Journal of Postgraduate Medicine
 Open access journal indexed with Index Medicus & EMBASE  
     Home | Subscribe | Feedback  

[Download PDF
Year : 2004  |  Volume : 50  |  Issue : 2  |  Page : 154-157  

Leflunomide: A novel disease modifying anti-rheumatic drug

Vijay P Kale, LS Bichile 
 Department of Medicine and Rheumatology Services, Seth G. S. Medical College and K. E. M. Hospital, Parel, Mumbai - 400012, India

Correspondence Address:
Vijay P Kale
Department of Medicine and Rheumatology Services, Seth G. S. Medical College and K. E. M. Hospital, Parel, Mumbai - 400012

How to cite this article:
Kale VP, Bichile L S. Leflunomide: A novel disease modifying anti-rheumatic drug.J Postgrad Med 2004;50:154-157

How to cite this URL:
Kale VP, Bichile L S. Leflunomide: A novel disease modifying anti-rheumatic drug. J Postgrad Med [serial online] 2004 [cited 2023 May 30 ];50:154-157
Available from:

Full Text

Rheumatoid arthritis (RA) is the most common form of inflammatory arthritis affecting approximately 0.5 to 1% of the population. It follows a progressive course with evidence of structural joint damage occurring as early as 4 weeks after the onset of symptoms and usually gets fully established by 2 years in untreated patients.[1] Based on this observation, current treatment guidelines emphasize the early use of disease-modifying anti-rheumatic drugs (DMARDs), a class of therapeutic agents that have the potential to minimize or prevent joint damage.[2] However, most of the current DMARDs show loss of efficacy with time and/or development of serious adverse effects. There is therefore a need for newer DMARDs with better efficacy and a better safety profile. Leflunomide (active metabolite A77 1726) is one such new drug with novel immunomodulatory and anti-inflammatory properties that has shown promising results in terms of efficacy and safety for the treatment of this crippling autoimmune disease and is a welcome addition to the roster of anti-rheumatoid drugs.

 Chemical structure

Leflunomide, an isoxazole derivative, is a prodrug that is rapidly and almost completely metabolised after absorption to its active metabolite A77 1726 (open ring metabolite- malononitrilamide).[3]

The overall reaction involves the opening of the five-membered ring, forming cyanide and a hydroxyl group. This occurs quickly in the gut walls and liver.

 Mechanism of Action

A77 1726 has several mechanisms of action as listed below-

1) Primary immunomodulating action - Inhibition of de novo pyrimidine synthesis. [3], [4]

Activated lymphocytes in RA require an eightfold increase in their levels of ribonucleotide uridine monophosphate (rUMP) and other pyrimidine ribonucleotides in order to progress from G1 to the S phase of the cell cycle for proliferation and they must use de novo synthesis of pyrimidines. A77 1726 acts reversibly on the critical mitochondrial rate-limiting enzyme dihydroorate dehydrogenase (DHODH) required for the de novo synthesis of rUMP. Inhibition of this enzyme leads to decreased rUMP, decreased DNA and RNA synthesis, inhibition of T cell proliferation and G1 cell cycle arrest. T cell-dependent B cell formation of autoantibodies, including IgA and IgG isotypes, is also inhibited by A77 1726.[5]

2) Anti-inflammatory actions-

A77 1726 inhibits the activation and gene expression of nuclear factor (NF) kB required for the activation of genes for various inflammatory cytokines and metallo-proteinases.[6]

A77 1726 increases the production of immunosuppressive transforming growth factor-b1 protein (TGF-b1) and inhibits theh production of pro-inflammatory cytokines TNF-a and interleukin 1b.[4]



After oral administration leflunomide is rapidly metabolised to its major active form A77 1726 in the gut wall, plasma and in the liver. The parent compound is rarely detected in the plasma. Peak plasma levels of A77 1726 are reached 6-12 h after oral administration of leflunomide. Bioavailability of A77 1726 is unaffected by high fat meal. It has a low volume of distribution as it is >99% protein-bound. A77 1726 undergoes entero-hepatic circulation and biliary recycling may contribute to its long elimination half-life (~ 2 weeks). A77 1726 is further metabolised and excreted in the urine as an oxalinic acid derivative and in the unchanged form in faeces.

 Drug interactions

There is limited data regarding drug interactions with leflunomide. In vivo drug interaction studies have demonstrated a lack of a significant drug interaction between leflunomide and methotrexate.[8],[16] Levels of leflunomide are increased after multiple dosing with rifampin.[8] A77 1726 inhibits CYP2C9 that metabolises many NSAIDS. However, no clinically relevant interactions were observed in clinical trials in patients receiving leflunomide with NSAIDS, which are so frequently used in RA treatment.[8] No interactions have been documented with oral contraceptives that were used by several subjects in the clinical trials.

