Addition of zidovudine prophylaxis to nevirapine may reduce nevirapine-resistance in postnatal infection

Supplementing extended nevirapine prophylaxis with zidovudine significantly reduced the risk of nevirapine resistance at 14 weeks in infants who contracted HIV in utero, provided that the prophylaxis was stopped by 6 weeks of age, according to results from the Post-Exposure Prophylaxis of Infants-Malawi trial.

“Extended infant nevirapine prophylaxis reduces the risk of postnatal HIV transmission. However, it may induce resistance in infants who are HIV-infected despite prophylaxis,” Jessica Lidstrom, of the Johns Hopkins University School of Medicine, said during a presentation of the data at the 17th Conference on Retroviruses and Opportunistic Infections in San Francisco.

Lidstrom and colleagues evaluated levels of nevirapine-resistance in 88 infants infected with HIV despite treatment with extended nevirapine prophylaxis. At birth, the infants were randomly assigned to one of three regimens. The control group received single-dose nevirapine plus one week of daily zidovudine, the extended nevirapine group received the control regimen plus daily nevirapine for 14 weeks and the extended nevirapine plus zidovudine group received control plus daily nevirapine and zidovudine for 14 weeks. The researchers then analyzed plasma samples from the infants taken at 14 weeks for nevirapine-resistance.

“Overall, our findings showed that the addition of [zidovudine] to [nevirapine] reduced the risk of [nevirapine]-resistance in infants, with 65.6% of infants having [nevirapine]-resistance in the dual regimen arm while 86% of the infants had resistance in the [nevirapine]-only arm,” Lidstrom said.

The researchers also investigated the effect that the number of weeks that an infant received prophylaxis had on nevirapine-resistance. Although they found that supplementing extended nevirapine with zidovudine reduced nevirapine-resistance in infants infected at birth, longer periods of prophylaxis did not affect nevirapine-resistance.

For more information:

Lidstrom J. Comparison of NVP resistance among HIV-infected infants who received extended NVP plus ZDV prophylaxis vs. extended NVP prophylaxis alone: The PEPI-Malawi Study. Presented at: The 17th Conference on Retroviruses and Opportunistic Infections; Feb. 16-20, 2010; San Francisco.