Pharmacokinetics of Antiretroviral Agents in HIV-1 Infected Pregnant Women

Overview

This study will determine if blood levels of anti-HIV drugs in pregnant women change at different stages of pregnancy and if these changes require dosage adjustments in order to maintain adequate drug levels during pregnancy. Anti-HIV medications are recommended for HIV-infected women during pregnancy not only to treat their infection, but also to reduce the chance of passing the virus to the baby during pregnancy. Changes in the body that occur during pregnancy may affect how the body uses and eliminates these drugs, reducing their levels during pregnancy. Pregnant women 18 years of age or older who are infected with HIV may be eligible for this study. Candidates will have a medical history and physical examination, pregnancy test and blood tests. Participants will come to the NIH Clinical Center once every 6 to 12 weeks until around their 34th week (8 months) of pregnancy and then again at least 1 month after the birth of the baby to have blood drawn. A catheter (thin plastic tube) will be placed in a vein to avoid multiple needle sticks for blood sampling during the day. The first sample will be collected before the patient takes the morning doses of anti-HIV medicines and additional samples will be drawn at 1, 2, 4, 8 and 12 hours after taking the medication. A urine sample will also be collected at each visit.

Highly active antiretroviral therapy is currently recommended for HIV-1 infected pregnant women for the management of maternal HIV infection and for prevention of perinatal HIV transmission. Many physiological changes occur during pregnancy may lead to changes in pharmacokinetics of drugs. Some of these pharmacokinetic changes may include increases in volume of distribution and total body clearance as well as decreases in oral absorption, area under the concentration time curve, peak and trough concentrations. All of these changes may result in decrease in drug exposure. Other than zidovudine, little is known about the pharmacokinetics of other antiretroviral agents during pregnancy. A number of studies have suggested a correlation between trough concentration: IC50 ratio and virological responses. The objective of the study is to examine the pharmacokinetics of antiretroviral agents during different stages of pregnancy in comparison with the non-pregnant state (post-partum and historical control). HIV infected pregnant women in general good health who are on at least three antiretroviral drug combination will be enrolled in the study. Pharmacokinetic profiles of the antiretroviral agents taken by the subjects will be obtained two to four times during pregnancy and again at around one month post-partum. These data will be used to assess the need for dosage adjustment or therapeutic drug monitoring of antiretroviral agents during pregnancy.