CYP2C9 e. Warfarin Tadalafil had no significant effect on exposure AUC to S-warfarin or R-warfarin, nor did tadalafil affect changes in prothrombin time induced by warfarin. Midazolam or Lovastatin Tadalafil had no drug effect on exposure AUC to midazolam or lovastatin. P-glycoprotein e. Digoxin Coadministration of tadalafil 40 mg once per day for 10 days did not have a significant effect on the steady-state pharmacokinetics of tablets 0. There are no data with the use of tadalafil tablets in pregnant women to inform any drug-associated risks for adverse developmental outcomes. Surviving offspring had normal development and reproductive performance. Based on the data from 3 studies in adult males, tadalafil decreased sperm concentrations in the study of 10 mg tadalafil for 6 months and the study of 20 mg tadalafil for 9 months. This effect was not seen in the study of 20 mg tadalafil taken for 6 months. There was no adverse effect of tadalafil 10 mg or 20 mg on mean concentrations of testosterone, luteinizing hormone or follicle stimulating hormone. The clinical significance of the decreased sperm concentrations in the two studies is unknown.