- Email: [email protected]
Leflunomide-induced acute hepatitis
Digestive and Liver Disease 36 (2004) 82–84
Brief Clinical Observation
Leflunomide-induced acute hepatitis C. Sevilla-Mantilla a , L. Ortega b , J.A.G. Agúndez c , B. Fernández-Gutiérrez d , J.M. Ladero a,∗ , M. D´ıaz-Rubio a a
Service of Gastroenterology, Hospital Cl´ınico San Carlos, Complutense University, Ciudad Universitaria, Madrid 28040, Spain b Service of Pathology, Hospital Cl´ınico San Carlos, Complutense University, Madrid, Spain c Department of Pharmacology, University of Extremadura, Badajoz, Spain d Service of Rheumatology, Hospital Cl´ınico San Carlos, Complutense University, Madrid, Spain Received 7 April 2003; accepted 16 June 2003
Abstract Leflunomide, a new immunomodulatory agent, was prescribed to a 67-year-old female patient with rheumatoid arthritis. Fifteen days later she developed diarrhoea and elevated liver enzymes. A liver biopsy showed a pattern of acute hepatitis. The patient was homozygous for the rare CYP2C9*3 allele, which determines the slowest metabolic rate for CYP2C9 enzymatic activity, that is probably involved in the metabolism of leflunomide. Liver damage subsided in few weeks. This case illustrates the risk of hepatotoxicity by leflunomide and suggests that it is possibly related to CYP2C9 polymorphism. © 2003 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved. Keywords: CYP2C9; Genetic polymorphism; Leflunomide
1. Introduction Leflunomide is a new immunomodulatory agent that inhibits the enzyme dihydroorotate dehydrogenase, responsible for the de novo synthesis of pyrimidine-containing ribonucleotides. Activated T lymphocytes are especially sensitive to the effect of the drug [1]. Leflunomide has been approved for the treatment of rheumatoid arthritis and it is available in many countries as 20 mg tablets. Leflunomide is a prodrug that is almost completely converted into its active metabolite, A77 1726, through firstpass metabolism in the gut wall and the liver. Such activation seems to be mediated by several enzymatic and nonenzymatic mechanisms. No specific enzyme has been identified as the primary route of A77 1726, although its ability to inhibit CYP2C9, the P-450 isoenzyme responsible for the metabolism of many non-steroidal anti-inflammatory drugs (NSAIDs) suggests that CYP2C9 may be involved in the metabolism of A77 1726 [2]. CYP2C9 gene is polymorphic. Among Caucasian individuals there are two common allelic variants of the normal wild type allele (CYP2C9*1) named ∗
Corresponding author. Fax: +34-9-13305105. E-mail address: [email protected] (J.M. Ladero).
respectively CYP2C9*2 and CYP2C9*3, both being associated with impaired metabolism of CYP2C9 substrates [3,4]. Leflunomide is a relatively well tolerated drug. The commonest reported adverse events are diarrhoea, respiratory infections, nausea, headache, rash, dyspepsia and alopecia. Increased serum aminotransferase levels have been reported in 10% of treated patients, but only in less than half of these cases the final result was discontinuation of the treatment [1,5–9].
