How Arava Works

Arava works by suppressing the immune system. It inhibits an enzyme called dihydroorotate dehydrogenase (DHODH). This enzyme is associated with a number of functions in the body including the synthesis, or creation, of pyrimidines. This effect makes Arava a member of a class of medications called pyrimidine synthesis inhibitors.

Some of the most important building blocks of DNA and RNA that encode genetic information are derived from pyrimidines: cytosine (C) found in both DNA and RNA; thymine (T) found in DNA, and uracil (U) found in RNA.

The exact mechanisms of how Arava suppresses the immune system is not fully understood. Many researchers think that Arava suppresses the immune system by depleting the pyrimidine supply used by T-cells (a type of white blood cell in the immune system). It is thought that T-cells need a good supply of pyrimidines to divide and rapidly create more copies of themselves. Researchers also suspect that other more complex cellular signalling pathways might be involved too. More research will help to better understand how the immune system becomes suppressed in those who take Arava.

In many types of arthritis, the immune system is not functioning correctly and attacks the body by mistake. In suppressing the immune system, Arava helps stop this attack.

In people with arthritis, this medicine can help reduce pain and swelling (inflammation) in the joints, improve day to day function, and prevent long-term damage caused by joint inflammation.

The suppression of the immune system can also make it a bit harder for the body to fight infections, so people taking Arava should report any fevers or infections to their doctor.

Side Effects of Arava

The most common side effect of Arava is nausea and diarrhea.

Monthly blood tests are important to ensure that Arava does not harm the liver or blood counts. Patients should stop drinking alcohol to reduce the chances of liver side effects.

Arava may cause birth defects and result in miscarriage. Anyone who becomes pregnant while taking this medicine should notify a doctor immediately. Patients considering pregnancy should consider using a different medication because Arava can stay in the body for up to two years.

MORE COMMON side-effects include:

  • Nausea and diarrhea
  • Skin rash
  • Hair thinning or loss which is reversible when the medication is stopped

RARE side-effects include:

  • Blood pressure – Arava can rarely cause an increase in blood pressure. Patients starting Arava should tell their doctor if they have high blood pressure.
  • Liver – Arava may irritate the liver. This does not usually cause symptoms but may be found on blood tests. Liver side effects are rare and are usually reversible when caught early through regular monthly blood tests.
  • Bone Marrow – Arava can cause a drop in the numbers of white blood cells (which help fight infection) and platelets (which help to stop bleeding). With monthly blood tests, it is unusual for this to be a serious problem.
  • Infection – Any infections or fevers should be taken seriously and reviewed by a doctor.
  • Tingling in the Hands and Feet – Arava can rarely cause “pins and needles” or tingling in the hands and feet.
  • Trouble breathing – Arava can very rarely cause an allergic reaction in the lungs. Patients should call a doctor if they develop a cough that won’t go away, or develop shortness of breath.

How to minimize the side-effects of Arava:

  • Patients should get regular blood tests as requested by their doctor (usually monthly for Arava) to monitor for side effects, and remember to attend their appointments
  • In cases where side effects are a problem, reducing the dose or taking the medicine every other day can often help reduce them. This should only be done with guidance from a doctor.

Who Should NOT Take Arava

Patients who should NOT be taking Arava (Leflunomide) include:

  • Patients who have had a previous serious reaction to Arava.
  • Women who are pregnant, planning on becoming pregnant, or currently breast feeding.
  • Men who are planning pregnancy with their partner.
  • Patients with diseases of the liver, kidney, or blood disorders.
  • Patients with active infections.

Patients who are about to have surgery should discuss stopping Arava with their doctor. Patients who become pregnant while taking Arava should notify their doctor immediately.

When to Call a Doctor

Patients should call their doctor if they feel sick and want to stop, or they are concerned about any side effects.

Other reasons to call a doctor while taking Arava include:

  • Diarrhea
  • Severe weight loss
  • Shortness of breath
  • Developing a rash
  • Becoming pregnant or planning pregnancy
  • Before having surgery

Arava Video

Watch Dr. Andy Thompson, a Canadian rheumatologist, introduce Arava.