Reuters 1 February 2001

London -- Doctors throughout Europe are being warned of a potentially fatal side effect if pregnant women infected with HIV take Bristol-Myers Squibb's AIDS drugs Zerit (stavudine) and Videx (didanosine).

In a public statement, the European Medicines Evaluation Agency (EMEA) said seven cases of lactic acidosis--three of them fatal--had been reported worldwide in pregnant women taking the two drugs in combination.

Lactic acidosis occurs when the body's cells are unable to convert food into usable energy. The condition causes excess acid to accumulate in the body, potentially damaging vital organs such as the liver and pancreas.

Echoing last month's warning by the US Food and Drug Administration (news - web sites), the EMEA pointed out that lactic acidosis is a known side effect of the class of HIV drugs called nucleoside reverse transcriptase inhibitors (NRTIs). The use of this class of drugs is not recommended during pregnancy unless the potential benefit clearly outweighs the potential risks.

Two of the deaths occurred in women taking part in a multinational clinical study--one in a patient taking the triple combination therapy didanosine/stavudine/nelfinavir, the other in a patient on didanosine/stavudine and an experimental protease inhibitor.

The statement said there was insufficient information to decide whether pregnancy is an additional risk factor for lactic acidosis. "It is also uncertain whether any increased risk of lactic acidosis is specific to stavudine and didanosine or whether it might be increased with all combinations of nucleoside analogues.''

It added that the EMEA's scientific committee and national agencies had requested more information from all companies marketing NRTIs so that they could evaluate the whole issue.

A company spokeswoman in Brussels told Reuters Health that the three dead women were from the UK, South Africa and Argentina.

The company is distributing the EMEA's public statement to doctors in Europe.

She said deciding how to treat HIV-infected women who became pregnant was a "big issue'' for doctors, particularly if the women were already resistant to some antiretroviral therapies.