2. Case report A 67-year-old female, non alcohol-drinking, diagnosed of rheumatoid arthritis, was treated for at least 2 years with daily doses of enalapril (5 mg), prednisone (10 mg) and omeprazole (20 mg), weekly alendronate, calcium and Vitamin D supplements, acetaminophen as analgesic, and oral methotrexate (12.5 mg/weekly, total cumulative dose 1200 mg). She was not taking NSAIDs. Serum aminotransferases and gammaglutamyltransferase were controlled every 2 months, always with normal results. Thirty days before admission the clinical response was considered inadequate and methotrexate was withdrawn, starting leflunomide therapy at a dose of 20 mg/day and sodium aurothiomalate at
1590-8658/$30 © 2003 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dld.2003.06.002
C. Sevilla-Mantilla et al. / Digestive and Liver Disease 36 (2004) 82–84
weekly intervals (she received three doses totalling 75 mg of gold). Fifteen days after the onset of leflunomide therapy she developed diarrhoea and the drug was withdrawn. Diarrhoea did not subside and finally the patient was referred to our hospital. On physical examination the sclerae were mildly icteric, with no other liver-related signs. Blood counts were normal, as were ESR (19 mm/h), the pattern of serum protein electrophoresis and the levels of IgM, IgG and IgA. Total serum protein was 5.9 g/dl, with serum albumin 3.0 g/dl. A test for antinuclear antibodies was positive at 1:80; anti HBs, anti HBc, anti HCV and autoantibodies against smooth muscle, liver–kidney microsomes and mitochondria antigens were negative. Serologic tests for Ebstein–Barr virus, citomegalovirus and HIV were not available. Plasma levels of copper, ceruloplasmin, ferritin, alpha-1-antitrypsin, cholesterol, triglycerides and thyroid hormones were normal. Results of liver tests are shown in Table 1. The CYP2C9 genotype was determined in genomic DNA from the patient by the use of polymerase chain reaction (PCR) and restriction mapping as described elsewhere [3]. She was homozygous for the mutated CYP2C9*3 allele. A liver biopsy was performed 44 days after starting leflunomide. (Fig. 1). Liver structure is preserved with no fibrosis, portal tracts show mild mononuclear inflammatory infiltrate. Bile ductules were preserved. There is acidophilic change, with a few scattered apoptotic bodies, and focal lymphocytic infiltrate in zone 3, near the terminal venule, but not confluent necrosis. Clumps of Kupffer cells contain PAS-positive material. In some acini, reticulin framework is condensed near the terminal venules, but not in the vicinity of portal tracts. These changes are diagnostic of acute hepatitis and consistent with primary liver-cell damage. The patients was treated with cholestyramine, a drug known to interfere with the entero-hepatic cycle of leflunomide, and carried a favourable course, with clinical and biochemical normalisation at the Day 28 after admission (Table 1). She was discharged from the hospital and 3 months later the liver enzymes were normal.
3. Comments This case illustrates the development of acute hepatitis as a likely adverse event of leflunomide therapy. The liver dam-
83
age was preceded by diarrhoea, which is the most common adverse event associated with this drug, and was clinically mild but more serious from biochemical and histological viewpoints. Therefore, it seems advisable to control serum aminotransferase levels during the first 6 months of leflunomide therapy at monthly regular intervals. The great majority of liver-related adverse events appear during this period [7]. We have applied the RUCAM-CIOMS [10] scale for casualty assessment, taking in consideration the previous (methotrexate, acetaminophen, omeprazole, alendronate) and simultaneous (sodium aurothiomalate) use of other potentially hepatotoxic drugs and the unavailability of serologic tests for EBV, CMV and HIV (see above). The obtained score (seven points) establishes that the causal relation of leflunomide with the liver disease in this patient should be considered as probable. We know one case report of severe liver toxicity due to the association of leflunomide and methotrexate [11]. Our patient had taken methotrexate for 2 years, but this drug had been well tolerated and it was withdrawn just before the onset of leflunomide therapy; moreover, the liver damage induced by methotrexate is rarely an acute hepatitis, as in this case, but a chronic, biochemically silent, hepatic fibrosis [12]. The association of leflunomide and itraconazole resulted in a fatal hepatitis [13]. Our patient was treated simultaneously with leflunomide and sodium aurothiomalate. Gold salts have been involved in reactions of hepatotoxicity; nevertheless, these reactions are usually cholestatic in nature [14]. There are few published reports on leflunomide-induced liver damage. A letter of the manufacturer informs about 129 cases of serious liver damage over a total drug exposure of 104,000 patient–years. Most of these patients had comorbidities or received other hepatotoxic drugs. Ten deaths were possibly related to leflunomide. Only a few biopsies were performed, which showed a variety of abnormalities, including centrilobular necrosis with portal or periportal inflammation, steatosis, focal piecemeal necrosis and periportal fibrosis. Full information on this report is available on line [15]. The most relevant finding in our case was lobular inflammation; portal spaces were unaffected and there was no fibrosis. This patient carried a mutated CYP2C9 genotype (CYP2C9*3 in homozygosity) that determines the lowest
Table 1 Evolution of the liver biochemical abnormalities Parameter
ALT (U/l) AST (U/l) Alkaline phosphatase (U/l) Gammaglutamyltransferase (U/l) Bilirubin (mg/dl) a
Day since the admissiona Day 1
Day 5
Day 8
Day 13
Day 28
Day 70
462 249 602 244 2.8
550 290 777 386 3.5
517 264 765 377 2.7
270 104 673 282 1.4
26 43 390 99 –
14 17 175 – 0.6
Thirty days from starting leflunomide therapy and 15 since the onset of diarrhoea and the whithdrawal of leflunomide.
