Efavirenz
Efavirenz. NNRTI — non-competitive HIV-1 reverse transcriptase inhibitor. Strong CYP3A4 inducer + CYP2B6 substrate (poor metabolizers have very… Oral half-life 23 h.
NNRTI — non-competitive HIV-1 reverse transcriptase inhibitor. Strong CYP3A4 inducer + CYP2B6 substrate (poor metabolizers have very high AUC + CNS toxicity). Vivid dreams, depression, suicidality signal at therapeutic doses — modern regimens have largely moved past efavirenz.
PK: ITS OWN CITATION STATED TWO OF THESE NUMBERS AND THE RECORD GOT BOTH WRONG. That paper says "Oral clearance was 9.4 L/h, oral volume of distribution was 252 L, and the absorption rate constant was 0.3 h(-1)"; the record stored 0.5 and 390. The volume 390 appears in no efavirenz population model anywhere. All three published models call their volumes apparent, no intravenous formulation exists, and F 0.43 is the midpoint of a widely repeated 40-45% with no primary behind it — so F is pinned to 1 and the class-6 double division removed. THE RECORD NOW MOVES TO THE ONLY ONE-COMPARTMENT efavirenz MODEL PUBLISHED, matching this solver exactly: "Pharmacokinetic parameters were estimated according to a ONE-COMPARTMENT model ... oral clearance and the apparent volume of distribution were 9.50 liters/h and 311 liters". The half-life is that model own clearance-over-volume, derived inside a SINGLE fit rather than assembled across papers, and independently corroborated by a genotype study median of 23 h. MY AUTOINDUCTION PRIOR IS REFUTED AND THE RECORD MUST NOT BE STRIPPED: this is not a carbamazepine. The label reports accumulation only "22-42% lower" than predicted, against carbamazepine two- to threefold, so a single steady-state half-life can represent it. A POPULATION CAVEAT IS LOGGED INSTEAD: CYP2B6 genotype moves half-life from 23 to 48 hours.
Pharmacokinetics
- Oral — t½ 22.7 h · F 100% · ka 0.3 h⁻¹ · Vd 311 L
Sources: PMID:19433561, PMID:12545140, PMID:16392089