 8.4+__0.4 points in the placebo group (avErage 2.2) (P < 0.05, Student's t-test). The responder rate in the evaluable patients was 55% with glucosamine (N = 120) vs 38% with placebo (N = 121). These proportions were 52% vs 37% in an intention-to-treat analysis (P = 0.014 and 0.016, respectively; Fisher's Exact Test). The medications were well tolerated throughout the study, with no difference between the glucosamine and placebo treated groups. It is concluded that glucosamine sulfate may be a safe and effective symptomatic Slow Acting Drug for OA. Key words: Glucosamine sulfate, Osteoarthritis, Gonarthrosis, Therapy. have been labeled sym pt om at i c 'Slow A c t i n g Drugs in O s t e o a r t h r i t i s ' [5]. Glucosamine is an a m i n o - m o n o s a c c h a r i d e a n d one of t he basic c o n s t i t u e n t s of t he d i s a c c h a r i d e u n i t s of a r t i c u l a r cart i l age glycosaminoglycans. Roden's in vitro studies [6] showed t h a t e x o g e n o u s glucosamine stimulated the u p t a k e of 35SOj, a m a r k e r of g l y c o s a m i n o g l y c a n synthesis by t h e chondrocytes. L a t e r studies d e m o n s t r a t e d t h a t glucosamine could increase t he synthesis of glycos a m i n o g l y c a n in cartilage c u l t u r e s [7] a n d stimulate in vitro and ex vivo t he u p t a k e of asSO~- a n d of aH-prol~ne by the a r t i c u l a r c a r t i l a g e o f th e r a t femoral head [8, 9], suggesting t h a t glucosamine is able n o t only to st i m ul at e g l y c o s a m i n o g l y c a n production, but also t he synthesis of proteoglycans as a whole. This c o n c l u s i o n was confirmed by r e c e n t d o s e - r e s p o n s e e x p e r i m e n t s in h u m a n c h o n d r o c y t e cultures [10]. T hese p h a r m a c o l o g i c a l properties are probably s u p p o r t e d in vivo by glucosamine elective i n c o r p o r a t i o n in t he a r t i c u l a r cart i l age after systemic adm i ni st rat i on, as demonst rat ed by animal p h a r m a c o k i n e t i c studies using radiolabeled glucosamine [I1, 12]. Based on the above d a t a and on the promising
Introduction
(OA) is the most common a r t i c u l a r r h e u m a t i c disease. Different t r e a t m e n t s h a v e been proposed to c o n t r o l its symptoms and in some instances even its progression. Among the p h a r m a c o l o g i c a l approaches, nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used for symptom relief [1]. T h e use of NSAIDs is often limited by t he i r side-effect p a t t e r n , as well as by u n c e r t a i n t i e s a b o u t t h e i r effects on the e vol ut i on of the disease [2]. D u r i n g th e last few decades, different categories of new p h a r m a c o l o g i c a l agents h a v e been proposed to be specifically active in OA, e i t h e r t h r o u g h a direct m e c h a n i s m of action on t he metabolism of the a r t i c u l a r cartilag~ and/ or by interfering with th e disease processes [3, 4]. Recently, t h e I n t e r n a t i o n a l L e a g u e Against R h e u m a t i s m (ILAR) has produced a classification and set of guidelines for testing some of these drugs, t h a t OSTEOARTHRITIS
Submitted 2 November 1993; accepted 22 December 1993. Address correspondence to: Dr Lucio Rovati, Department of Clinical Pharmacology, Rotta Research Laboratorium, Via Valosa di Sopra 7/9, 20052 Monza (Milano), Italy.
51
52
N o a c k et al.: G l u c o s a m i n e v s p l a c e b o in k n e e OA
results obtained in some models of experimental OA [13], glucosamine sulfate (the glucosamine salt actually used for pharmacological and clinical purposes) has been proposed for therapeutic use in OA. Several small controlled clinical studies have shown promising results on short-term control of the symptoms of the disease [14-19]. While ongoing long-term trials are testing w h e t h e r the drug is able to modify the evolution of OA, the aim of the present clinical investigation was to confirm the effectiveness of oral glucosamine sulfate in comparison with placebo in ameliorating OA symptoms (basically pain and limitation of motion) over a short-term t r e a t m e n t course, utilizing validated efficacy scales.
Materials
and methods
PATIENTS
Two hundred and fifty-two ambulatory patients of both sexes with OA of the knee (gonarthrosis) were enrolled in the study. They were over 18 years of age and they were suffering from uni- or bilateral OA of the knee with pain and limitation of motion, but without overt laboratory (ESR < 30 mm/h) or clinical (i.e. joint swelling, effusion, erythema, palpable increase in temperature) signs of inflammation at the affected joint(s). Osteoarthritis of the knee was defined according to the diagnostic criteria of Lequesne [20], t h a t include both clinical and radiological criteria. At enrolment, the patients underwent a full medical examination, including medical history, with particular regard to the involved knee joint(s). Radiographs in the weight-bearing antero-posterior view, lateral and axial views were obtained at enrolment. The clinical stage was classified according to Weseloh and Liebig [21], ranging between I (transient symptoms) and III (continuous symptoms). The radiological staging, from Stage I to Stage IV, was performed according to the classification proposed by J~ger and Wirth [22], which is a slight modification of the grading introduced by Kellgren and Lawrence [23], mainly t a k i n g into account the progressive narrowing of the joint space, the increase in subchondral sclerosis, the appearance of osteophytes and subchondral cysts. The symptoms of OA of the knee had to be present for at least 6 months prior to enrolment and the patients had to be able to walk. The index of severity according to Lequesne [24] had to be at least 4 points. Major exclusions were: a radiological stage below I or above III; intra-articular corticosteroids within the previous 2 months; NSAID use within
the previous 2 weeks; recent t r a u m a or lesions of the involved knee(s); significant hematological disorder, hepatic or renal a b n o r m a l i t y at laboratory screening; extreme under- or overweight (Broca index < 75 or > 150). All exclusions present in Lequesne's criteria [20] were systematically considered, with p a r t i c u l a r regard to inflammatory rheumatic diseases, metabolic arthropathies and, in any case, r h e u m a t i c diseases other t h a n OA. NSAIDs, analgesics, corticosteroids, or other treatments for OA, including any physical therapy, were not allowed during the study. Other treatments for concomitant diseases were allowed, but had to be recorded. STUDY DESIGN
AND
EVALUATIONS
The study was conducted according to a multicenter, randomized, placebo-controlled, doubleblind design on two parallel groups of patients. The total duration of the study was 4 weeks. Clinic visits were performed at enrolment and at weekly intervals thereafter. At each visit the patient's clinical status was assessed by the algofunctional index of Lequesne [24]. This is a combined score of pain (at night, after immobilization, standing, walking, getting up from sitting position; point score: 0-2), maximum walking distance (from 'more t h a n 1 km, but limited': 1 point, to 'less t h a n 100 m': 6 points) and movement limitation in some activities of daily living (going up o r down a standard flight of stairs, squatting, walking on uneven ground; point score: 0-2), obtained according to a standardized interview. In this study, pain scores of patients with bilateral involvement were referred to the most affected knee. At the end of treatment, the investigator also gave an overall judgement of efficacy rated as ~good', ~moderate', 'unchanged', or 'worse'. Safety was assessed by routine laboratory tests (including hematology, clinical chemistry and urinalysis) performed at enrolment and at the end of t r e a t m e n t in a centralized laboratory; heart rate, blood pressure in the sitting position and body weight were measured at each weekly visit. Adverse events spontaneously reported by the patients following a general question were recorded t h r o u g h o u t the study period and classified for their severity (mild, moderate, severe). Nine orthopedic and rheumatologic clinics in the Berlin area participated in the study. The study was performed in accordance with the ethical principles of the Helsinki Declaration. Ethical a p p r o v a l was given by the Ethical Board of the
