HIV Digest	HIV Digest Archive

Abacavir (Ziagen) is a nucleoside analog used in combination therapy for HIV infection. In about five percent of patients, abacavir causes a hypersensitivity reaction; if this occurs, the drug must be stopped and never restarted, and then the reaction will resolve on its own. The danger is that people unfamiliar with this side effect may not recognize it. If the drug is continued (or worse, stopped and restarted), the reaction can worsen and cause life-threatening hypotension (low blood pressure). The hypersensitivity reaction usually occurs within the first six weeks of treatment with abacavir; however, it can occur at any time during therapy.

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This risk of hypersensitivity to abacavir has long been known. But recently the FDA and Glaxo Wellcome changed the warning in the official labeling to point out that respiratory symptoms may be part of the hypersensitivity reaction. Shortness of breath has always been in the description; now cough and sore throat have been added. This is because some cases of hypersensitivity to abacavir were initially diagnosed as pneumonia, bronchitis, or respiratory tract illness.

Patients using abacavir who suspect they may have the hypersensitivity reaction need to contact their physician immediately. If this reaction occurs, the drug must be stopped. But the cost of stopping unnecessarily because of a false diagnosis of hypersensitivity reaction is that an important option will be lost. Therefore, when patients have symptoms suggestive of a hypersensitivity reaction, a careful evaluation by the health care provider is important.

Complete labeling for the drug, including the new information about the hypersensitivity reaction, is available at: www.glaxowellcome.com/pi/ziagen.pdf.

Editor's Note: from AIDS Treatment News