The use of intravenous zidovudine is suggested for women taking zidovudine monotherapy as per Recommendation 5.3.4. The use of intravenous zidovudine for women on HAART with a VL between 50 and 10 000 HIV RNA copies/mL can be considered regardless of mode of delivery.

However, continued oral dosing of their current regimen is a reasonable alternative. The effectiveness of zidovudine monotherapy in preventing MTCT was first demonstrated Pexidartinib in the ACTG 076 RCT of non-breastfeeding women in which zidovudine was initiated orally before the third trimester, given intravenously during labour and delivery, and orally to the neonate for the first 6 weeks of life, reducing MTCT by 67% [8]. Intravenous zidovudine has therefore been included in the management of all women treated with zidovudine monotherapy. However, the data on the contribution of intravenous zidovudine are poor. In a prospective study signaling pathway of all women prescribed zidovudine monotherapy during pregnancy before the publication of the ACTG 076 findings (1988–1994) in which the 8.8% transmission rate among women with CD4 cell counts >200 cells/μL is similar to that of the zidovudine monotherapy arm of ACTG 076 (8.3%), intrapartum intravenous zidovudine

was not associated with lower rates of transmission [51]. One rationale for intrapartum intravenous zidovudine in ACTG 076 was that labour would be associated with poor absorption of oral therapy. While not strictly comparable, the well-recognized rapid absorption of single-dose nevirapine during labour suggests that

the impact of labour on absorption may be overestimated. Pharmacokinetic data from an RCT of oral zidovudine monotherapy also vs. placebo indicate that adequate (therapeutic) zidovudine concentrations are achieved in cord blood with oral dosing. Although the concentrations are lower than have been reported with intravenous infusion, transmission was not associated with zidovudine cord blood concentration [52]. Intravenous zidovudine has historically been considered for women whose plasma VL has not been completely suppressed at the time of delivery. There is no evidence that the intravenous administration of zidovudine alters the rate of placental transfer but higher maternal plasma levels will be reflected in the cord blood concentrations. Intravenous zidovudine (as part of an intervention package; see Section 5: Use of antiretroviral therapy in pregnancy) has also been recommended for women who present in labour, having not received ART. However, data from the New York State HIV diagnostic service (1995–1997) suggest that intrapartum intravenous zidovudine alone does not significantly reduce transmission (10%; 95% CI 3.3–21.8%), as, provided neonatal prophylaxis is commenced within 48 h of delivery (this being the only intervention accessed), the latter has similar efficacy (9.3%; 95% CI 4.1–17.5%) [10].