O s t e o a r t h r i t i s and C a r t i l a g e Vol. 2 N o . 1
Arztekammer, Berlin and the study was conducted to Good Clinical Practice standards according to the guidelines in force in G e r m a n y when the study was s t a r t e d [25]. All patients gave their written informed cgnsent to participate in the study. DRUGS
Sugar-coated tablets of 250 mg glucosamine sulfate each (DONA ® ' 200-S; Opfermann Arzneimittel GmbH, D-5276 Wiehl, Germany) were u s e d . Placebo consisted of indistinguishable tablets containing only excipients. The drug regimen was 2 tablets three times a day (1500 rag/day of glucosamine sulfate), at meals, every day for 4 weeks. STATISTICS
The necessary number of patients to be enrolled was calculated according to the Fisher's twotailed Exact Probability test on the assumption of an alpha error of 0.05, a beta error of 0.20, and an estimated success rate of about 40% with placebo and about 60% with glucosamine sulfate. The total number of patients t h a t was therefore considered necessary, t a k i n g into account a drop-out rate of 10-15~/o for any reason, was 125 patients per group. The patients were randomized by means of a computer software in blocks of four (two on glucosamine sulfate, two on placebo) for series of 28 patients in each center. The success rate was based on the number of patients who were ~responders' to the treatment. Responders were considered those patients who, at the end of treatment, had a decrease in Lequesne's index of at least 3 points, in the presence of an overall judgement of efficacy by the investigator rated ~good' or ~moderate'. The Fisher's two-tailed Exact Probability test was used to compare the success rate between the two treatment groups in the principal analysis for efficacy. This analysis was performed both on patients who completed the t r e a t m e n t course according to the protocol and by the 'intention-totreat' approach, t h a t is including all eligible patients, regardless of compli~nce with the protocol, or drop-out for any reason, in order to avoid a possible bias [26]. For the descriptive statistics purposes, the Lequesne's index data were computed as arithmetic mean with standard error and range: a statistical analysis for the difference between the two groups at the end of t r e a t m e n t was performed by the Student's t-test. Comparison between the two patient populations with regard to demo-
53
graphic variables was performed by the Student's t-test or the chi-squared test, as appropriate. The rates of adverse events and of drop-outs because of adverse events were compared by the Fisher's test. The results of laboratory tests performed at enrolm e n t and at the end of t r e a t m e n t were compared by the McNemar Shift test. All tests were performed at the 95% significance level. Results
One h u n d r e d and twenty-six patients in each group were enrolled in the study. The glucosamine sulfate group consisted of 52 men and 74 women, while there were 48 men and 78 women in the placebo group. The characteristics of the p a t i e n t population are shown in Table I, and the two groups were comparable with regard to sex, age, height, body weight, localization of OA of the knee (mono- or bilateral), radiological and clinical stages, and d u r a t i o n of symptoms. EFFICACY
One hundred and twenty patients in the glucosamine group and 121 in the placebo group completed the study and could be evaluated for efficacy. The remaining patients could be evaluated only in the intention-to-treat analysis, for the following reasons: three patients in the glucosamine group and two in the placebo group did not r e t u r n for follow-up after enrolment; one patient receiving glucosamine and two under placebo discontinued the t r e a t m e n t before the first control visit because of adverse events (drop-outs occurring later could be evaluated for efficacy); three further patients had to be excluded for protocol violation, since the complaints were too mild (Lequesne's index below 4 points) at enrolment. The average Lequesne's index was 10.6 in both groups at the beginning of t r e a t m e n t and it decreased progressively during the study (Table II). The mean decrease was 3.2 points in the glucosamine group and 2.2 points in the placebo group. There was a statistically significant difference between the two t r e a t m e n t groups in favor of glucosamine at the end of the 4 weeks of t r e a t m e n t (Table II). There were 66 (55%) 'responders' among the 120 evaluable patients belonging to the glucosamine sulfate group, while there were 46 responders out of the 121 placebo treated patients (38%). This difference in the main criterion of efficacy is statistically significant (P = 0.014), as shown in Table III. When referred to the ~intended-to-treat'
54
N o a c k et al.: G l u c o s a m i n e v s placebo in k n e e OA
Table I Characteristics of the patient population
No. of patients Age (yrs) Age classes < 50 yrs 50-65 yrs >65yrs Height (cm) Weight (kg) Localization Left Right Bilateral Radiological stage I II III Clinical stage 1 2 3 4 Duration of symptoms: Not known or < 6 months 6-12 months 1-2 years 2 10 years > 10 years
Glucosamine sulfate
Placebo
126 M = 52 (41%) W = 74 (59%) 55 +_14 (22-84)
126 M = 48 (38%) W = 78 (62%) 55 +_15 (17-85)
43 M = 24 W = 19 45 M = 17 W = 28 38M=llW=27 168_+ 9 (149-190) 75 + 12 (50-110)
43 M = 24 W = 19 47 M = 18 W = 29 36M--6 W=30 168_+ 9 (147-186) 74_+ 12 (45-110)
29 (23%) 41 (33%) 56 (44%)
42 (33%) 38 (30%) 46 (37%)
43 (34%) 48 (38°//0) 35 (28%)
43 (34%) 49 (39%) 34 (27%)
40 (32°//0) 64 (51%) 21 (17%) 1 (<1%)
44 (35%) 56 (44%) 25 (20%) 1(<1%)
5 22 16 64 19
3 29 21 59 14
(4%) (17%) (13%) (51°//o) (15%)
2%) (23%) (17%) (47%) (11%)
D a t a a r e r e p o r t e d a s a b s o l u t e v a l u e s ( w i t h p e r c e n t a g e s in p a r e n t h e s e s ) , or as m e a n _+S.D. ( w i t h ranges in parentheses). M = men, W = women.
p o p u l a t i o n , t h e r e w e r e 52% ~responders' in t h e g l u c o s a m i n e t r e a t e d g r o u p a n d o n l y 37% in t h e p l a c e b o g r o u p ( P - - 0.016) (Table III). T h e p r o p o r t i o n of r e s p o n d e r p a t i e n t s w a s s i m i l a r to t h e a b o v e o v e r a l l r e s u l t e v e n w h e n a n a l y z e d for t h e d i f f e r e n t s e v e r i t y classes, i.e. grouping the patients according to their
Table II Lequesne's index at enrolment and at each weekly examination
Week 0 1 2 3 4
Glucosamine sulfate 10.6__+0.4 10.0__+0.4 8.8___0.4 7.9+_0.4 7.4_+0.5*
(4-22) (0-26) (0-21) (0-20) (0-21)
:::: :::~::Mean ~:S:;E.M., r a n g e i n p a r e n t h e s e s . • :: ~ : ~: 0 ~ 5 ~ s plac:ebo, g r o u p .
