Atazanavir exposure in pregnancy

A paper authored by Ripamonti Diego from the Division of Infectious Diseases, Ospedali Riuniti, Bergamo, Italy and coworkers, published in the November 30 edition of AIDS, reported findings from a study looking at the pharmacokinectics and placental transfer of boosted atazanavir in a group of HIV-positive pregnant women.

Seventeen women, receiving atazanavir boosted with ritonavir (plus AZT and 3TC) completed the study. A steady-state 24 hour pharmacokinetic evaluation of atazanavir was performed in the third trimester of pregnancy performed (38 ± 22 days, mean and SD) before delivery and postpartum. At the time of the evaluation the BMI of the women was 26.39 (SD ± 0.7), significantly (p<0.0001) higher than that reported from the postpartum evaluation (BMI 24.02 ± 0.6) performed 71 ± 45 days after delivery.

Maternal and cord blood samples were obtained at delivery. The atazanavir was measured by reverse-phase high-performance liquid chromatography.

The investigators found the antepartum atazanavir geometric mean AUC was 28 510 ng·h/l, the Cmax was 2 591 ng/ml and the Cmin was 486 ng/ml. The same postpartum parameters were 30 465 ng·h/l, 2 878 ng/ml and 514 ng/ml, respectively. The antepartum to postpartum ratio for AUC was 0.94 and for Cmin was 0.96 ie equivalent. Cmax values were slightly although not significantly lower.

The ratio of cord blood/maternal atazanavir concentration in 14 paired samples was 0.13.

The investigators concluded: As pregnancy does not appear to alter plasma exposure to atazanavir, no dose adjustment is required in pregnant women. Pharmacokinetic results suggest that a standard boosted atazanavir dose is a reasonable component of HAART during pregnancy.

Diego R, Dario C, Franco M et al. Atazanavir plus low-dose ritonavir in pregnancy: pharmacokinetics and placental transfer. AIDS. Volume 21(18),30 November 2007, p 2409-2415.