Dangarembizi B, et al. - In view of the observation that HIV-infected children younger than 36 months show improved efavirenz (EFV) exposures when receiving CYP2B6 516 genotype-directed dose, researchers sought to obtain the data in those with tuberculosis (TB) coinfection via conducting phase I, 24-week safety and pharmacokinetic study of EFV in HIV-infected children aged 3 to <36 months, with or without TB. As per CYP2B6 516 genotype, they classified children into extensive metabolizers (516 TT/GT) and poor metabolizers [(PMs), 516 TT]. They recruited 14 children from 2 African countries and India with HIV/TB; 11 were aged 3 to <24 months and 3 were aged 24–36 months, 12 extensive metabolizers and 2 PMs. Children with HIV/TB coinfection received 25%–33% higher EFV doses targeting EFV area under the curve 35–180 μg × h/mL, with individual dose adjustment as necessary. Outcomes support the safety of using genotype-directed dosing for achieving therapeutic EFV concentrations and virologic suppression in HIV/TB-coinfected children younger than 24 months. However, they recommend performing a further study to confirm appropriate dosing in those aged 24–36 months. They suggest this approach as most important for young children and currently a critical unmet necessity in TB-endemic countries.