Summary: The goal of this clinical study is to provide continued access to the study drug(s) to children and adolescents with human immunodeficiency virus type 1 (HIV-1) who completed their participation in an applicable parent study and to monitor for adverse events. The primary objectives of this study are as follows: * To provide continued access to the study drug received in the parent protocol or swit...

Summary: The purpose of the study is to evaluate the pharmacokinetics (PK) of Suzetrigine (SUZ) and its metabolite in the absence and presence of efavirenz, a moderate CYP3A inducer. In addition, the purpose is to evaluate the safety and tolerability of SUZ when administered in the absence and presence of efavirenz.

Summary: The main goal of this clinical study is to test how CYP2B6 genetic variations and efavirenz (cornerstone in HIV-1 therapy) dictate the disposition (PK) of CYP2B6 substrate (methadone) and PK and effect (PD) of CYP1A2 substrate (tizanidine). Specifically, the investigators will test whether efavirenz produces CYP2B6 genotype dependent unanticipated DDIs with CYP2B6 (methadone) and CYP1A2 (tizanidin...