Background: Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor whose most common treatment limiting serious adverse events include rash and hepatitis. NVP is also known to reduce transmission of HIV from mother to fetus during pregnancy. Because of its widespread use during pregnancy, there is potential for serious morbidity and mortality for both the pregnant woman and her fetus should she develop a serious adverse event while pregnant. We anecdotally noted fewer serious adverse events among women who were initiated on NVP during pregnancy.  The purpose of this study was to determine whether pregnant women were less likely to develop an serious adverse event to NVP than non-pregnant women. 

Methods:  We conducted a case-control study using medical records for all women who received NVP at 2 institutions between September 1999 and July 2003.  Demographic data, CD4 counts, viral loads, concurrent medical therapies, and serious adverse events were extracted.  All serious adverse events observed within the first 90 days of NVP initiation were recorded and graded according to the ACTG scale.

Results:  The study population (n = 263) included 41 pregnant women (15.6%) and 222 non-pregnant women (84.4%).  The pregnant women were younger than the non-pregnant women (mean age 28.7 years for pregnant women vs. 38.0 years for non-pregnant women).  The mean CD4 counts and viral loads for the 2 groups were 474 cells/mm³ (range 93 to 1,290 cells/mm³) and 52,209 copies/mL (range 49 to 296,056 copies/mL ) for the pregnant women and 289 cells/mm³ (range 3 to 1490 cells/mm³)  and 379,119 copies/mL (range 49 to >750,000 copies/mL) for the non-pregnant women respectively. A total of 1 pregnant woman (0.4%) and 38 non-pregnant women (14.5%) developed an serious adverse events after starting NVP (OR = 8.26, 95%CI:  1.10 to  62.0, p = 0.0153).  Mild adverse events (grades 1-2) were seen in 1 (0.4%) pregnant woman and 21 (8.0%) non-pregnant women ( p = 0.1365), whereas serious adverse events (grades 3-4) were seen in 0 (0%) pregnant women and 17 (6.5%) non-pregnant women (OR=7.07, 95%CI:  0.41  to 119.87, p = 0.0675). In other bivariate analyses, risk of rash was independent of race, age, CD4 count, viral load, or other medications including hormonal contraceptives, antihistamines and corticosteroids.

Conclusions:  Although our results are limited by small sample size, women in our study were significantly less likely to develop an adverse reaction to NVP when the drug was initiated during pregnancy.

Keywords: nevirapine; rash; pregnancy