1. ¹Department of Medicine, University of Rochester Medical Center, Rochester, NY, USA
2. ²Center for Biostatistics in AIDS, Research, Harvard School of Public Health and Frontier Science and Technology Research Foundation, Boston, MA, USA
3. ³Center for Research for Mothers and Children, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
4. ⁴Department of Obstetrics/Gynecology, University of Southern California School of Medicine, Los Angeles, CA, USA
5. ⁵Department of Obstetrics/Gynecology, University of Washington School of Medicine, Seattle, WA, USA
6. ⁶US Medical, Pfizer Global Pharmaceuticals, Pfizer Inc., New York, NY, USA
7. ⁷Department of Medicine and Pharmacology, Tulane-LSU-Charity Hospital GCRC, Tulane University Health Sciences Center, New Orleans, LA, USA

Correspondence: SE Cohn, (Susan_Cohn@urmc.rochester.edu)

⁸Current address: Clinical Pharmacology Program, NIH Clinical Center, National Institutes of Health, Bethesda, MD, USA

Received 9 July 2006; Accepted 13 October 2006; Published online 27 December 2006.

Abstract

We conducted an open-label, steady-state pharmacokinetic (PK) study of drug interactions among HIV-infected women treated with depo-medroxyprogesterone acetate (DMPA) while on nucleoside analogues plus nelfinavir (N=21), efavirenz (N=17), or nevirapine (N=16); or nucleosides only or no antiretroviral therapy as a control group (N=16). PK parameters were estimated using non-compartmental analysis, with between-group comparisons of medroxyprogesterone acetate (MPA) PKs and within-subject comparisons of ARV PKs before and 4 weeks after DMPA dosing. Plasma progesterone levels were measured at baseline and at 2, 4, 6, 8, 10, and 12 weeks after DMPA dosing. There were no significant changes in MPA area under the concentration curve, peak or trough concentrations, or apparent clearance in the nelfinavir, efavirenz, or nevirapine groups compared to the control group. Minor changes in nelfinavir and nevirapine drug exposure were seen after DMPA, but were not considered clinically significant. Suppression of ovulation was maintained.