Tadalafil Once a Day for Men with Erectile Dysfunction: Is It Superior than On-Demand Administration?

Background: Tadalafil is a PDE5I which has been licensed for the treatment of erectile dysfunction (ED) since 2003, is effective from 30 minutes after administration and its efficacy is maintained for up to 36 hours. More recently, it is also given OAD in a lower dose to allow spontaneous sexual activities. However, whether OAD administration is more effective than PRN administration in improving the EF is yet to be established.