Liver Injury Warning for MS Drug Avonex
Rare Cases Reported in Avonex Users
March 16, 2005 -- Patients taking the multiple sclerosis (MS) drug Avonex
should be watched for possible liver problems, says the drug's maker.
Rare cases of severe liver injury, including cases of liver failure, have
been reported among Avonex users, says Avonex's maker, Biogen, in a letter to
"Patients should be monitored for signs of [liver] injury," says the
revised Avonex warning label.
Here's how the drug's web site puts it:
"Your liver may be affected by taking Avonex and a few patients have
developed severe liver injury. Your healthcare provider may ask you to have
regular blood tests to make sure that your liver is working properly. If your
skin or the whites of your eyes become yellow or if you are bruising easily you
should call your doctor immediately."
Liver Damage Without Symptoms
Liver enzymes can become elevated while taking Avonex. This elevation is a
sign of possible liver damage and can be detected on blood tests. However,
there are often no symptoms associated with high liver enzymes. Liver enzyme
elevation recurred in some patients who tried taking Avonex again.
The findings were seen in postmarketing data, says the Biogen letter. The
number of affected patients and details about them were not disclosed.
Some of the cases occurred in Avonex users who were also taking other drugs
that could cause liver problems, says the Biogen letter. The potential for
liver problems should be weighed when using Avonex with such drugs and products
that may affect the liver -- including alcohol.
The same risk should also be considered when adding new treatments to
patients already taking Avonex.
Pregnancy and Avonex
Biogen also made another change to Avonex labels. The revision encourages
doctors to enroll women who become pregnant while taking Avonex in the Avonex
Pregnancy Registry. "Avonex has not been studied in pregnant women,"
says the drug's web site.
Avonex is used to help treat MS symptoms. It's administered by injection
once a week.
In 2003, the FDA approved its use for people who had suffered only one MS
attack, as confirmed by brain scans. Avonex was the first drug to get approval
for those patients. Previously, it was typically used only for patients who had
experienced at least two MS attacks.
The most common side effects associated with Avonex include flu-like
symptoms, fever, fatigue, headache, chills, nausea, vomiting, and pain.
Cautions for Avonex use have already been noted for people with mood disorders
including depression. Patients with heart disease should also be closely
monitored while taking Avonex.