In late July 2003 GlaxoSmithKline warned physicians that a three-drug combination of lamivudine (Epivir®), abacavir (Ziagen®) and tenofovir (Viread^TM) had failed to control HIV effectively in about half the treatment-naive patients in a clinical trial. The cause of the reduced response to this particular regimen is not known, but it may involve mutations causing cross-resistance to the drugs; Glaxo is also checking for chemical interactions inside the cell. The problem is not due to any one of the drugs; rather, for some reason this particular combination turned out not to work well.

The company advised:

"Abacavir and lamivudine in combination with tenofovir should not be used as a triple antiretroviral therapy when considering a new treatment regimen for naive or pre-treated patients;

"Any patient currently controlled on therapy with this combination should be closely monitored and considered for modification of therapy; and

"Any usage of this triple combination with other antiretroviral agents should be closely monitored for signs of treatment failure."

ISSN # 1052-4207

Copyright 2003 by John S. James. Permission granted for noncommercial reproduction, provided that our address and phone number are included if more than short quotations are used.