In the absence of a submission from the holder of the marketing authorisation, cobicistat (Tybost®) cannot be endorsed for use within NHS Wales as a pharmacokinetic enhancer of atazanavir 300 mg once daily or darunavir 800 mg once daily as part of antiretroviral combination therapy in human immunodeficiency virus‑1 (HIV‑1) infected adults and adolescents aged 12 years and older: weighing at least 35 kg co‑administered with atazanavir or weighing at least 40 kg co‑administered with darunavir.