 Comparison of Efficacy, Safety and Tolerability with established DMARDs

The clinical efficacy and slowing of radiological progression in active RA with leflunomide monotherapy as compared to placebo, methotrexate (MTX) and sulphasalazine (SSZ) has been evaluated in 6 large, double-blind, randomised controlled trials. A brief overview of these trials and the outcomes measured are shown in the [table].

A systematic review and meta-analysis of the above 6 trials by Oshir et al[15] concludes that

Comparison with Placebo: The pooled estimates of the clinical efficacy of leflunomide shows it to be significantly better than placebo at 6 and 12 months in all the clinical outcomes. Progression of radiological changes was also significantly slower in the leflunomide-treated group than the placebo group. Adverse events in the leflunomide-treated group that were significantly increased as compared to placebo and included alopecia, gastrointestinal symptoms and elevated liver function tests.

Efficacy and safety in combination with MTX

A recent randomised, double-blind, placebo-controlled trial by Kremer et al,[16] showed statistically significant efficacy in the ACR20 response rate and functional disability when compared with the placebo-MTX combination for patients with active RA despite stable doses of MTX. The combination of the two anti-metabolites was well tolerated and can be used safely with appropriate liver enzyme and haematological monitoring. No significant differences in the adverse effects were seen when compared with the placebo-MTX group.

Long-term efficacy and safety of leflunomide

A 5-year open-labelled, non-controlled extension study by Kalden et al,[17] demonstrated that the early efficacy of leflunomide [ACR20, ACR50, ACR70 response rates and health assessment questionnaire (HAQ) scores] seen at 1 year in patients with RA was maintained for up to 5 years. The long-term safety profile was no different from previous trials. No new adverse events were observed and liver functions were normal in the majority of patients throughout the study. The subjects included in this extension study were those who had completed full 24 months of leflunomide treatment in the previous 2 Phase III trials.[11],[13]

 Adverse Drug Effects

The major adverse events reported in the clinical trials included gastrointestinal symptoms (diarrhoea, dyspepsia, nausea, abdominal pain, oral ulcers), elevated liver function tests, skin rash/allergic reactions, alopecia, infections, weight loss and hypertension.[15] Only GI symptoms, alopecia, and hypertension were found to be significantly more in the leflunomide group as compared to MTX.[15] Adverse events were similar when comparing leflunomide and SSZ.[15] New onset hypertension as a side-effect of leflunomide therapy has been demonstrated in a prospective trial by Rozman et al,[18] highlighting the need for regular measurement of blood pressure during leflunomide treatment. A rise in the systolic blood pressure was noted after 4 weeks of initiating treatment with leflunomide. By contrast, the rise in diastolic pressure appeared later.

Less frequently seen adverse events[8] include urinary tract infections, respiratory tract infections and bronchitis, and minor musculoskeletal problems (backache, tenosynovitis, myalgias). There have been rare reports of sepsis, leukopenia, pancytopenia,[8] serious skin reactions (Stevens-Johnsons syndrome,[8] toxic epidermal necrolysis[8] and erythema multiforme-like drug eruption[19] and interstitial lung disease[8] in patients receiving leflunomide alone.

 Dosage and administration

Leflunomide therapy is initiated orally with a loading dose of 100 mg/day administered once daily for 3 days to hasten attainment of the steady state concentration (Css), and maintenance dose of 20 mg/day. If the dose of 20 mg/day is not well tolerated then the dosage is decreased to 10 mg/day. Dosages more than 20 mg/day are not recommended.

Recent open-labelled trials[20],[21] with weekly 100 mg Leflunomide showed the same efficacy and less toxicity than the conventional daily dosage of leflunomide. Another important benefit was a reduction in the monthly cost of Leflunomide treatment. These findings with a weekly dosage of leflunomide are encouraging but more comparative and blinded trials are required to confirm the same.


Patients taking leflunomide should have a complete haemogram and ALT (SGPT), monitored at baseline and monthly for 6 months following initiation of therapy, if stable every 6 to 8 weeks thereafter. In addition, if leflunomide and MTX are given concomitantly, American College of Rheumatology (ACR) guidelines for monitoring methotrexate-induced liver toxicity must be followed.


There is no data regarding the safety of leflunomide in children with JRA and it is not recommended for patients <18 yrs of age. It is contraindicated in those with hepatic insufficiency. Caution needs to be exercised in patients with chronic renal insufficiency as plasma levels of A77 1726 are increased with impaired kidney function.