.... :::::::::::::::::::::::::::::: ::::::?:::~ ::
Placebo 10.6_+0.4 (4-20) 10.1_+0.3(2-24) 9.3_+0.4 (0-24) 8.6_+0.4 (0-24) 8.4_+0.4 (0-24)
Lequesne's index value at enrolment (data not shown). SAFETY
T h e n u m b e r of p a t i e n t s w h o r e p o r t e d a d v e r s e events, and those who dropped out from the study b e c a u s e of t h e s e a d v e r s e e v e n t s , is r e p o r t e d in T a b l e IV. T h e r e w e r e e i g h t p a t i e n t s (6%) in t h e glucosamine group complaining about adverse events: five p a t i e n t s h a d m i n o r g a s t r o i n t e s t i n a l disturbances (including epigastric pain/discomfort, or n a u s e a , or d i a r r h e a ) , t w o r e p o r t e d heada c h e a n d o n e a n e p i s o d e of l o c a l i z e d itching. I n five of t h e s e p a t i e n t s (4~/o) t h e t r e a t m e n t w a s discontinued. I n t h e p l a c e b o group, 13 p a t i e n t s (10%) r e p o r t e d the following adverse events: six p a t i e n t s c o m p l a i n e d of m i n o r g a s t r o i n t e s t i n a l d i s t u r b a n c e s (including epigastric pain, heartburn, nausea, d i a r r h e a ) , t w o h a d h e a d a c h e , t h r e e i t c h i n g or minor skin reaction episodes and two circulatory
Osteoarthritis and Cartilage Vol. 2 No. 1
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Table III Number and percentage of patients who were 'responders" to the treatment in the glucosamine sulfate and placebo groups
Glucosamine sulfate Responders No. % Evaluable population 'Intended-to-treat' population
66/120 66/126
Placebo Responders No. %
55% 52%
46/121 46/126
38% 37%
P value 0.014 0.016
The P values were calculated by the Fisher's two-tailed Exact Probability test. Table IV Adverse events reported during the study
Adverse event Gastrointestinal disturbances Pruritus or skin reactions Headache Circulatory disturbances Total
Glucosamine sulfate
Placebo
5 (3) 1 (0) 2 (2) 0 (0) 8 (5)
6 (5) 3 (2) 2 (1) 2 (0) 13 (8)
The number of patients with adverse events is reported. In parentheses are the number of drop-outs related to adverse events. troubles (low blood pressure and r e c u r r e n t h e a r t failure, respectively). In eight of these patients (6%) the t r e a t m e n t was discontinued. All the above reported adverse events were transient and of mild to moderate severity. The difference between the two t r e a t m e n t groups with regard to adverse events and related drop-out rate was not significant. No statistically nor clinically significant changes were observed either in the mean values or in the individual d a t a for the laboratory tests and vital signs (data not shown). Discussion
In this double-blind, randomized, placebocontrolled study we have shown t h a t oral glucosamine sulfate (1500 mg/day) was significantly more effective t h a n placebo in improving pain and movement limitation in patients with OA of the knee over a 4-week t r e a t m e n t course. On the other hand, there were no differences between the two t r e a t m e n t groups with respect to the occurrence of adverse events. Tolerability was good in both groups t h r o u g h o u t the study. Different drugs reportedly having specific actions on OA have been proposed [3, 4]: few of them are chemically defined entities, while the majority are undefined macromolecular extracts from animal cartilage. This implies t h a t these
extracted products may contain antigenic impurities and t h a t they must be administered parenterally or even intra-articularly, in order to be bioavailable at the articular site. Several mechanisms of action have been suggested for these compounds, including the stimulation of glycosaminoglycan synthesis and the inhibition of proteolytic enzymes [27-33]. A beneficial activity has also been shown in experimental models of OA [34-37]. Glucosamine sulfate is unique in its features, being a chemically well-defined and pure substance, with a small molecular weight (456.42). In the body, glucosamine sulfate dissociates into sulfate ions and D-glucosamine (molecular weight: 179.17), which at 37°C has a pKa of 6.91. These chemico-physical properties account for its favorable pharmacokinetic profile, t h a t includes oral bioavailability, as has been shown in rats and dogs [11, 12] using uniformly labeled [14C]-glucosamine, and confirmed in h u m a n s by cold methods [12] and recently using the labeled compound [38]. I n vitro, glucosamine sulfate has been shown to stimulate glycosaminoglycan and proteoglycan synthesis [7-10], but with a p a t t e r n of activity t h a t seemed to be particularly favorable, in t h a t the chromatographic profiles of the proteoglycans extracted from the intercellular matrix of h u m a n chondrocyte clusters were comparable to naturally occurring proteoglycans in terms of molecular
56
N o a c k e t al.: Glucosamine v s p l a c e b o i n knee OA
weight and complex formation with hyaluronic acid [39]. In older experiments, glucosamine has been shown to be active in some experimental animal models of OA [13] and able to exert a protective activity against the metabolic and morphologic damages induced on chondrocytes by dexamethasone [40], or on cartilage by certain NSAIDs [8]. Besides these specific actions at the cartilage level and on chondrocyte metabolism, glucosamine sulfate has been shown to inhibit the effects of several proflogistic agents in vivo [41] and to be orally effective in experimental models of generalized subacute inflammation, or arthritis [42]. These anti-inflammatory effects were achieved without inhibiting the synthesis of prostaglandins but showing an ability to block the generation of superoxide radicals by macrophages and the activity of lysosomal enzymes [41]. Conversely, the drug did not show a direct analgesic activity [41]. Based on the expanding knowledge of the normal homeostatic mechanisms exerted by different endogenous substances, such as some cytokines and growth factors, and the ability of some drugs to mimic experimentally these activities, the agents pharmacologically active on the cartilage have been tentatively labeled as ~chondroprotective' in the past. This concept has been extensively reviewed [43]. Unfortunately, since most of these activities could be shown only in experimental models, this term has been misused to indicate also the clinical effects of these compounds and this has been misleading. The recent guidelines proposed and still under revision by the ILAR [5] try to put order in this confused matter and clearly distinguish between the symptomatic activity of Slow Acting Drugs for OA and their possible, but a s yet undemonstrated in humans, disease modifying activity (replacing the term ~chondroprotection'). Indeed, the clinical demonstration of activity of these agents has been focused mostly on their ability to ameliorate the symptoms of OA over short- or medium-term treatment courses [44-49]. Nevertheless, even the shortterm results are not conclusive, since most of the existing studies suffer from inadequate study design and evaluation methods [5]. Glucosamine sulfate has been granted approval in several European countries and a wide clinical experience has been achieved during the recent years [3, 4]. We performed the present investigation, in order to validate existing studies [14-19] using present-day study design. I n this' study, the treatment with glucosamine sulfate resulted in a significantly higher improve....~:::i:rate::::::(55% glucosamine compared to 38%
placebo). The size of the two t r e a t m e n t groups allowed us to detect this almost 99% significant difference with an 80% statistical power. The 55% improvement rate for glucosamine sulfate in this study is consistent with that found in other trials of conventional drug treatments of OA [50-53]. The overall result did not change even with intended-to-treat analysis. The patient population was selected according to codified diagnostic criteria [20]; it is remarkable that the favorable results for glucosamine were obtained irrespective of the stage of the disease (i.e. all slight/moderate clinical and radiological stages being represented). The majority of the enrolled patients were women, as expected, and all relevant age classes were well represented. In addition, it is worth noting that there was a considerable proportion, over 30%, of elderly patients ( > 65 years). Our results could then be extrapolated to the usual population which is encountered in the common clinical practice. It is also interesting to note that the proportion of responder patients was similar, independent of symptom severity at enrolment. The main evaluation criterion for efficacy was based on the Lequesne's index of severity of knee OA, which is a balanced score that takes into a c c o u n t pain, maximum walking distance and limitation of motion in common activities of daily living [24]. This index has been validated: interobserver reproducibility is good and in drug trials it is more sensitive to change than conventional indices [24]. The average index score of our patient population at enrolment was consistent with baseline values of moderate severity and allowed reliable assessment of treatment [24, 54]. Indeed, we observed a mean decrease of 3.2 points under glucosamine, consistent with the original validation data for t r e a t m e n t of symptomatic knee OA [24, 54]. The beneficial effects of glucosamine sulfate developed slowly over time, taking an average of 2 to 3 weeks before observation of a significant clinical improvement. This behavior was confirmed in another 4-week study, in which glucosamine was compared to ibuprofen in 200 patients [55]. Although not tested in the present trial, other recent preliminary data in OA of the knee and of other joints [56, 57] indicate that the clinical improvement induced by glucosamine sulfate lasts after the drug is discontinued. The possibility of observing carry-over effects prevents the use of the cross-over design in clinical trials. The tolerability of glucosamine sulfate in this study was good and comparable to that of placebo. In recent years, the tolerability of extracted
O s t e o a r t h r i t i s and Cartilage Vol. 2 N o . 1 macromolecular anti-osteoarthritis drugs has been q u e s t i o n e d for s e v e r a l r e a s o n s , i n c l u d i n g i m m u n o l o g i c a l r e a c t i o n s a n d h e p a r i n o i d effects [58, 59]. G l u c o s a m i n e s u l f a t e is a c h e m i c a l l y defined, s m a l l and pure molecule, devoid of antigenic properties, or u n s p e c i f i c p h a r m a c o l o g i c a l a c t i o n s . I t s o r a l a n d parenteral tolerability has been confirmed by this and other recently performed clinical trials [55-57], a s w e l l as b y t h e w i d e g e n e r a l c l i n i c a l e x p e r i e n c e [4]. I n c o n c l u s i o n , o u r r e s u l t s s u g g e s t t h a t glucosamine sulfate complies with the requisites proposed by I L A R f o r a s y m p t o m a t i c S l o w A c t i n g D r u g in O s t e o a r t h r i t i s [5], in t h a t it s e l e c t i v e l y r e l i e v e s t h e s y m p t o m s of t h e disease, w i t h a d e l a y o f a few w e e k s in t h e o n s e t of its a c t i o n w h i c h is t h e n sustained throughout treatment. Other observat i o n s [56, 57] a l s o s u g g e s t t h a t t h i s effect t e n d s to l a s t a f t e r d r u g d i s c o n t i n u a t i o n . I t is difficult to conclude by which of the reviewed mechanisms t h e d r u g e x e r t s a f a v o r a b l e a c t i v i t y o n O A symptoms. T h e r e f o r e , f u r t h e r e x p e r i m e n t a l s t u d i e s a r e n e e d e d for a b e t t e r u n d e r s t a n d i n g o f t h e m e c h a n i s m of a c t i o n o f t h e drug. N e w c l i n i c a l t r i a l s a r e a l s o n e c e s s a r y a n d a r e u n d e r w a y in o r d e r to c o n f i r m t h e s y m p t o m a t i c effects o f g l u c o s a m i n e s u l f a t e o v e r l o n g e r t h e r a p e u t i c c o u r s e s , to b e t t e r define t h e k i n e t i c s of its effects, i n c l u d i n g t h e d u r a t i o n of t h e r e s i d u a l effect a f t e r t r e a t m e n t disc o n t i n u a t i o n , a n d to t e s t t h e p o s s i b i l i t y of conc o m i t a n t a d m i n i s t r a t i o n w i t h o t h e r d r u g s ( s u c h as N S A I D s , or o t h e r s ) . I n l i n e w i t h t h e r e c e n t I L A R guidelines [5], long-term placebo-controlled clinical studies with objective evaluation criteria a r e also in p r o g r e s s [60] to s t u d y g l u c o s a m i n e s u l f a t e ' s p o t e n t i a l for d i s e a s e m o d i f i c a t i o n in OA.
