— Didanosine, the second drug approved for the treatment of HIV
infections and one of the oldest weapons in the AIDS armamentarium, has
been found to produce rare cases of potentially fatal liver disease in
patients taking it for long periods, the Food and Drug Administration
announced Monday.
Didanosine, marketed by
under the brand names Videx and Videx EC (an extended release version),
was approved by the FDA in 1991, joining AZT as the only drugs then
approved to treat HIV. It is a reverse transcriptase inhibitor,
blocking the action of the key enzyme used by HIV in replicating. It
has limited value when used alone because the virus rapidly mutates to
overcome it, and is thus generally used in drug cocktails.
In the 18 years since the drug has been on the
market, the FDA has received 42 reports of a rare disorder called
non-cirrhotic portal hypertension. It results when high blood pressure
occurs in the portal vein — a major vein of the liver — causing the
vein to enlarge and weaken. Once the vein wall is weakened, it can
split open, leading to fatal bleeding. Non-cirrhotic means that the
condition is not caused by cirrhosis of the liver, a consequence of
alcohol abuse.
Of the 42 cases, 26 were males, 14 were females and
no gender was reported for two. Their ages ranged from 10 to 66 years.
All had been taking the drug for months or years before the condition
developed. Four of the patients died from bleeding or organ failure.
Eight patients were treated by surgical techniques to reinforce the
vein or by a liver transplant. Only the three patients who had
transplants fully recovered.
The FDA concluded that the benefits of the drug
outweigh the risk, but is increasing the package warning to alert
physicians and patients to the possibility that the problem will
develop. The drug already has a box warning of an increased risk of
lactic acidosis and hepatomegaly with steatosis, caused by damage to
mitochondria in liver cells.
—
(c) 2010, Los Angeles Times.
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