84
C. Sevilla-Mantilla et al. / Digestive and Liver Disease 36 (2004) 82–84
Fig. 1. There is patchy liver-cell drop-out and lymphocytic infiltration. An apoptotic body is seen (arrow).
metabolic rate for CYP2C9 substrates [4]. This genotype is extremely rare, as it is present in less than 1% of Caucasian individuals [3,16]. This finding may be coincidental, but if the CYP2C9 enzyme is involved in A77 1726 metabolism, as it is suggested by the blocking action of A77 1726 on CYP2C9 activity [2], it may be speculated that a poor metabolizer CYP2C9 status could increase the synthesis of some other toxic metabolite(s) of A77 1726 through alternative enzymatic pathways which at present are not known. In this regard it would be advisable to determine the CYP2C9 genotype of patients with side effects secondary to leflunomide, in order to obtain further confirmation for a putative association between mutated CYP2C9 genotypes and leflunomide-induced severe adverse effects. Conflict of interest statement None declared.
References
[5] [6] [7]
[8]
[9]
[10] [11]
[12] [13]
[1] Prakash A, Jarvis B. Leflunomide: a review of its use in active rheumatoid arthritis. Drugs 1999;58:1137–64. [2] Leflunomide (HWA486): investigator’s brochure. Wiesbaden, Germany: Hoechstmarion Roussel; 1998. p. 4-2–4-6. [3] Sullivan-Klose TH, Ghanayem BI, Bell DA, Zhang ZY, Kaminsky LS, Shenfield GM, et al. The role of the CYP2C9-Leu359 allelic variant in the tolbutamide polymorphism. Pharmacogenetics 1996;6: 341–9. [4] Haining RL, Hunter AP, Veronese M, Trager WF, Rettie AE. Allelic variants of the human cytochrome P450 2C9: baculovirus-mediated expression, purification, structural characterisation, substrate stere-
[14]
[15]
[16]
oselectivity, and prochiral selectivity of the wild-type and I359L mutated forms. Arch Biochem Biophys 1996;333:447–58. Rozman B. Clinical pharmacokinetics of leflunomide. Clin Pharmacokinet 2002;41:421–30. Smolen JS, Emery P. Efficacy and safety of leflunomide in active rheumatoid arthritis. Rheumatology 2000;39:48–56. Scott DL, Smolen JS, Kalden JR, van de Putte LB, Larsen A, Kvien TK, et al. Treatment of active rheumatoid arthritis with leflunomide: 2-year follow up of a double blind, placebo controlled trial versus sulfasalazine. Ann Rheum Dis 2001;60:913–23. Strand V, Cohen S, Schiff M, Weaver A, Flischmann R, Cannon G, et al. Treatment of active rheumatoid arthritis with leflunomide compared with placebo and methotrexate. Leflunomide rheumatoid arthritis investigators group. Arch Intern Med 1999;159:2542–50. Emery P, Breedveld FC, Lemmel EM, Kaltawasser JP, Dawes PT, Gomor B, et al. A comparison of the efficacy and safety of leflunomide and methotrexate for the treatment of rheumatoid arthritis. Rheumatology 2000;39:655–65. Larrey D. Epidemiology and individual susceptibility to adverse drug reactions affecting the liver. Sem Liver Dis 2002;22:145–55. Weinblatt ME, Dixon JA, Falchuk KR. Serious liver disease in a patient receiving methotrexate and leflunomide. Arthritis Rheum 2000;43:2609–11. Whiting-O’Keefe QE, Fye KH, Sack KD. Methotrexate and histologic hepatic abnormalities: a meta-analysis. Am J Med 1991;90:711–6. Legras A, Bergemer-Fouquet A-M, Jonville-Bera A-P. Fatal hepatitis with leflunomide and itraconazole. Am J Med 2002;113:352–3. González JA, Calvo J, Herrera A, Hortelano E, Folgado J, López MD. Hepatopat´ıa mixta por sales de oro v´ıa patenteral. Ann Med Interne 1990;7:477–9. Matteson E, Cush JJ. Reports of leflunomide hepatotoxicity in patients with rheumatoid arthritis. Hotline of the American College of Rheumatology. http:/www.rheumatology.org/research/hotline/ 0801leflunomide.html. Garc´ıa-Mart´ın E, Mart´ınez C, Ladero JM, Gamito FJ, Agúndez JAG. High frequency of mutations related to impaired CYP2C9 metabolism in a Caucasian population. Eur J Clin Pharmacol 2001;57:47–9.
