What is leflunomide, and how does it work (mechanism of action)?
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.
What brand names are available for leflunomide?
Arava
Is leflunomide available as a generic drug?
No
Do I need a prescription for leflunomide?
Yes
What are the side effects of leflunomide?
The most frequently reported side effects are:
Other important side effects of leflunomide include:
- 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 fatal liver failure. More often it
causes 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.
QUESTION
The term arthritis refers to stiffness in the joints.
See Answer
What is the dosage for leflunomide?
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.
Which drugs or supplements interact with leflunomide?
Cholestyramine
(Questran, Questran Light) 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. Increased
activity of warfarin
(Coumadin) by leflunomide has been reported rarely. Leflunomide also
may increase the blood concentration of tolbutamide.
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Is leflunomide safe to take if I’m pregnant or breastfeeding?
Leflunomide is harmful to the developing fetus and should
not be used during pregnancy.
It is unknown whether leflunomide accumulates in breast milk. Since leflunomide could cause harm to the infant, women taking
leflunomide probably should refrain from
breastfeeding.
What else should I know about leflunomide?
What preparations of leflunomide are available?
10 and 20 mg tablets
How should I keep leflunomide stored?
Leflunomide should be stored at room temperature 15 C – 30 C (59 F – 86 F).