ICAAC: No added benefit from adding AZT to nevirapine to prevent MTCT

Adding a short course of AZT (zidovudine, Retrovir) to nevirapine (Viramune) therapy does not reduce the rate of mother-to-child transmission of HIV, according to a study conducted in Zimbabwe and presented to the 45^th Interscience Conference on Antimicrobial Agents and Chemotherapy in Washington DC.

Earlier studies have shown that a short course of nevirapine can reduce the rate of mother-to-child transmission of HIV by 47% compared to a short course of AZT.

Investigators wished to see if providing a short course combination of nevirapine and AZT was more effective at preventing vertical transmission than nevirapine alone.

A double-blind, randomised, placebo-controlled trial was designed involving 1172 HIV-positive pregnant women attending the Salvation Army Howard Hospital in rural Zimbabwe. All the women received 200mg nevirapine during labour and all the infants received 2mg/kg nevirapine within 72 hours of birth. The women were randomised into one of two treatment arms. Women in Group A received an initial dose of 600mg of AZT followed by additional 300mg doses of the drug for every three hours of labour. Their infants also received 2mg/kg three times daily for 72 hours. The women and infants in Group B received placebo doses at the same intervals.

The study was terminated on the grounds of futility when an interim analysis was performed at week six. The investigators found that the rate of mother-to-child transmission was 46% in the study patients who received a combination of nevirapine and AZT, and 50% in the group who received nevirapine alone. The difference was not statistically significant.

“Short course AZT did not significantly decrease mother-to-child transmission when added to two doses of nevirapine”, conclude the investigators. They added that further follow-up was ongoing to see if adding AZT reduced the rate of nevirapine resistance.