5.
6. 7.
8.
9.
10. 11.
12. 13. 14. 15.
Acknowledgements T h e a u t h o r s e x p r e s s t h e i r t h a n k s to t h e Investigators of the different centers in B e r l i n - - D r s R. B o r c h a r d t , J. B u r g e r , K. D i t t m a r , B. G a u d i n , H.-J. G i f f h o r n , D. R o g m a n s , M. T a l k e , M. W a l d e n a n d W. v o n Z e z s c h w i t z - - w h o c o l l a b o r a t e d in t h i s m u l t i c e n t e r s t u d y . References
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Willkens RF, Dahl SLI Eds. Therapeutic controversies in the rheumatic diseases. Orlando, CA: Grune & Stratton 1987:213-51. Bird H. The current treatment of osteoarthritis. In: Russel RGG, Dieppe PA, Eds. Osteoarthritis: current research and prospects for pharmacological intervention. London: IBC Ltd 1991:173-95. Lequesne M. ILAR guidelines for testing Slow Acting Drugs in Osteoarthritis (SADOAs). In: Proceedings of the XVHIth ILAR Congress of Rheumatology. Rev Esp Reumatol 1993;20(Suppl 1):220-1. Roden L. Effect of hexosamines on the synthesis of chondroitin sulphuric acid in vitro. Arkh Kemi 1956;10:345-52. Karzel K, Domenjoz R. Effects of hexosamine derivatives and uronic acid derivatives on glycosaminoglycan metabolism of fibroblast cultures. Pharmacology 1971;5:337-45. Vidal y Plana RR, Bizzarri D, Rovati AL. Articular cartilage pharmacology. In vitro studies on glucosamine and non steroidal antiinflammatory drugs. Pharmacol Res Comm 1978;10:557-69. Vidal y Plana RR, Karzel K. Glucosamine: its role in the articular cartilage metabolism 2. Studies on rat and h u m a n articular cartilage. Fortschr Med 1980;98:8014. ) Bassleer C, Henrotin Y, Franchimont P. In-vitro evaluation of drugs proposed as chondroprotective agents. Int J Tissue React 1992;14:231-41. Setnikar I, Giachetti C, Zanolo G. Absorption, distribution and excretion of radioactivity after a single intravenous or oral administration of [t4C]-glucosamine to the rat. Pharmatherapeutica 1984;3:538-50. Setnikar I, Giachetti C, Zanolo G. Pharmacokinetics of glucosamine in the dog and in man. Arzneimittelforschung 1986; 36: 729-35. Eichler J, Noh E. Therapy of deforming arthrosis through the action upon the cartilagineous metabolism. Orthopprax 1970;9:225-9. Crolle G, D'Este E. Glucosamine sulfate for the management of arthrosis: a controlled clinical investigation. Curr Med Res Opin 1980;7:104-9. Drovanti A, Bignamini AA, Rovati AL. Therapeutic activity of oral glucosamine sulfate in osteoarthritis: a placebo controlled double-blind investigation. Clin Ther 1980;3:260-72. Mund-Hoym WD. Medical treatment of spinal arthrosis with glucosamine or phenylbutazone. A controlled study. Therapiewoche 1980;30:5922-8. Pujalte JM, Llavore EP, Ylescupidez FR. Double-blind clinical evaluation of oral glucosamine sulfate in the basic treatment of osteoarthrosis. Curr Med Res Opin 1980;7:110-14. D'Ambrosio E, Casa B, Bompani R, Scali G, Scali M. Glucosamine sulfate: a controlled clinical investigation in arthrosis. Pharmatherapeutica 1981;2:504-8. Lopez Vaz A. Double-blind clinical evaluation of the relative efficacy of ibuprofen and glucosamine sulfate in the management of osteoarthrosis of the knee in out-patients. Curr Med Res Opin 1982;8:145-9. Lequesne MG. Clinical features, diagnostic criteria, functional assessment and radiological classifications of osteoarthritis. Rheumatol Int 1982;7:1-10.
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21. Weseloh G, Liebig K. Therapeutic aspects in degenerative joint destruction. Orthopade 1983;12:127-34. 22. J~ger M, Wirth CJ, Eds. Kapselbandldsionen: Biomechanik, Diagnostik und Therapie. Stuttgart: Georg Thieme Verlag 1978. 23. Kellgren JH, Lawrence JS. Radiological assessment of osteoarthritis. A n n Rheum Dis 1957;16:494-501. 24. Lequesne MG, Mery C, Samson M, Gerard P. Indexes of severity for osteoarthritis of the hip and knee. Validation-Value in comparison with other assessment tests. Scand J Rheumatol 1987;16 (Suppl 65): 85-9. 25. Sander A. Principles for the proper conduct of clinical drug trials (translated from Bundesanzeiger 243, 1987, p. 16617). Drugs made in Germany 1989;32:21-3. 26. Pocock SJ. Protocol deviations. In: Pocock SJ, Ed. Clinical trials: a practical approach. Chichester: J Wiley 1983:176-86. 27. Bollet AJ. Stimulation of protein-chondroitin sulfate synthesis by normal and osteoarthritic articular cartilage. Arthritis Rheum 1968;11:663-73. 28. Kalbhen DA, Karzel K, Domenjoz R. A high molecular mucopolysaccharide peptide complex stimulating connective tissue metabolism. Pharmacology 1968;1:33-42. 29. Nevo Z, Dorfman A. Stimulation of chondromucoprotein synthesis in chondrocytes by extracellular chondromucoprotein. Proc Natl Acad Sci USA 1972;69:2069-72. 30. Stancikova M, Trnavsky K, Keilova H. The effect of antirheumatic drugs on collagenolytic activity of cathepsin B 1. Biochem Pharmacol 1977;26:2121-4. 31. Baici A, Salgam P, Fehr K, Boni A. Inhibition of human elastase from polymorphonuclear leucocytes by a glycosaminoglycan polysulfate (Arteparon). Biochem Pharmacol 1980;29:1723-7. 32. Adam M, Krabcova M, Musilova J, Pesakova V, Brettschneider I, Deyl A. Contribution to the mode of action of glycosaminoglycanpolysulphate (GAGPS) upon human osteoarthritic cartilage. Arzneimittelforschung 1982;3{}:1730-2. 33. Burkhardt D, Ghosh P. Laboratory evaluation of antiarthritis drugs as potential chondroprotective agents. Semin Arthritis Rheum 1987;17:3-34. 34. Altman RD, Dean DD, Muniz OE, Howell DS. Prophylactic treatment of canine osteoarthritis with glycosaminoglycan polysulfuric acid ester. Arthritis Rheum 1989;32:759-66. 35. Altman RD, Dean DD, Muniz OE, Howell DS. Therapeutic treatment of canine osteoarthritis with glycosaminoglycan polysulfuric acid ester. Arthritis Rheum 1989;32:1300-7. 36. Dean DD, . Muniz OE, Rodriquez I et al. Amelioration of lapine osteoarthritis by treatment with glycosaminoglycan-peptide association complex (Rumalon). Arthritis Rheum 1991;34:304-13. 37. Alti~an RD, Gottlieb NL, Howell DS, Eds. Hyaluronan. Semin Arthritis Rheum 1993;22(Suppl 1):1-51. 38. Setnikar I, Palumbo R, Canali S, Zanolo G. Pharmacokinetics of glucosamine in man. Arzneimittelforschung 1993;43:1109-13. 39. Bassleer C, Reginster JY, Franchimont P. Effects of
glucosamine on differentiated human chondrocytes cultivated in cluster (Abstract). Rev Esp Reumatol 1993;20(Suppl 1):Mo 96. 40. Raiss R. Influence of glucosamine sulfate on experimentally impaired articular cartilage: test of ultrastructural changes in chondrocytes using morphometry. Fortschr Med 1985;103:658-62. 41. Setnikar I, Cereda R, Pacini MA, Revel L. Antireactive properties of glucosamine sulfate. Arzneimittelforschung 1991;41:157-61. 42. Setnikar I, Pacini MA, Revel L. Antiarthritic effects of glucosamine sulfate studied on animal models. Arzneimittelforschung 1991;41:542-5. 43. Ghosh P, Brooks P. Chondroprotection: exploring the concept. J Rheumatol 1991;18:161-6. 44. Adler E, Wolf~E, Taustein I. A double blind trial with cartilage and bone marrow extract in degenerative gonarthrosis. Acta Rheum Scand 1970;16:6-11. 45. Dixon AS, Kersley GD, Mercer R et al. A doubleblind controlled trial of Rumalon in the treatment of painful osteoarthrosis of the hip. A n n Rheum Dis 1970;29:193-4. 46. Denko CW. Treatment of osteoarthritis with Rumalon. Arthritis Rheum 1978;21:494-6. 47. Siegmeth W, Radi I. Comparison of glycosaminoglycan polysulfate and saline solution in arthrosis of the large joints. Z Rheumatol 1983;42:223-8. 