HIV Treatment Bulletin (HTB) September/October 2009

s from the workshop, published in Reviews in Antiviral Therapy & Infectious Diseases 2011_3 are available to download from the meeting website. http://www.virology-education.com/index.cfm/t/Workshop_Materials/vid/34792068-01CF-4196-986A8271C014BBD7 Selected presentations are also available online. http://regist2.virology-education.com/2011/12HIV_PK/13_April.html Articles included in this issue of HTB are: • Quad reduces levels of oral contraceptives • Elvitegravir/cobicistat and acid reducing agents • Lopinavir/r reduces levels of rifabutin • Cobicistat has little impact on CYP2D6 and CYP2B6 • Atazanavir levels indicate need for higher dose during pregnancy • Once-daily 150-mg maraviroc explored in people taking atazanavir/ritonavir • Lopinavir troughs lower in children on once-daily dose with efavirenz • Dose optimisation: 50 mg ritonavir-boosting, 3TC dosing and raltegravir once-daily Quad reduces levels of oral contraceptives HIV-druginteractions.org This open‐label fixed‐sequence study investigated the pharmacokinetics of a combined oral contraceptive containing 25 ug ethinylestradiol and norgestimate with a fixed dose combination tablet containing elvitegravir, cobicistat, FTC and TDF (“Quad”). Steady‐concentrations of ethinylestradiol, norelgestromin (the active metabolite of norgestimate), EVG and cobicistat were determined in 15 HIV‐negative women receiving the oral contraceptive alone or with the “quad” tablet. Coadministration decreased the AUC of ethinylestradiol by ~25% and increased the AUC of norelgestromin by ~2‐fold. Concentrations of elvitegravir and cobicistat were within the range of values observed in previous studies. Changes in progesterone and FSH were similar in both treatment phases, but changes in LH were greater in the combination phase. In light of the decrease in ethinylestradiol, it is recommended that when coadministered with the “Quad” tablet, oral contraceptives should contain at least 30 μg ethinylestradiol. Ref: German P et al. EVG/cobicistat/FTC/TDF and oral contraceptives Pharmacokinetic interaction between norgestimate/ethinyl estradiol and EVG/COBI/FTC/TDF single tablet regimen. Oral abstract: O_17. Elvitegravir/cobicistat and acid reducing agents HIV-druginteractions.org The effects of omeprazole (20 mg once daily) or famotidine (40 mg once daily) on the pharmacokinetics of EVG and cobicistat were studied in HIV-negative subjects (n=11 per group). When omeprazole was administered 2 hours prior to elvitegravir and cobicistat the AUC and Cmax of elvitegravir increased by 10% and 16%, but those of cobicistat decreased by 8% and 10%. Separating omeprazole and EVG and cobicistat by 12 h had