Plasma conc may be decreased by UGT1A1, UGT1A3, UGT1A9, CYP3A4, P gp, & BCRP inducers. Plasma conc may be increased by UGT1A1, UGT1A3, UGT1A9, CYP3A4, P gp & BCRP inhibitors. Reduced absorption by certain antacids. Decreased plasma conc w/ etravirine. Potential life-threatening toxicity w/ dofetilide. Co-administration w/ St. John's wort is strongly discouraged. Mg/Al-containing antacids, Ca/Fe supplements, multivit, metformin.