48. Dixon AStJ, Jacoby RK, Berry H, Hamilton EBD. Clinical trial of intraarticular injection of sodium hyaluronate in patients with osteoarthritis of the knee. Curr Med Res Opin 1988;11:205-13. 49. Grecomoro G, Martorana V, Di Marco C. Intra-articular treatment with sodium hyalurohate in gonarthrosis. Controlled clinical trial versus placebo. Pharmatherapeutica 1987;5:137-41. 50. Anderson JJ, Firschein HE, Meenan FR. Sensitivity of a healthy status measure to short-term clinical changes in arthritis. Arthritis Rheum 1989;32:844-50. 51. Tyson VCH, Glynne A. A comparative study of benoxaprofen and ibuprofen in osteoarthritis in general practice. J Rheumatol Suppl 1980;6:132-8. 52. Levinson DJ, Rubinstein HM. Double-blind comparison of fenoprofen calcium and ibuprofen in osteoarthritis of large joints. Curr Ther Res 1983;34:280-4. 53. Bradley JD, Brandt KD, Katz BP, Kalasinski LA, Ryan SI. Comparison of an antiinflammatory dose of ibuprofen, an analgesic dose of ibuprofen, and acetaminophen in the treatment of patients with osteoarthritis of the knee. N Engl J Med 1991;325:87-91. 54. Lequesne M, Samson M, Gerard P, Mery C. Algo-functional indices for the follow-up of hip and knee arthrosis. Rev R h u m Mal Osteoartic 1990;57:32S-36S. 55. Muller-FaBbender H, Bach GL, Haase W, Rovati LC, Setnikar I. Glucosamine sulfate compared to ibuprofen in osteoarthritis of the knee. Osteoarthritis Cart 1994;2:61-9. 56. Rovati LC, Setnikar I, Fbrster KK, Reichelt A, Noack W. Glucosamine sulfate in gonarthrosis: efficacy in placebo controlled studies. (Abstract). Rev Esp Reumatol 1993;20(Suppl 1):72. 57. Giacovelli G, Rovati LC. Clinical efficacy of glucosamine sulfate in osteoarthritis of the
O s t e o a r t h r i t i s and Cartilage V o L 2 No. 1
spine. (Abstract). Rev Esp Reumatol 1993;20(Suppl 1):Mo 96. 58. Berg PA, Dfirk H, Saal J, Hopf G. Bovine cartilage and marrow extract. Lancet 1989;1:1275. 59. Greiling H. Biochemical studies of potentially antiarthrotid~drugs. Z Rheumatol 1983;42:153-8.
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60. Serni U. Profile of glucosamine sulfate as an example of Slow Acting Drug in Osteoarthritis. In: Proceedings of the XVIIIth ILAR Congress of Rheumatology~ Rev Esp Reumatol 1993;20(Suppl 1):222.
.O•e•arthritis !STE0ARTHRITIS ~ 1994 Osteoarthritis Research Society
1063-4584/94/010051 +09 $08.00/0
and
.....
CARTILAGE Glucosamine
s u l f a t e in o s t e o a r t h r i t i s o f t h e k n e e
BY WOLFGANG NOACK*, MICHAEL FISCHERt, KLAUS K. F6RSTER$, L u c I o C. ROVATI§ AND IVO SETNIKAR§
*Department of Orthopedics-Evangelisches Waldkrankenhaus, Berlin, Germany; t Institute for Numerical Statistics GmbH, K61n, Germany; SDepartment of Clinical Research, Opfermann Arzneimittel GmbH, Wiehl, Germany; §Department of Clinical Pharmacology, Rotta Research Laboratorium, Monza (MI), Italy Summary Glucosamine sulfate is a drug used for the treatment of osteoarthritis (OA), based on its pharmacological and metabolic activities on the cartilage and chondrocytes, complemented by mild anti-inflammatory properties and a favorable pharmacokinetic profile. The ain~of this study was to define the activity and safety of glucosamine sulfate on the symptoms of patients with OA, using a multicenter, randomized, placebo-controlled, double-blind, parallel-group study design. The study included 252 outpatients with OA of the knee (Lequesne's criteria), radiological stage between I and III, and Lequesne's severity index of at least 4 points and symptoms for at least 6 months. Patients were treated with either placebo or o r a l glucosamine sulfate 500 mg t.i.d, for 4 weeks, with weekly clinic visits. Responders to treatment were defined a s patients with a reduction of at least 3 points in the Lequesne's index with a positive overall assessment by the investigator. The Lequesne's index was 10.6 + 0.45 S.E.M. points in both groups at the start of the study. This decreased to 7.45 + 0.5 points in the treatment group (average 3.2) and 8.4+__0.4 points in the placebo group (avErage 2.2) (P < 0.05, Student's t-test). The responder rate in the evaluable patients was 55% with glucosamine (N = 120) vs 38% with placebo (N = 121). These proportions were 52% vs 37% in an intention-to-treat analysis (P = 0.014 and 0.016, respectively; Fisher's Exact Test). The medications were well tolerated throughout the study, with no difference between the glucosamine and placebo treated groups. It is concluded that glucosamine sulfate may be a safe and effective symptomatic Slow Acting Drug for OA. Key words: Glucosamine sulfate, Osteoarthritis, Gonarthrosis, Therapy. have been labeled sym pt om at i c 'Slow A c t i n g Drugs in O s t e o a r t h r i t i s ' [5]. Glucosamine is an a m i n o - m o n o s a c c h a r i d e a n d one of t he basic c o n s t i t u e n t s of t he d i s a c c h a r i d e u n i t s of a r t i c u l a r cart i l age glycosaminoglycans. Roden's in vitro studies [6] showed t h a t e x o g e n o u s glucosamine stimulated the u p t a k e of 35SOj, a m a r k e r of g l y c o s a m i n o g l y c a n synthesis by t h e chondrocytes. L a t e r studies d e m o n s t r a t e d t h a t glucosamine could increase t he synthesis of glycos a m i n o g l y c a n in cartilage c u l t u r e s [7] a n d stimulate in vitro and ex vivo t he u p t a k e of asSO~- a n d of aH-prol~ne by the a r t i c u l a r c a r t i l a g e o f th e r a t femoral head [8, 9], suggesting t h a t glucosamine is able n o t only to st i m ul at e g l y c o s a m i n o g l y c a n production, but also t he synthesis of proteoglycans as a whole. This c o n c l u s i o n was confirmed by r e c e n t d o s e - r e s p o n s e e x p e r i m e n t s in h u m a n c h o n d r o c y t e cultures [10]. T hese p h a r m a c o l o g i c a l properties are probably s u p p o r t e d in vivo by glucosamine elective i n c o r p o r a t i o n in t he a r t i c u l a r cart i l age after systemic adm i ni st rat i on, as demonst rat ed by animal p h a r m a c o k i n e t i c studies using radiolabeled glucosamine [I1, 12]. Based on the above d a t a and on the promising
Introduction
(OA) is the most common a r t i c u l a r r h e u m a t i c disease. Different t r e a t m e n t s h a v e been proposed to c o n t r o l its symptoms and in some instances even its progression. Among the p h a r m a c o l o g i c a l approaches, nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used for symptom relief [1]. T h e use of NSAIDs is often limited by t he i r side-effect p a t t e r n , as well as by u n c e r t a i n t i e s a b o u t t h e i r effects on the e vol ut i on of the disease [2]. D u r i n g th e last few decades, different categories of new p h a r m a c o l o g i c a l agents h a v e been proposed to be specifically active in OA, e i t h e r t h r o u g h a direct m e c h a n i s m of action on t he metabolism of the a r t i c u l a r cartilag~ and/ or by interfering with th e disease processes [3, 4]. Recently, t h e I n t e r n a t i o n a l L e a g u e Against R h e u m a t i s m (ILAR) has produced a classification and set of guidelines for testing some of these drugs, t h a t OSTEOARTHRITIS
Submitted 2 November 1993; accepted 22 December 1993. Address correspondence to: Dr Lucio Rovati, Department of Clinical Pharmacology, Rotta Research Laboratorium, Via Valosa di Sopra 7/9, 20052 Monza (Milano), Italy.
