Pharmacokinetics of total and unbound darunavir in HIV-1-infected pregnant women

Objectives: To describe the pharmacokinetics of darunavir in pregnant HIV-infected women in the third trimester and post-partum. Patients and methods: This was a non-randomized, open-label, multicentre, Phase IV study in HIV-infected pregnant women recruited from HIV treatment centres in Europe. HIV-infected pregnant women treated with darunavir (800/100 mg once daily or 600/100 mg twice daily) as part of their combination ART were included. Pharmacokinetic curves were recorded in the third trimester and post-partum. A cord blood sample and maternal sample were collected. The study is registered at ClinicalTrials.gov under number NCT00825929. Results: Twenty-four women were included in the analysis [darunavir/ritonavir: 600/100 mg twice daily (n=6); 800/100 mg once daily (n=17); and 600/100 mg once daily (n=1)]. Geometric mean ratios of third trimester versus post-partum (90% CI) were 0.78 (0.60-1.00) for total darunavir AUC<inf>0-tau</inf> after 600/100 mg twice-daily dosing and 0.67 (0.56-0.82) for total darunavir AUC<inf>0-tau</inf> after 800/100 mg once-daily dosing. The unbound fraction of darunavir was not different during pregnancy (12%) compared with post-partum (10%). The median (range) ratio of darunavir cord blood/maternal blood was 0.13 (0.08-0.35). Viral load close to delivery was <300 copies/mL in all but two patients. All children were tested HIV-negative and no congenital abnormalities were reported. Conclusions: Darunavir AUC and C<inf>max</inf> were substantially decreased in pregnancy for both darunavir/ritonavir regimens. This decrease in exposure did not result in mother-to-child transmission. For antiretroviral-naive patients, who are adherent, take darunavir with food and are not using concomitant medication reducing darunavir concentrations, 800/100 mg of darunavir/ritonavir once daily is adequate in pregnancy. For all other patients 600/100 mg of darunavir/ritonavir twice daily is recommended during pregnancy.

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