Brief Clinical Observation
Leflunomide-induced acute hepatitis C. Sevilla-Mantilla a , L. Ortega b , J.A.G. Agúndez c , B. Fernández-Gutiérrez d , J.M. Ladero a,∗ , M. D´ıaz-Rubio a a
Service of Gastroenterology, Hospital Cl´ınico San Carlos, Complutense University, Ciudad Universitaria, Madrid 28040, Spain b Service of Pathology, Hospital Cl´ınico San Carlos, Complutense University, Madrid, Spain c Department of Pharmacology, University of Extremadura, Badajoz, Spain d Service of Rheumatology, Hospital Cl´ınico San Carlos, Complutense University, Madrid, Spain Received 7 April 2003; accepted 16 June 2003
Abstract Leflunomide, a new immunomodulatory agent, was prescribed to a 67-year-old female patient with rheumatoid arthritis. Fifteen days later she developed diarrhoea and elevated liver enzymes. A liver biopsy showed a pattern of acute hepatitis. The patient was homozygous for the rare CYP2C9*3 allele, which determines the slowest metabolic rate for CYP2C9 enzymatic activity, that is probably involved in the metabolism of leflunomide. Liver damage subsided in few weeks. This case illustrates the risk of hepatotoxicity by leflunomide and suggests that it is possibly related to CYP2C9 polymorphism. © 2003 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved. Keywords: CYP2C9; Genetic polymorphism; Leflunomide
1. Introduction Leflunomide is a new immunomodulatory agent that inhibits the enzyme dihydroorotate dehydrogenase, responsible for the de novo synthesis of pyrimidine-containing ribonucleotides. Activated T lymphocytes are especially sensitive to the effect of the drug [1]. Leflunomide has been approved for the treatment of rheumatoid arthritis and it is available in many countries as 20 mg tablets. Leflunomide is a prodrug that is almost completely converted into its active metabolite, A77 1726, through firstpass metabolism in the gut wall and the liver. Such activation seems to be mediated by several enzymatic and nonenzymatic mechanisms. No specific enzyme has been identified as the primary route of A77 1726, although its ability to inhibit CYP2C9, the P-450 isoenzyme responsible for the metabolism of many non-steroidal anti-inflammatory drugs (NSAIDs) suggests that CYP2C9 may be involved in the metabolism of A77 1726 [2]. CYP2C9 gene is polymorphic. Among Caucasian individuals there are two common allelic variants of the normal wild type allele (CYP2C9*1) named ∗
Corresponding author. Fax: +34-9-13305105. E-mail address: [email protected] (J.M. Ladero).
respectively CYP2C9*2 and CYP2C9*3, both being associated with impaired metabolism of CYP2C9 substrates [3,4]. Leflunomide is a relatively well tolerated drug. The commonest reported adverse events are diarrhoea, respiratory infections, nausea, headache, rash, dyspepsia and alopecia. Increased serum aminotransferase levels have been reported in 10% of treated patients, but only in less than half of these cases the final result was discontinuation of the treatment [1,5–9].
2. Case report A 67-year-old female, non alcohol-drinking, diagnosed of rheumatoid arthritis, was treated for at least 2 years with daily doses of enalapril (5 mg), prednisone (10 mg) and omeprazole (20 mg), weekly alendronate, calcium and Vitamin D supplements, acetaminophen as analgesic, and oral methotrexate (12.5 mg/weekly, total cumulative dose 1200 mg). She was not taking NSAIDs. Serum aminotransferases and gammaglutamyltransferase were controlled every 2 months, always with normal results. Thirty days before admission the clinical response was considered inadequate and methotrexate was withdrawn, starting leflunomide therapy at a dose of 20 mg/day and sodium aurothiomalate at
1590-8658/$30 © 2003 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.dld.2003.06.002
C. Sevilla-Mantilla et al. / Digestive and Liver Disease 36 (2004) 82–84
weekly intervals (she received three doses totalling 75 mg of gold). Fifteen days after the onset of leflunomide therapy she developed diarrhoea and the drug was withdrawn. Diarrhoea did not subside and finally the patient was referred to our hospital. On physical examination the sclerae were mildly icteric, with no other liver-related signs. Blood counts were normal, as were ESR (19 mm/h), the pattern of serum protein electrophoresis and the levels of IgM, IgG and IgA. Total serum protein was 5.9 g/dl, with serum albumin 3.0 g/dl. A test for antinuclear antibodies was positive at 1:80; anti HBs, anti HBc, anti HCV and autoantibodies against smooth muscle, liver–kidney