Effect of antiretroviral therapy including lopinavir/ritonavir or efavirenz on etonogestrel-releasing implant pharmacokinetics in HIV-positive women.

Carolina S Vieira, Maria V Bahamondes, Roberto M de Souza, Milena B Brito, Tatiana R Rocha Prandini, Eliana Amaral, Luis Bahamondes, Geraldo Duarte, Silvana M Quintana, Carolina Scaranari, Rui A Ferriani

Index: J. Acquir. Immune Defic. Syndr. 66(4) , 378-85, (2014)

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Abstract

Data on the interaction between the etonogestrel (ENG) implant and antiretroviral therapy are lacking. We evaluated the effect of 2 highly active antiretroviral therapy (HAART) regimens (1 including efavirenz and the other ritonavir-boosted lopinavir) on the pharmacokinetic (PK) parameters of an ENG-releasing implant in HIV-positive women.Prospective nonrandomized PK study.Forty-five HIV-positive women who desired to use ENG implants were included: 15 had received zidovudine/lamivudine + lopinavir/ritonavir for ≥3 months (LPV/r-based HAART group), 15 had received zidovudine/lamivudine + efavirenz for ≥3 months (EFV-based HAART group), and 15 had not received HAART (non-HAART group). PK parameters were measured using ultra-performance liquid chromatography-mass spectrometry at baseline and 2, 4, 6, 8, 10, 12, 16, 20, and 24 weeks after implant placement.The EFV-based HAART regimen was associated with a reduction in the bioavailability of ENG, which showed decreases of 63.4%, 53.7%, and 70% in the area under the curve (AUC), maximum concentration (Cmax), and minimum concentration (Cmin) of ENG, respectively, compared with the non-HAART group. The LPV/r-based HAART regimen was associated with an increase in ENG bioavailability, which showed 52%, 60.6%, and 33.8% increases in the ENG AUC, Cmax, and Cmin, respectively, compared with the non-HAART group.The coadministration of EFV decreased the bioavailability of ENG released from the implant, which could impair contraceptive efficacy. However, the coadministration of LPV/r increased the bioavailability of ENG released from the implant, which suggests that this antiretroviral combination does not impair the ENG implant efficacy.