 Reproductive Adverse effects


Leflunomide is contraindicated in pregnant females and those not on reliable contraception because of demonstrated teratogenic effects in mice. Although male-mediated fetotoxic effects are not known, men wishing to have a child should avoid the drug. Women/men on leflunomide and wanting to have a child should undergo drug elimination procedure and ensure non-detectable plasma levels (less than 0.02 mg/L or 0.02 g/mL).[8]

 Drug elimination procedure


If there are indications to stop the drug on account of adverse reactions, overdosage or reproductive issues, the following is undertaken to achieve non-detectable plasma levels (less than 0.02 mg/L or 0.02 g/mL)

1) Administer cholestyramine 8 g 3 times daily for 11 days. (The 11 days do not need to be consecutive unless there is a need to lower the plasma level rapidly.) Verify plasma levels less than 0.02 mg/L (0.02 g/mL) by two separate tests at least 14 days apart. If plasma levels are higher than 0.02 mg/L, additional cholestyramine treatment should be considered.

2) Administration of activated charcoal (powder made into a suspension) orally or via nasogastric tube (50 g every 6 hours for 24 hours) in addition to the above, if rapid lowering of the drug levels is indicated.

 Role of leflunomide in the management of rheumatoid arthritis

The efficacy and safety of leflunomide as monotherapy is comparable to that of first-line DMARDs-MTX and SSZ. However, rheumatologists have differing opinions regarding the exact place of leflunomide in the hierarchy of DMARDs for RA. Presently, leflunomide is considered for use in the following clinical situations -

1) As monotherapy in place of MTX or SSZ when the latter drugs are poorly tolerated or contraindicated.[22],[23]

2) Refractory RA patients- In combination (add-on therapy) with MTX for patients with persistent active RA despite recommended doses of MTX.[16],[22]

Further studies and longer follow-up periods are required before it can be advocated as first-line therapy for use in combination with other DMARDS.

 Constraints of Leflunomide therapy with respect to Indian patients

1) High cost of therapy as compared to established DMARDs.

2) Lack of facilities to monitor blood levels during drug elimination procedures when indicated.

 Other potential indications for Leflunomide

Leflunomide as an immunomodulator is presently being evaluated for use in patients with systemic lupus erythematosus,[24] Wegener's granulomatosis,[25] Crohn's disease,[26] and solid tumours.[27]


Leflunomide, a new DMARD with novel immunomodulatory and anti-inflammatory properties, has been added to the armamentarium against RA after more than 10 years of use of established DMARDs. It has shown equivalent efficacy, safety and tolerability when compared with the existing first-line DMARDs - SSZ and MTX- in controlled clinical trials. With extended experience in routine clinical practice, it may be a first choice when starting DMARD treatment for this progressive and disabling disease. There are also encouraging results with weekly leflunomide therapy which, if confirmed with large-scale blinded trials, may result in lesser cost of therapy, less side-effects and better compliance without loss of efficacy.


