Efficacy and Tolerability of Zidovudine 200 mg Twice a Day as Part of Combination Antiretroviral Therapy for 96 Weeks

Safety of zidovudine dose reduction in treatment-naïve HIV infected patients. A randomized controlled study (MiniZID)

BACKGROUND

Since September 2014, zidovudine (ZDV)-based therapy for HIV has been the preferred second-line WHO regimen in Cameroon, but its use is limited by the risk of anaemia at standard dosage. We assessed the safety of a reduced vs. standard dose of ZDV to decrease the risk of anaemia in treatment-naïve, HIV-infected individuals.

METHODS

In a prospective, randomized, open-label trial in an HIV clinic in Cameroon, 142 eligible adults (CD4 count < 350 cells/μL) were randomized to receive 24 weeks of a regimen comprising lamivudine plus nevirapine with either a reduced (400 mg) or standard dose (600 mg) of ZDV. The primary endpoint was the proportion of participants with new/worsening anaemia.

RESULTS

Median age was 35 years; 58.5% were women; median body mass index was 23.2 kg/m(2) . At baseline, median haemoglobin was 11.6 g/dL, median CD4 cell count was 163 cells/μL, and median plasma HIV-1 RNA load was 5.4 log10 copies/mL. The proportion of participants with new/worsening anaemia was 37.5% (400 mg ZDV) and 32.9% (600 mg ZDV) (P = 0.563). Ten patients with severe anaemia required a switch from ZDV to tenofovir (11.4% in standard-dose arm vs. 2.8% in low-dose arm; P = 0.054). At 24 weeks, there was no significant difference between treatment groups, including median CD4 T-cell count increases.

CONCLUSIONS

No significant difference was observed in the overall rate of anaemia between HIV-infected individuals starting a ZDV-based treatment according to a standard- or reduced-dose regimen. Severe anaemia and treatment switches related to study drug, however, were more frequent with 600 mg than 400 mg ZDV.

Potential effect of pharmacogenetics on maternal, fetal and infant antiretroviral drug exposure during pregnancy and breastfeeding

Mother-to-child-transmission rates of HIV in the absence of any intervention range between 20 and 45%. However, the provision of antiretroviral drugs (ARVs) during pregnancy, delivery and breastfeeding can reduce HIV transmission to less than 2%. Physiological changes during pregnancy can influence ARV disposition. Associations between SNPs in genes coding for metabolizing enzymes, and/or transporters, and ARVs disposition are well described; however, relatively little is known about the influence of these SNPs on ARV pharmacokinetics during pregnancy and lactation as well as their effect on distribution into the fetal compartment and breast milk excretion. Differences in maternal, fetal and infant ARV exposure due to SNPs may affect the efficacy and safety of ARVs used to prevent mother-to-child-transmission. The aim of this review is to provide an update on the effect of pregnancy-induced changes on the pharmacokinetics of ARVs and highlight the potential role of pharmacogenetics.