biostudies-literatureScarsi KKNational Institute of Allergy and Infectious DiseasesEunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNCATS NIH HHSNICHD NIH HHSNIAID NIH HHSNational Institutes of Health109951https://www.ebi.ac.uk/biostudies/studies/S-EPMC10187685biostudies-literatureUnknown121<h4>Objectives</h4>To determine if double-dose levonorgestrel emergency contraception (EC) in combination with efavirenz or rifampicin, 2 drugs known to decrease levonorgestrel exposure, resulted in similar pharmacokinetics compared to standard-dose levonorgestrel EC without drug-drug interactions.<h4>Study design</h4>We conducted a phase 2, open-label, multicenter, partially randomized, 4 parallel group trial in pre-menopausal females ≥16 years old without an indication for EC and not on hormonal contraception. Participants on dolutegravir-based antiretroviral therapy (ART) received levonorgestrel 1.5 mg (control group); those on rifampicin-containing tuberculosis therapy received levonorgestrel 3 mg; those on efavirenz-based ART were randomized 1:2 to levonorgestrel 1.5 mg or 3 mg. PlasmContraceptionPharmacokinetics of dose-adjusted levonorgestrel emergency contraception combined with efavirenz-based antiretroviral therapy or rifampicin-containing tuberculosis regimens.PMC10187685UM1 AI069423UM1 AI069521UL1 TR001422UM1 AI068634UM1 AI068636U01 AI068636U01 AI069463UM1 AI069463UM1 AI106701UM1 AI069456UL1 TR002384UL1 TR002489U01 AI069471UM1 AI069419UM1 AI069518R01 HD085887UL1 TR001857UM1 AI069494U01 AI069476U01 AI069399UM1 AI069471UM1 AI069432UM1 AI069399UM1 AI069476UM1 AI069453Smeaton LMBelaunzaran-Zamudio PFScarsi KKBarr EJalil EMGadama LMngqibisa RBadal-Faesen SGodfrey CPodany ATWoolley EGatechompol SOlefsky MCohn SEAIDS Clinical Trials Group A5375 Study TeamPham MSupparatpinyo KMawlana SfalsePharmacokinetics of dose-adjusted levonorgestrel emergency contraception combined with efavirenz-based antiretroviral therapy or rifampicin-containing tuberculosis regimens.<h4>Objectives</h4>To determine if double-dose levonorgestrel emergency contraception (EC) in combination with efavirenz or rifampicin, 2 drugs known to decrease levonorgestrel exposure, resulted in similar pharmacokinetics compared to standard-dose levonorgestrel EC without drug-drug interactions.<h4>Study design</h4>We conducted a phase 2, open-label, multicenter, partially randomized, 4 parallel group trial in pre-menopausal females ≥16 years old without an indication for EC and not on hormonal contraception. Participants on dolutegravir-based antiretroviral therapy (ART) received levonorgestrel 1.5 mg (control group); those on rifampicin-containing tuberculosis therapy received levonorgestrel 3 mg; those on efavirenz-based ART were randomized 1:2 to levonorgestrel 1.5 mg or 3 mg. Plasm2023-01-01T00:00:00Z2023 May2026-05-29T01:22:15.181Z2025-04-19T20:52:18.274ZS-EPMC101876853664109410.1016/j.contraception.2023.109951