DRUG CLASS AND MECHANISM: Leflunomide is an oral, disease-modifying drug that is used in the treatment of rheumatoid arthritis. Leflunomide reduces inflammation in the joints that is responsible for both the symptoms of rheumatoid arthritis and the destruction of joints. This reduces symptoms as well as the progressive deformities of the joints caused by the arthritis. Leflunomide reduces inflammation by suppressing the activity of immune cells responsible for the inflammation. Leflunomide suppresses immune cells by inhibiting dihydroorotate dehydrogenase, an enzyme that is necessary for the production of DNA and RNA. Without DNA and RNA the immune cells (and most other types of cells) cannot multiply or function (or exist). Because of its unique and different mechanism of action, leflunomide is of value when added to other medications used for treating rheumatoid arthritis. Leflunomide was approved by the FDA in September, 1998.

PREPARATIONS: 10, 20, and 100 mg tablets

STORAGE: Leflunomide should be stored at room temperature 15-30°C (59-86°F).

PRESCRIBED FOR: Leflunomide is used for the treatment of active rheumatoid arthritis in adults. It reduces the signs, symptoms and joint damage caused by rheumatoid arthritis.

DOSING: The usual dose is 100 mg daily for the first 3 days, followed by 20 mg daily. Doctors may reduce the dose to 10 mg daily if side effects appear. It may require up to four weeks of therapy before improvement of the arthritis are seen. It is not known if ingestion of food or alcohol affects the absorption or action of leflunomide.

DRUG INTERACTIONS: Cholestyramine and charcoal decrease the concentration of the active form of leflunomide in the blood probably by preventing absorption. Rifampin increases the blood concentration of the active form of leflunomide by 40% probably by increasing the conversion of leflunomide to its active form. This may increase the side effects of leflunomide.

PREGNANCY: Leflunomide is harmful to the developing fetus and should not be used during pregnancy.

NURSING MOTHERS: It is unknown whether leflunomide accumulates in breast milk. Since leflunomide could cause harm to the infant, women taking leflunomide should probably refrain from breastfeeding.

SIDE EFFECTS: The most frequently reported side effects are diarrhea, nausea, headache, rash, itching, loss or thinning of hair and weight loss. Leflunomide also may cause high blood pressure, chest pain and abnormal heartbeats. Since leflunomide suppresses the immune system, it may increase the risk to patients of infections. The most frequently reported infections involve the respiratory tract. Leflunomide may cause abnormal liver tests in the blood, suggesting damage to the liver. The liver tests usually return to normal with continued treatment. The dose of leflunomide should be reduced if liver tests are persistently greater than twice the upper limit of normal, and leflunomide should be discontinued if the levels remain above three times the upper limit of normal despite a reduction in dose. Leflunomide should not be administered to individuals with liver problems.

Caution! Before starting to take this medicine, it is vital that you should consult your doctor! Do not use it on your own initiative, without medical advice.