Pharmacokinetic interactions between depot medroxyprogesterone acetate and combination antiretroviral therapy

To evaluate the effect of an antiretroviral (ARV) therapy regimen containing zidovudine (AZT), lamivudine (3TC), and efavirenz (EFV) on the pharmacokinetics of depot medroxyprogesterone acetate (DMPA).

Open-label, nonrandomized, clinical trial.

University hospital clinic.

Thirty HIV-infected women; 15 using ARV therapy (AZT, 3TC, and EFV) and 15 non-users of ARV therapy, followed biweekly for 12 weeks.

Single injection of DMPA (150 mg IM) for both groups.

Pharmacokinetic parameters of DMPA by liquid chromatography with mass spectrometry, and ovulation by serum P.

Maximum serum concentrations of DMPA were reached at 14 days after injection. The area under the curve was similar in both groups, as were the minimum concentration, half-life, and clearance. Only 1 woman, not using ARV therapy, ovulated at 11 weeks after DMPA.

Pharmacokinetics of DMPA were similar in HIV-infected women, regardless of ARV therapy use, suggesting that triple therapy with AZT, 3TC, and EFV is not likely to interfere with the contraceptive effectiveness of DMPA.