Drug Therapy During Labor and Delivery, Part 1

Gerald G. Briggs; Stephanie R. Wan

Disclosures

Am J Health Syst Pharm. 2006;63(11):1038-1047. 

In This Article

Antiretroviral Drugs to Reduce Perinatal HIV-1 Transmission

The use of antiretroviral drugs during labor and delivery focuses on reducing perinatal transmission of HIV-1 from infected mothers to their newborn infants. CDC issued revised recommendations in November 2002, highlighting not only the use of zidovudine prophylaxis in the intrapartum period but also addressing the use of more aggressive combination-drug regimens throughout pregnancy, the appropriate care for women and infants presenting with no prior antiretroviral therapy, and the transmission risks related to mode of delivery.[50]

In 1994, the Pediatric AIDS Clinical Trials Group (PACTG) Protocol 076 revealed that relative perinatal HIV-1 transmission rates could be decreased by nearly 70% with the administration of a three-part zidovudine prophylactic regimen.[51] This regimen, consisting of maternal and infant zidovudine administration, has since been employed in developed countries, with dramatic reductions in perinatal transmission. The three-part regimen recommends antepartum administration of oral zidovudine to the mother (initiated at 14-34 weeks of gestation and continued throughout the pregnancy), intrapartum administration of zidovudine i.v. as a bolus dose followed by a continuous infusion until delivery, and then postnatal administration of oral zidovudine to the term neonate for the first 6 weeks of life.[51] Trans-placental passage of antiretroviral drugs plays an important role in infant protection; placental perfusion studies have demonstrated that zidovudine metabolizes to active triphosphate within the placenta, which may provide additional protection against in utero transmission.[52,53] Use of the intrapartum and postnatal components of the PACTG 076 zidovudine regimen is recommended for all HIV-1-infected pregnant women, regardless of their therapy throughout pregnancy.[50]

Additional antiretroviral regimens are available for HIV-1-infected women who have had no prior therapy and who present in labor. These regimens were studied in and intended for patients in underdeveloped nations where i.v. zidovudine is not readily available. CDC's publication, MMWR, provides more details on these regimens. Since most transmission of HIV-1 occurs near to or during labor secondary to intensive fetal exposure to HIV-1 in maternal genital secretions and blood, preexposure prophylaxis for the fetus can be provided by giving the mother agents to produce systemic antiretroviral drug levels.[50] When deciding which regimen to use, the clinician must weigh the advantages and disadvantages relating to the potential for synergistic inhibition of HIV replication with the use of combination therapy, known maternal-resistant viruses, standard recommendations, ease of drug administration and patient compliance, and cost. One regimen involving just one dose of intrapartum nevirapine to the mother and one dose to the baby postnatally has reduced perinatal transmission from HIV-1-infected women presenting in labor by 47%.[54] However, this regimen also raises concerns that increased development of resistant mutations to nonnucleoside reverse transcriptase inhibitors may occur in women exposed to this single-dose therapy.[55]

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