Nelfinavir- or nevirapine-containing HAART regimens during pregnancy are well tolerated. Side effects of antiretroviral therapy are more frequent in pregnant than in non-pregnant women.

ObjectivesOptimal plasma concentrations of antiretroviral drugs are required during pregnancy to treat maternal HIV infection and prevent mother-to-child transmission. We investigated the effect of pregnancy on nevirapine (NVP) plasma concentrations. MethodsWe included all HIV-1-infected women for whom NVP plasma concentrations were available as part of routine patient care at two university hospitals. Plasma NVP concentrations were compared for pregnant (n 5 45) and non-pregnant (n 5 152) women. Univariate and multivariate linear regression analyses were used to identify and adjust for other confounding factors associated with NVP plasma concentrations. For pregnant women who had a plasma NVP concentration available both during and outside pregnancy, a paired analysis was performed. ResultsSteady-state NVP plasma concentrations were lower in pregnant women: 5.2 mg/L (interquartile range 3.9-6.8) vs. 5.8 mg/L (4.3-7.7) (P 5 0.08). After adjusting for confounders, both pregnancy (regression coefficient 5 -0.90 mg/L, P 5 0.046) and African descent (regression coefficient 5 11.13 mg/L, P 5 0.005) influenced NVP concentrations significantly. The paired analysis showed mean concentrations of 4.8 mg/L during pregnancy and 5.8 mg/L outside pregnancy (paired t-test, P 5 0.073). ConclusionsPregnancy has a moderate but significant lowering effect on NVP plasma concentrations. Being of African descent compensates for the lowering effect of pregnancy on NVP concentrations.Keywords: HIV-1 infection, nevirapine, plasma drug concentrations, pregnancy IntroductionThe non-nucleoside reverse transcriptase inhibitor nevirapine (NVP) is widely used for the treatment of HIV-1 infection -especially in resource-limited settings, where it is often used in low-cost fixed-dose combinations.NVP is one of the drugs that can be used safely during pregnancy as part of highly active antiretroviral therapy (HAART) [1][2][3][4]. Pregnancy itself does not seem to increase the risk of toxicity [5]. Initiating NVP treatment is no longer recommended in women with CD4 counts above 250 cells/mL. However, many women are already on a HAART regimen containing NVP when they become pregnant, and this number is increasing because of the many programmes bringing HAART to resource-limited settings.Correspondence: Dr Jeannine FJB Nellen, Academic Medical Centre, F4-217, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands. Tel: 1 31 20 566 4380; fax: 1 31 20 697 2286; e-mail: f.j.nellen@amc.uva.nl DOI: 10.1111/j.1468-1293.2008.00551.x HIV Medicine (2008, 9, 234-238 r 2008 British HIV Association 234Pregnancy is accompanied by a variety of physiological changes that affect pharmacokinetics [6], resulting in lower plasma concentrations for several protease inhibitors (PI) [7][8][9][10]. NVP is metabolized through the cytochrome P450 isoenzymes CYP 3A4 (56%) and CYP 2B6 (32%) [11]. The upregulation of CYP 3A4 during pregnancy and the increase in volume of distribution might lead to lower NVP plasma concentrations during pregnancy [6,12,13]. There are no data on ...