microsomes and mitochondria antigens were negative. Serologic tests for Ebstein–Barr virus, citomegalovirus and HIV were not available. Plasma levels of copper, ceruloplasmin, ferritin, alpha-1-antitrypsin, cholesterol, triglycerides and thyroid hormones were normal. Results of liver tests are shown in Table 1. The CYP2C9 genotype was determined in genomic DNA from the patient by the use of polymerase chain reaction (PCR) and restriction mapping as described elsewhere [3]. She was homozygous for the mutated CYP2C9*3 allele. A liver biopsy was performed 44 days after starting leflunomide. (Fig. 1). Liver structure is preserved with no fibrosis, portal tracts show mild mononuclear inflammatory infiltrate. Bile ductules were preserved. There is acidophilic change, with a few scattered apoptotic bodies, and focal lymphocytic infiltrate in zone 3, near the terminal venule, but not confluent necrosis. Clumps of Kupffer cells contain PAS-positive material. In some acini, reticulin framework is condensed near the terminal venules, but not in the vicinity of portal tracts. These changes are diagnostic of acute hepatitis and consistent with primary liver-cell damage. The patients was treated with cholestyramine, a drug known to interfere with the entero-hepatic cycle of leflunomide, and carried a favourable course, with clinical and biochemical normalisation at the Day 28 after admission (Table 1). She was discharged from the hospital and 3 months later the liver enzymes were normal.
3. Comments This case illustrates the development of acute hepatitis as a likely adverse event of leflunomide therapy. The liver dam-
83
age was preceded by diarrhoea, which is the most common adverse event associated with this drug, and was clinically mild but more serious from biochemical and histological viewpoints. Therefore, it seems advisable to control serum aminotransferase levels during the first 6 months of leflunomide therapy at monthly regular intervals. The great majority of liver-related adverse events appear during this period [7]. We have applied the RUCAM-CIOMS [10] scale for casualty assessment, taking in consideration the previous (methotrexate, acetaminophen, omeprazole, alendronate) and simultaneous (sodium aurothiomalate) use of other potentially hepatotoxic drugs and the unavailability of serologic tests for EBV, CMV and HIV (see above). The obtained score (seven points) establishes that the causal relation of leflunomide with the liver disease in this patient should be considered as probable. We know one case report of severe liver toxicity due to the association of leflunomide and methotrexate [11]. Our patient had taken methotrexate for 2 years, but this drug had been well tolerated and it was withdrawn just before the onset of leflunomide therapy; moreover, the liver damage induced by methotrexate is rarely an acute hepatitis, as in this case, but a chronic, biochemically silent, hepatic fibrosis [12]. The association of leflunomide and itraconazole resulted in a fatal hepatitis [13]. Our patient was treated simultaneously with leflunomide and sodium aurothiomalate. Gold salts have been involved in reactions of hepatotoxicity; nevertheless, these reactions are usually cholestatic in nature [14]. There are few published reports on leflunomide-induced liver damage. A letter of the manufacturer informs about 129 cases of serious liver damage over a total drug exposure of 104,000 patient–years. Most of these patients had comorbidities or received other hepatotoxic drugs. Ten deaths were possibly related to leflunomide. Only a few biopsies were performed, which showed a variety of abnormalities, including centrilobular necrosis with portal or periportal inflammation, steatosis, focal piecemeal necrosis and periportal fibrosis. Full information on this report is available on line [15]. The most relevant finding in our case was lobular inflammation; portal spaces were unaffected and there was no fibrosis. This patient carried a mutated CYP2C9 genotype (CYP2C9*3 in homozygosity) that determines the lowest
Table 1 Evolution of the liver biochemical abnormalities Parameter
ALT (U/l) AST (U/l) Alkaline phosphatase (U/l) Gammaglutamyltransferase (U/l) Bilirubin (mg/dl) a
Day since the admissiona Day 1
Day 5
Day 8
Day 13
Day 28
Day 70
462 249 602 244 2.8
550 290 777 386 3.5
517 264 765 377 2.7
270 104 673 282 1.4
26 43 390 99 –
14 17 175 – 0.6
Thirty days from starting leflunomide therapy and 15 since the onset of diarrhoea and the whithdrawal of leflunomide.
