PHOSPHODIESTERASE TYPE-5 INHIBITORS AND RIFAMPICIN (RIFAMPIN)

Tadalafil levels are reduced by 88% by rifampicin, by inhibiting CYP3A4. Rifampicin is predicted to reduce the levels of other phosphodiesterase type-5 inhibitors, which are also metabolised by CYP3A4.
If these phosphodiesterase type-5 inhibitors are not effective in patients taking
rifampicin, it would seem sensible to try a higher dose with close monitoring.