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N o a c k et al.: G l u c o s a m i n e v s p l a c e b o in k n e e OA
results obtained in some models of experimental OA [13], glucosamine sulfate (the glucosamine salt actually used for pharmacological and clinical purposes) has been proposed for therapeutic use in OA. Several small controlled clinical studies have shown promising results on short-term control of the symptoms of the disease [14-19]. While ongoing long-term trials are testing w h e t h e r the drug is able to modify the evolution of OA, the aim of the present clinical investigation was to confirm the effectiveness of oral glucosamine sulfate in comparison with placebo in ameliorating OA symptoms (basically pain and limitation of motion) over a short-term t r e a t m e n t course, utilizing validated efficacy scales.
Materials
and methods
PATIENTS
Two hundred and fifty-two ambulatory patients of both sexes with OA of the knee (gonarthrosis) were enrolled in the study. They were over 18 years of age and they were suffering from uni- or bilateral OA of the knee with pain and limitation of motion, but without overt laboratory (ESR < 30 mm/h) or clinical (i.e. joint swelling, effusion, erythema, palpable increase in temperature) signs of inflammation at the affected joint(s). Osteoarthritis of the knee was defined according to the diagnostic criteria of Lequesne [20], t h a t include both clinical and radiological criteria. At enrolment, the patients underwent a full medical examination, including medical history, with particular regard to the involved knee joint(s). Radiographs in the weight-bearing antero-posterior view, lateral and axial views were obtained at enrolment. The clinical stage was classified according to Weseloh and Liebig [21], ranging between I (transient symptoms) and III (continuous symptoms). The radiological staging, from Stage I to Stage IV, was performed according to the classification proposed by J~ger and Wirth [22], which is a slight modification of the grading introduced by Kellgren and Lawrence [23], mainly t a k i n g into account the progressive narrowing of the joint space, the increase in subchondral sclerosis, the appearance of osteophytes and subchondral cysts. The symptoms of OA of the knee had to be present for at least 6 months prior to enrolment and the patients had to be able to walk. The index of severity according to Lequesne [24] had to be at least 4 points. Major exclusions were: a radiological stage below I or above III; intra-articular corticosteroids within the previous 2 months; NSAID use within
the previous 2 weeks; recent t r a u m a or lesions of the involved knee(s); significant hematological disorder, hepatic or renal a b n o r m a l i t y at laboratory screening; extreme under- or overweight (Broca index < 75 or > 150). All exclusions present in Lequesne's criteria [20] were systematically considered, with p a r t i c u l a r regard to inflammatory rheumatic diseases, metabolic arthropathies and, in any case, r h e u m a t i c diseases other t h a n OA. NSAIDs, analgesics, corticosteroids, or other treatments for OA, including any physical therapy, were not allowed during the study. Other treatments for concomitant diseases were allowed, but had to be recorded. STUDY DESIGN
AND
EVALUATIONS
The study was conducted according to a multicenter, randomized, placebo-controlled, doubleblind design on two parallel groups of patients. The total duration of the study was 4 weeks. Clinic visits were performed at enrolment and at weekly intervals thereafter. At each visit the patient's clinical status was assessed by the algofunctional index of Lequesne [24]. This is a combined score of pain (at night, after immobilization, standing, walking, getting up from sitting position; point score: 0-2), maximum walking distance (from 'more t h a n 1 km, but limited': 1 point, to 'less t h a n 100 m': 6 points) and movement limitation in some activities of daily living (going up o r down a standard flight of stairs, squatting, walking on uneven ground; point score: 0-2), obtained according to a standardized interview. In this study, pain scores of patients with bilateral involvement were referred to the most affected knee. At the end of treatment, the investigator also gave an overall judgement of efficacy rated as ~good', ~moderate', 'unchanged', or 'worse'. Safety was assessed by routine laboratory tests (including hematology, clinical chemistry and urinalysis) performed at enrolment and at the end of t r e a t m e n t in a centralized laboratory; heart rate, blood pressure in the sitting position and body weight were measured at each weekly visit. Adverse events spontaneously reported by the patients following a general question were recorded t h r o u g h o u t the study period and classified for their severity (mild, moderate, severe). Nine orthopedic and rheumatologic clinics in the Berlin area participated in the study. The study was performed in accordance with the ethical principles of the Helsinki Declaration. Ethical a p p r o v a l was given by the Ethical Board of the
O s t e o a r t h r i t i s and C a r t i l a g e Vol. 2 N o . 1
Arztekammer, Berlin and the study was conducted to Good Clinical Practice standards according to the guidelines in force in G e r m a n y when the study was s t a r t e d [25]. All patients gave their written informed cgnsent to participate in the study. DRUGS
Sugar-coated tablets of 250 mg glucosamine sulfate each (DONA ® ' 200-S; Opfermann Arzneimittel GmbH, D-5276 Wiehl, Germany) were u s e d . Placebo consisted of indistinguishable tablets containing only excipients. The drug regimen was 2 tablets three times a day (1500 rag/day of glucosamine sulfate), at meals, every day for 4 weeks. STATISTICS
The necessary number of patients to be enrolled was calculated according to the Fisher's twotailed Exact Probability test on the assumption of an alpha error of 0.05, a beta error of 0.20, and an estimated success rate of about 40% with placebo and about 60% with glucosamine sulfate. The total number of patients t h a t was therefore considered necessary, t a k i n g into account a drop-out rate of 10-15~/o for any reason, was 125 patients per group. The patients were randomized by means of a computer software in blocks of four (two on glucosamine sulfate, two on placebo) for series of 28 patients in each center. The success rate was based on the number of patients who were ~responders' to the treatment. Responders were considered those patients who, at the end of treatment, had a decrease in Lequesne's index of at least 3 points, in the presence of an overall judgement of efficacy by the investigator rated ~good' or ~moderate'. The Fisher's two-tailed Exact Probability test was used to compare the success rate between the two treatment groups in the principal analysis for efficacy. This analysis was performed both on patients who completed the t r e a t m e n t course according to the protocol and by the 'intention-totreat' approach, t h a t is including all eligible patients, regardless of compli~nce with the protocol, or drop-out for any reason, in order to avoid a possible bias [26]. For the descriptive statistics purposes, the Lequesne's index data were computed as arithmetic mean with standard error and range: a statistical analysis for the difference between the two groups at the end of t r e a t m e n t was performed by the Student's t-test. Comparison between the two patient populations with regard to demo-
53
graphic variables was performed by the Student's t-test or the chi-squared test, as appropriate. The rates of adverse events and of drop-outs because of adverse events were compared by the Fisher's test. The results of laboratory tests performed at enrolm e n t and at the end of t r e a t m e n t were compared by the McNemar Shift test. All tests were performed at the 95% significance level. Results