84
C. Sevilla-Mantilla et al. / Digestive and Liver Disease 36 (2004) 82–84
Fig. 1. There is patchy liver-cell drop-out and lymphocytic infiltration. An apoptotic body is seen (arrow).
metabolic rate for CYP2C9 substrates [4]. This genotype is extremely rare, as it is present in less than 1% of Caucasian individuals [3,16]. This finding may be coincidental, but if the CYP2C9 enzyme is involved in A77 1726 metabolism, as it is suggested by the blocking action of A77 1726 on CYP2C9 activity [2], it may be speculated that a poor metabolizer CYP2C9 status could increase the synthesis of some other toxic metabolite(s) of A77 1726 through alternative enzymatic pathways which at present are not known. In this regard it would be advisable to determine the CYP2C9 genotype of patients with side effects secondary to leflunomide, in order to obtain further confirmation for a putative association between mutated CYP2C9 genotypes and leflunomide-induced severe adverse effects. Conflict of interest statement None declared.
References
[5] [6] [7]
[8]
[9]
[10] [11]
[12] [13]
[1] Prakash A, Jarvis B. Leflunomide: a review of its use in active rheumatoid arthritis. Drugs 1999;58:1137–64. [2] Leflunomide (HWA486): investigator’s brochure. Wiesbaden, Germany: Hoechstmarion Roussel; 1998. p. 4-2–4-6. [3] Sullivan-Klose TH, Ghanayem BI, Bell DA, Zhang ZY, Kaminsky LS, Shenfield GM, et al. The role of the CYP2C9-Leu359 allelic variant in the tolbutamide polymorphism. Pharmacogenetics 1996;6: 341–9. [4] Haining RL, Hunter AP, Veronese M, Trager WF, Rettie AE. Allelic variants of the human cytochrome P450 2C9: baculovirus-mediated expression, purification, structural characterisation, substrate stere-
[14]
[15]
[16]
oselectivity, and prochiral selectivity of the wild-type and I359L mutated forms. Arch Biochem Biophys 1996;333:447–58. Rozman B. Clinical pharmacokinetics of leflunomide. Clin Pharmacokinet 2002;41:421–30. Smolen JS, Emery P. Efficacy and safety of leflunomide in active rheumatoid arthritis. Rheumatology 2000;39:48–56. Scott DL, Smolen JS, Kalden JR, van de Putte LB, Larsen A, Kvien TK, et al. Treatment of active rheumatoid arthritis with leflunomide: 2-year follow up of a double blind, placebo controlled trial versus sulfasalazine. Ann Rheum Dis 2001;60:913–23. Strand V, Cohen S, Schiff M, Weaver A, Flischmann R, Cannon G, et al. Treatment of active rheumatoid arthritis with leflunomide compared with placebo and methotrexate. Leflunomide rheumatoid arthritis investigators group. Arch Intern Med 1999;159:2542–50. Emery P, Breedveld FC, Lemmel EM, Kaltawasser JP, Dawes PT, Gomor B, et al. A comparison of the efficacy and safety of leflunomide and methotrexate for the treatment of rheumatoid arthritis. Rheumatology 2000;39:655–65. Larrey D. Epidemiology and individual susceptibility to adverse drug reactions affecting the liver. Sem Liver Dis 2002;22:145–55. Weinblatt ME, Dixon JA, Falchuk KR. Serious liver disease in a patient receiving methotrexate and leflunomide. Arthritis Rheum 2000;43:2609–11. Whiting-O’Keefe QE, Fye KH, Sack KD. Methotrexate and histologic hepatic abnormalities: a meta-analysis. Am J Med 1991;90:711–6. Legras A, Bergemer-Fouquet A-M, Jonville-Bera A-P. Fatal hepatitis with leflunomide and itraconazole. Am J Med 2002;113:352–3. González JA, Calvo J, Herrera A, Hortelano E, Folgado J, López MD. Hepatopat´ıa mixta por sales de oro v´ıa patenteral. Ann Med Interne 1990;7:477–9. Matteson E, Cush JJ. Reports of leflunomide hepatotoxicity in patients with rheumatoid arthritis. Hotline of the American College of Rheumatology. http:/www.rheumatology.org/research/hotline/ 0801leflunomide.html. Garc´ıa-Mart´ın E, Mart´ınez C, Ladero JM, Gamito FJ, Agúndez JAG. High frequency of mutations related to impaired CYP2C9 metabolism in a Caucasian population. Eur J Clin Pharmacol 2001;57:47–9.