1Fuchs HA, Kaye JJ, Callahan LF, Nance EP, Pincus T. Evidence of significant radiographic damage in rheumatoid arthritis within the first 2 years of disease. J Rheumatol 1989;16:585-91.
2Guidelines for the management of rheumatoid arthritis. American College of Rheumatology Ad Hoc Committee on Clinical Guidelines. Arthritis Rheum 1996;39:713-22.
3Breedveld FC, Dayer JM. Leflunomide: mode of action in the treatment of rheumatoid arthritis. Ann Rheum Dis 2000;59:841-9
4Prakash A, Jarvis B. Leflunomide- A review of its use in active Rheumatoid arthritis. Drugs 1999;58:1137-64
5Siemasko KF, Chong ASF, Williams JW, Bremer EG, Finnegan A. Regulation of B cell function by the immunsuppressive agent leflunomide. Transplantation 1996;61:635-42
6Manna SK, Aggarwal BB. Immunosuppressive leflunomide metabolite (A77 1726) blocks TNF-dependent nuclear factor-kappa B activation and gene expression. J Immunol 1999;162:2095-102.
7Hamilton LC, Vojnovic I, Marner TD. A771726, the active metabolite of leflunomide, directly inhibits the activity of cyclo-oxygenase-2 in vitro and in vivo in a substrate-sensitive manner. Br J Pharmacol 1999;127:1589-96.
8Arava (Leflunomide) Prescribing Information as of September 2003. Aventis Pharmaceuticals Inc. Kansas City, MO 64137
9Mladenovic V, Domljan Z, Rozman B, Jajic I, Mihajlovic D, Dordevic J, et al. Safety and effectiveness of leflunomide in the treatment of patients with active rheumatoid arthritis. Arthritis Rheum 1995;38:1595-603.
10Strand V, Cohen S, Schiff M, Weaver A, Fleischmann R, Cannon G, et al. Treatment of active rheumatoid arthritis with leflunomide compared with placebo and methotrexate. Arch Intern Med 1999;159:2542-50.
11Emery P, Breedveld FC, Lemmel EM, Kaltwasser 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 (Oxford) 2000;39:655-65.
12Cohen S, Cannon GW, Schiff M, Weaver A, Fox R, Olsen N, et al. Two-year, blinded, randomised, controlled trial of treatment of rheumatoid arthritis with leflunomide compared with methotrexate. Arthritis Rheum 2001;44:1984-92.
13Smolen JS, Kalden JR, Scott DL, Rozman B, Kvien TK, Larsen A, et al. Efficacy and safety of leflunomide compared with placebo and sulphasalazine in active rheumatoid arthritis: a double-blind, randomised, multicentric trial. Lancet 1999;353:259-66.
14Scott DL, Smolen JS, Kalden JR, Van de Putte LB, Larsen A, Kvien TK, et al. Treatment of active rheumatoid arthritis with leflunomide: two year follow-up of a double-blind, placebo controlled trial versus sulphasalazine. Ann Rheum Dis 2001;60:913-23.
15Osiri M, Shea B, Robinson V, Suarez-Almazor M, Strand V, Tugwell P, et al. Leflunomide for the treatment of rheumatoid arthritis: A systematic review and meta-analysis. J Rheumatol 2003;30:1182-90.
16Kremer JM, Genovese MC, Cannon GW, Caldwell JR, Cush JJ, Furst DE, et al. Concomitant leflunomide therapy in patients with active rheumatoid arthritis despite stable doses of methotrexate. A randomized, double-blind, placebo-controlled trial. Ann Intern Med. 2002;137:726-33.
17Kalden JR, Schattenkirchner M, Sorensen H, Emery P, Deighton C, Rozman B, et al. The efficacy and safety of leflunomide in patients with active rheumatoid arthritis: a five-year follow-up study. Arthritis Rheum 2003;48:1513-20.
18Rozman B, Praprotnik D, Logar D, Tomsic M, Hojnik M, Kos-Golja M, et al. Leflunomide and hypertension. Ann Rheum Dis 2002;61:567-9.
19Fischer TW, Bauer HI, Graefe T, Barta U, Elsner P. Erythema multiforme-like drug eruption with oral involvement after intake of leflunomide. Dermatology 2003;207:386-9.
20Jakez-Ocampo, Richaud-Patin Y, Granados J, Sanchez-Guerrero J, Llorente L. Weekly leflunomide as monotherapy for recent-onset rheumatoid arthritis. Arthritis Rheum 2004;51:147-8.
21Jaimes-Hernandez J, Robles- San Roman M, Suarez-Otero R, Daval Zugasti ME, Arroyo-Borrego S. Rheumatoid arthritis treatment with weekly leflunomide: an open-label study. J Rheumatol 2004;31:235-7.
22Harris ED, Jr. Treatment of Rheumatoid arthritis. In: Ruddy S, Harris ED, Sledge CB, eds, Kelly's Textbook of Rheumatology. 6th ed, W B Saunders Company, 2000:p-1017.
23Breedveld FC. Is there a place for leflunomide in the treatment of rheumatoid arthritis? Lancet 2001;358:1198-200.
24Remer CF, Weisman MH, Wallace DJ. Benefits of leflunomide in systemic lupus erythematosus:a pilot observational study. Lupus 2001;10:480-3.
25Metzler C, Fink C, Lamprecht P, Gross WL, Reinhold-Keller E. Maintenance of remission with leflunomide in Wegener's granulomatosis. Rheumatology (Oxford) 2004;43:315-20.
26Prajapati DN, Knox JF, Emmons J, Saeian K, Csuka ME, Binion DG. Leflunomide treatment of Crohn's disease patients intolerant to standard immunomodulator therapy. J Clin Gastroenterol 2003;37:125-8.
27Eckhardt SG, Rizzo J, Sweeney KR, Cropp G, Baker SD, Kraynak MA, et al. Phase I and pharmacologic study of the tyrosine kinase inhibitor SU101 (Leflunomide) in patients with advanced solid tumours. Clin Oncol 1999;17:1095-104.

Tuesday, May 30, 2023
 Site Map | Home | Contact Us | Feedback | Copyright  and disclaimer