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).
Half-Life (t½)
PO: 36h
Dosing Guidelines
PO: Typical 300 mg (Range: 150–300 mg)
Target Organ Systems
digestive
Interactions
Buprenorphine (caution): CYP3A4 induction (weaker than rifampin). McCance-Katz 2011 (PMID:21596492) verbatim: rifabutin "resulted in a significant decrease in buprenorphine plasma concentrations (35% decrease in AUC; p<0.001) no opiate withdrawal was seen". Same paper, head-to-head vs rifampin: rifabutin AUC ↓35%, NO withdrawal; rifampin AUC ↓70%, 50% withdrawal. Rifabutin clinically preferred for HIV/TB + opioid co-therapy. Ratio 0.65 → induction_factor 1.54.