Patients who have not previously shown signs of hypersensitivity to the anti-HIV drug abacavir (Ziagen) are still at risk of severe, or even fatal, reactions when restarting the drug after a break, say regulatory bodies. A public statement issued by the European Agency for the Evaluation of Medicinal Products (EMEA) on August 14 says that prescribing and patient information for the drug has been modified through a rapid procedure at the request of the marketing authorisation holder.
The EMEA says that hypersensitivity reactions may occur just hours after treatment with abacavir is restarted, even in patients who have not previously been diagnosed as having a reaction to the drug. Such patients may only have had one of the main symptoms of hypersensitivity or, rarely, may have had no previous symptoms at all. A warning about the types of symptom that might indicate a hypersensitivity reaction was issued by the Committee on Safety of Medicines earlier this year (see PJ, February 19, p284). They include skin rash, fever, lethargy and gastrointestinal upset.
Glaxo Wellcome, the UK manufacturer of the drug, told The Journal on August 15 that it would be writing to doctors and probably also to pharmacists about the issue in the near future.
The public statement is available on the EMEA website www.eudra.org/humandocs/humans/ps.htm.

Key points for abacavir prescribing

• Patients who have stopped abacavir therapy because of a hypersensitivity reaction should never be given the drug again
• Abacavir must be discontinued if hypersensitivity cannot be ruled out, even when other diagnoses are possible (eg, influenza, gastroenteritis). If reintroduction becomes necessary, it must be done in a hospital setting
• Patients who stopped abacavir treatment for reasons other than hypersensitivity should only have the drug restarted if medical assistance is readily available
• Patients must be told that they might suffer a hypersensitivity reaction to abacavir and that they must contact their doctor immediately if they develop signs or symptoms that could indicate a reaction to the drug