One h u n d r e d and twenty-six patients in each group were enrolled in the study. The glucosamine sulfate group consisted of 52 men and 74 women, while there were 48 men and 78 women in the placebo group. The characteristics of the p a t i e n t population are shown in Table I, and the two groups were comparable with regard to sex, age, height, body weight, localization of OA of the knee (mono- or bilateral), radiological and clinical stages, and d u r a t i o n of symptoms. EFFICACY
One hundred and twenty patients in the glucosamine group and 121 in the placebo group completed the study and could be evaluated for efficacy. The remaining patients could be evaluated only in the intention-to-treat analysis, for the following reasons: three patients in the glucosamine group and two in the placebo group did not r e t u r n for follow-up after enrolment; one patient receiving glucosamine and two under placebo discontinued the t r e a t m e n t before the first control visit because of adverse events (drop-outs occurring later could be evaluated for efficacy); three further patients had to be excluded for protocol violation, since the complaints were too mild (Lequesne's index below 4 points) at enrolment. The average Lequesne's index was 10.6 in both groups at the beginning of t r e a t m e n t and it decreased progressively during the study (Table II). The mean decrease was 3.2 points in the glucosamine group and 2.2 points in the placebo group. There was a statistically significant difference between the two t r e a t m e n t groups in favor of glucosamine at the end of the 4 weeks of t r e a t m e n t (Table II). There were 66 (55%) 'responders' among the 120 evaluable patients belonging to the glucosamine sulfate group, while there were 46 responders out of the 121 placebo treated patients (38%). This difference in the main criterion of efficacy is statistically significant (P = 0.014), as shown in Table III. When referred to the ~intended-to-treat'
54
N o a c k et al.: G l u c o s a m i n e v s placebo in k n e e OA
Table I Characteristics of the patient population
No. of patients Age (yrs) Age classes < 50 yrs 50-65 yrs >65yrs Height (cm) Weight (kg) Localization Left Right Bilateral Radiological stage I II III Clinical stage 1 2 3 4 Duration of symptoms: Not known or < 6 months 6-12 months 1-2 years 2 10 years > 10 years
Glucosamine sulfate
Placebo
126 M = 52 (41%) W = 74 (59%) 55 +_14 (22-84)
126 M = 48 (38%) W = 78 (62%) 55 +_15 (17-85)
43 M = 24 W = 19 45 M = 17 W = 28 38M=llW=27 168_+ 9 (149-190) 75 + 12 (50-110)
43 M = 24 W = 19 47 M = 18 W = 29 36M--6 W=30 168_+ 9 (147-186) 74_+ 12 (45-110)
29 (23%) 41 (33%) 56 (44%)
42 (33%) 38 (30%) 46 (37%)
43 (34%) 48 (38°//0) 35 (28%)
43 (34%) 49 (39%) 34 (27%)
40 (32°//0) 64 (51%) 21 (17%) 1 (<1%)
44 (35%) 56 (44%) 25 (20%) 1(<1%)
5 22 16 64 19
3 29 21 59 14
(4%) (17%) (13%) (51°//o) (15%)
2%) (23%) (17%) (47%) (11%)
D a t a a r e r e p o r t e d a s a b s o l u t e v a l u e s ( w i t h p e r c e n t a g e s in p a r e n t h e s e s ) , or as m e a n _+S.D. ( w i t h ranges in parentheses). M = men, W = women.
p o p u l a t i o n , t h e r e w e r e 52% ~responders' in t h e g l u c o s a m i n e t r e a t e d g r o u p a n d o n l y 37% in t h e p l a c e b o g r o u p ( P - - 0.016) (Table III). T h e p r o p o r t i o n of r e s p o n d e r p a t i e n t s w a s s i m i l a r to t h e a b o v e o v e r a l l r e s u l t e v e n w h e n a n a l y z e d for t h e d i f f e r e n t s e v e r i t y classes, i.e. grouping the patients according to their
Table II Lequesne's index at enrolment and at each weekly examination
Week 0 1 2 3 4
Glucosamine sulfate 10.6__+0.4 10.0__+0.4 8.8___0.4 7.9+_0.4 7.4_+0.5*
(4-22) (0-26) (0-21) (0-20) (0-21)
:::: :::~::Mean ~:S:;E.M., r a n g e i n p a r e n t h e s e s . • :: ~ : ~: 0 ~ 5 ~ s plac:ebo, g r o u p .
.... :::::::::::::::::::::::::::::: ::::::?:::~ ::
Placebo 10.6_+0.4 (4-20) 10.1_+0.3(2-24) 9.3_+0.4 (0-24) 8.6_+0.4 (0-24) 8.4_+0.4 (0-24)
Lequesne's index value at enrolment (data not shown). SAFETY
T h e n u m b e r of p a t i e n t s w h o r e p o r t e d a d v e r s e events, and those who dropped out from the study b e c a u s e of t h e s e a d v e r s e e v e n t s , is r e p o r t e d in T a b l e IV. T h e r e w e r e e i g h t p a t i e n t s (6%) in t h e glucosamine group complaining about adverse events: five p a t i e n t s h a d m i n o r g a s t r o i n t e s t i n a l disturbances (including epigastric pain/discomfort, or n a u s e a , or d i a r r h e a ) , t w o r e p o r t e d heada c h e a n d o n e a n e p i s o d e of l o c a l i z e d itching. I n five of t h e s e p a t i e n t s (4~/o) t h e t r e a t m e n t w a s discontinued. I n t h e p l a c e b o group, 13 p a t i e n t s (10%) r e p o r t e d the following adverse events: six p a t i e n t s c o m p l a i n e d of m i n o r g a s t r o i n t e s t i n a l d i s t u r b a n c e s (including epigastric pain, heartburn, nausea, d i a r r h e a ) , t w o h a d h e a d a c h e , t h r e e i t c h i n g or minor skin reaction episodes and two circulatory
Osteoarthritis and Cartilage Vol. 2 No. 1
55
Table III Number and percentage of patients who were 'responders" to the treatment in the glucosamine sulfate and placebo groups
Glucosamine sulfate Responders No. % Evaluable population 'Intended-to-treat' population
66/120 66/126
Placebo Responders No. %
55% 52%
46/121 46/126
38% 37%
P value 0.014 0.016
The P values were calculated by the Fisher's two-tailed Exact Probability test. Table IV Adverse events reported during the study
Adverse event Gastrointestinal disturbances Pruritus or skin reactions Headache Circulatory disturbances Total
Glucosamine sulfate
Placebo
5 (3) 1 (0) 2 (2) 0 (0) 8 (5)
6 (5) 3 (2) 2 (1) 2 (0) 13 (8)
The number of patients with adverse events is reported. In parentheses are the number of drop-outs related to adverse events. troubles (low blood pressure and r e c u r r e n t h e a r t failure, respectively). In eight of these patients (6%) the t r e a t m e n t was discontinued. All the above reported adverse events were transient and of mild to moderate severity. The difference between the two t r e a t m e n t groups with regard to adverse events and related drop-out rate was not significant. No statistically nor clinically significant changes were observed either in the mean values or in the individual d a t a for the laboratory tests and vital signs (data not shown). Discussion
In this double-blind, randomized, placebocontrolled study we have shown t h a t oral glucosamine sulfate (1500 mg/day) was significantly more effective t h a n placebo in improving pain and movement limitation in patients with OA of the knee over a 4-week t r e a t m e n t course. On the other hand, there were no differences between the two t r e a t m e n t groups with respect to the occurrence of adverse events. Tolerability was good in both groups t h r o u g h o u t the study. Different drugs reportedly having specific actions on OA have been proposed [3, 4]: few of them are chemically defined entities, while the majority are undefined macromolecular extracts from animal cartilage. This implies t h a t these
extracted products may contain antigenic impurities and t h a t they must be administered parenterally or even intra-articularly, in order to be bioavailable at the articular site. Several mechanisms of action have been suggested for these compounds, including the stimulation of glycosaminoglycan synthesis and the inhibition of proteolytic enzymes [27-33]. A beneficial activity has also been shown in experimental models of OA [34-37]. Glucosamine sulfate is unique in its features, being a chemically well-defined and pure substance, with a small molecular weight (456.42). In the body, glucosamine sulfate dissociates into sulfate ions and D-glucosamine (molecular weight: 179.17), which at 37°C has a pKa of 6.91. These chemico-physical properties account for its favorable pharmacokinetic profile, t h a t includes oral bioavailability, as has been shown in rats and dogs [11, 12] using uniformly labeled [14C]-glucosamine, and confirmed in h u m a n s by cold methods [12] and recently using the labeled compound [38]. I n vitro, glucosamine sulfate has been shown to stimulate glycosaminoglycan and proteoglycan synthesis [7-10], but with a p a t t e r n of activity t h a t seemed to be particularly favorable, in t h a t the chromatographic profiles of the proteoglycans extracted from the intercellular matrix of h u m a n chondrocyte clusters were comparable to naturally occurring proteoglycans in terms of molecular
