Rifabutin
Rifabutin. Spiropiperidyl rifamycin — narrower CYP3A4 induction than rifampin, used in HIV+TB co-treatment where rifampin would crater PI levels.… Oral half-life 36 h.
Spiropiperidyl rifamycin — narrower CYP3A4 induction than rifampin, used in HIV+TB co-treatment where rifampin would crater PI levels. Still meaningfully induces CYP3A4 (~40% AUC reduction of co-administered substrates).
PK: DO NOT STRIP THIS RECORD — IT IS EMPHATICALLY NOT THE CARBAMAZEPINE SHAPE, and two papers say so verbatim. "After repeated administration, induction of metabolism was indicated by lower AUC and Cmin values ... THE ELIMINATION HALF-LIFE WAS UNCHANGED AFTER REPEATED ADMINISTRATION ... induced systemic clearance (if any) should be of minor importance", and "Under autoinduction conditions, the elimination half-life of rifampicin decreases, whereas THAT OF RIFABUTIN IS NOT ALTERED." Carbamazepine was stripped because autoinduction moves its ELIMINATION parameter two- to threefold, so no single rate is valid; rifabutin induction lands on first-pass metabolism, which one steady-state bioavailability can hold. The magnitude cannot be established — no abstract states a number — and that is logged as an unsourceable gap rather than a strip trigger. F 0.16 was the computed midpoint of "Oral bioavailability was 12 to 20%" and becomes the verbatim "about 20% after single dose administration", the single-dose state this record models; the 12-20% range comes from patients already autoinduced at day 28. ka 0.7 implied a 5.28 h peak against a verbatim "about 2 to 3 h". CLASS 6 IS ACQUITTED — an intravenous tracer arm existed. A CLASS-13 NEAR-MISS IS RECORDED: a review states "The elimination half-life of rifabutin is long (45 hours)", but AT 45 h THE CLEARANCE TEST FAILS, falling below the verbatim 10-18 L/h floor, whereas 36 h is verbatim from a primary AND arithmetically consistent. KEEP 36.
Pharmacokinetics
- Oral — t½ 36 h · F 20% · ka 1.5 h⁻¹ · Vd 595 L
Related compounds
- Buprenorphine — caution
Sources: PMID:2552902, PMID:21596492, PMID:7736687, PMID:2177293, PMID:7698069