• The percentage of mothers with HIV-1 isolates with new NNRTI drug resistant mutations identified by genotypic sequencing of specimens collected within six weeks following delivery. [ Time Frame: baseline-48 weeks ]
  

• How many infants get HIV How many infants get HIV with resistance associated mutations How long the resistance remains [ Time Frame: baseline-48 weeks ]
  

Drug: Nevirapine (NVP)
Nevirapine 200mg once daily for 14 days followed by 200mg twice daily thereafter for the remainder of the treatment period. Combivir®, one tablet twice daily.
Drug: Zidovudine (ZCV) Drug: 3TC

An open-label, randomised, multicentre study to determine whether a regimen of single dose nevirapine combined with either 4 or 7 days of Combivir, compared to a regimen of single dose nevirapine, for the prevention of mother to child transmission can reduce the rate of development of drug resistant mutations of HIV-1, in HIV-1 infected pregnant women, who have not received antiretroviral therapy previously.

An interim analysis of the first 61 patients showed that a clinical and statistical difference exists between the occurrence of HIV-1 NNRTI resistant mutations in the single dose nevirapine only arm (50%) and the two other combination arms (9%). These findings partially answered the objectives outlined in the initial objectives. Consequently enrolment onto the single dose nevirapine arm was terminated. The objective of the trial was modified to compare whether either the 4 or the 7 day combination of ZDV+3TC and nevirapine would result in any significant reduction in the incidence of nevirapine resistance.

Study Hypothesis:

Evaluations of HIV-1 resistance patterns in trials of pMTCT have demonstrated nevirapine resistant HIV-1 isolates in approximately 15-20% of mothers 4-6 weeks after receiving either a single or two dose 200mg nevirapine regimen. Although the ability to detect these genotypic mutations decreases to 0% by about 18 months, it is not clear whether this resistance is clinically significant.(HIVNET 012).

Empirically then it would seem useful to develop a strategy to diminish the emergence of this early resistance, therefore this study is proposed to evaluate whether the effect of 4 or 7 days of 3TC+ ZDV added to a single dose nevirapine regimen for the prevention of MTCT will prevent the emergence of resistance to nevirapine.

Comparison(s):

ACTG 076, Thai, PETRA , HIVNET 006/012, SAINT