56
N o a c k e t al.: Glucosamine v s p l a c e b o i n knee OA
weight and complex formation with hyaluronic acid [39]. In older experiments, glucosamine has been shown to be active in some experimental animal models of OA [13] and able to exert a protective activity against the metabolic and morphologic damages induced on chondrocytes by dexamethasone [40], or on cartilage by certain NSAIDs [8]. Besides these specific actions at the cartilage level and on chondrocyte metabolism, glucosamine sulfate has been shown to inhibit the effects of several proflogistic agents in vivo [41] and to be orally effective in experimental models of generalized subacute inflammation, or arthritis [42]. These anti-inflammatory effects were achieved without inhibiting the synthesis of prostaglandins but showing an ability to block the generation of superoxide radicals by macrophages and the activity of lysosomal enzymes [41]. Conversely, the drug did not show a direct analgesic activity [41]. Based on the expanding knowledge of the normal homeostatic mechanisms exerted by different endogenous substances, such as some cytokines and growth factors, and the ability of some drugs to mimic experimentally these activities, the agents pharmacologically active on the cartilage have been tentatively labeled as ~chondroprotective' in the past. This concept has been extensively reviewed [43]. Unfortunately, since most of these activities could be shown only in experimental models, this term has been misused to indicate also the clinical effects of these compounds and this has been misleading. The recent guidelines proposed and still under revision by the ILAR [5] try to put order in this confused matter and clearly distinguish between the symptomatic activity of Slow Acting Drugs for OA and their possible, but a s yet undemonstrated in humans, disease modifying activity (replacing the term ~chondroprotection'). Indeed, the clinical demonstration of activity of these agents has been focused mostly on their ability to ameliorate the symptoms of OA over short- or medium-term treatment courses [44-49]. Nevertheless, even the shortterm results are not conclusive, since most of the existing studies suffer from inadequate study design and evaluation methods [5]. Glucosamine sulfate has been granted approval in several European countries and a wide clinical experience has been achieved during the recent years [3, 4]. We performed the present investigation, in order to validate existing studies [14-19] using present-day study design. I n this' study, the treatment with glucosamine sulfate resulted in a significantly higher improve....~:::i:rate::::::(55% glucosamine compared to 38%
placebo). The size of the two t r e a t m e n t groups allowed us to detect this almost 99% significant difference with an 80% statistical power. The 55% improvement rate for glucosamine sulfate in this study is consistent with that found in other trials of conventional drug treatments of OA [50-53]. The overall result did not change even with intended-to-treat analysis. The patient population was selected according to codified diagnostic criteria [20]; it is remarkable that the favorable results for glucosamine were obtained irrespective of the stage of the disease (i.e. all slight/moderate clinical and radiological stages being represented). The majority of the enrolled patients were women, as expected, and all relevant age classes were well represented. In addition, it is worth noting that there was a considerable proportion, over 30%, of elderly patients ( > 65 years). Our results could then be extrapolated to the usual population which is encountered in the common clinical practice. It is also interesting to note that the proportion of responder patients was similar, independent of symptom severity at enrolment. The main evaluation criterion for efficacy was based on the Lequesne's index of severity of knee OA, which is a balanced score that takes into a c c o u n t pain, maximum walking distance and limitation of motion in common activities of daily living [24]. This index has been validated: interobserver reproducibility is good and in drug trials it is more sensitive to change than conventional indices [24]. The average index score of our patient population at enrolment was consistent with baseline values of moderate severity and allowed reliable assessment of treatment [24, 54]. Indeed, we observed a mean decrease of 3.2 points under glucosamine, consistent with the original validation data for t r e a t m e n t of symptomatic knee OA [24, 54]. The beneficial effects of glucosamine sulfate developed slowly over time, taking an average of 2 to 3 weeks before observation of a significant clinical improvement. This behavior was confirmed in another 4-week study, in which glucosamine was compared to ibuprofen in 200 patients [55]. Although not tested in the present trial, other recent preliminary data in OA of the knee and of other joints [56, 57] indicate that the clinical improvement induced by glucosamine sulfate lasts after the drug is discontinued. The possibility of observing carry-over effects prevents the use of the cross-over design in clinical trials. The tolerability of glucosamine sulfate in this study was good and comparable to that of placebo. In recent years, the tolerability of extracted
O s t e o a r t h r i t i s and Cartilage Vol. 2 N o . 1 macromolecular anti-osteoarthritis drugs has been q u e s t i o n e d for s e v e r a l r e a s o n s , i n c l u d i n g i m m u n o l o g i c a l r e a c t i o n s a n d h e p a r i n o i d effects [58, 59]. G l u c o s a m i n e s u l f a t e is a c h e m i c a l l y defined, s m a l l and pure molecule, devoid of antigenic properties, or u n s p e c i f i c p h a r m a c o l o g i c a l a c t i o n s . I t s o r a l a n d parenteral tolerability has been confirmed by this and other recently performed clinical trials [55-57], a s w e l l as b y t h e w i d e g e n e r a l c l i n i c a l e x p e r i e n c e [4]. I n c o n c l u s i o n , o u r r e s u l t s s u g g e s t t h a t glucosamine sulfate complies with the requisites proposed by I L A R f o r a s y m p t o m a t i c S l o w A c t i n g D r u g in O s t e o a r t h r i t i s [5], in t h a t it s e l e c t i v e l y r e l i e v e s t h e s y m p t o m s of t h e disease, w i t h a d e l a y o f a few w e e k s in t h e o n s e t of its a c t i o n w h i c h is t h e n sustained throughout treatment. Other observat i o n s [56, 57] a l s o s u g g e s t t h a t t h i s effect t e n d s to l a s t a f t e r d r u g d i s c o n t i n u a t i o n . I t is difficult to conclude by which of the reviewed mechanisms t h e d r u g e x e r t s a f a v o r a b l e a c t i v i t y o n O A symptoms. T h e r e f o r e , f u r t h e r e x p e r i m e n t a l s t u d i e s a r e n e e d e d for a b e t t e r u n d e r s t a n d i n g o f t h e m e c h a n i s m of a c t i o n o f t h e drug. N e w c l i n i c a l t r i a l s a r e a l s o n e c e s s a r y a n d a r e u n d e r w a y in o r d e r to c o n f i r m t h e s y m p t o m a t i c effects o f g l u c o s a m i n e s u l f a t e o v e r l o n g e r t h e r a p e u t i c c o u r s e s , to b e t t e r define t h e k i n e t i c s of its effects, i n c l u d i n g t h e d u r a t i o n of t h e r e s i d u a l effect a f t e r t r e a t m e n t disc o n t i n u a t i o n , a n d to t e s t t h e p o s s i b i l i t y of conc o m i t a n t a d m i n i s t r a t i o n w i t h o t h e r d r u g s ( s u c h as N S A I D s , or o t h e r s ) . I n l i n e w i t h t h e r e c e n t I L A R guidelines [5], long-term placebo-controlled clinical studies with objective evaluation criteria a r e also in p r o g r e s s [60] to s t u d y g l u c o s a m i n e s u l f a t e ' s p o t e n t i a l for d i s e a s e m o d i f i c a t i o n in OA.
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