[On-demand versus on-time dosing of tadalafil for erectile dysfunction: a prospective multi-center study].

Objective: To evaluate the safety and efficacy of tadalafil on demand and on time in men with erectile dysfunction.

Methods: We conducted a multi-centered randomized controlled study on 120 ED males, who were assigned to take tadalafil at 10 mg/ 20 mg on demand before sexual activity and at the same dose on time twice a week for 8 weeks. Before and at 4 and 8 weeks after treatment, and 1 month after withdrawal, we obtained the scores on IIEF-5, ED Inventory of Treatment Satisfaction (EDITS) and the short form of Psychological and Interpersonal Relationship Scales (SF-PAIRS) , and compared the safety and efficacy of medication between the two groups of patients.

Results: Totally, 110 patients accomplished the trial, 56 in the on-time and 54 in the on-demand group. At 4 and 8 weeks of medication and 1 month after withdrawal, the IIEF-5 scores were improved in both the on-time and on-demand groups, even more significantly in the former than in the latter at 8 weeks of treatment (21.6 +/- 2.9 vs 18.5 +/- 1.7) and 1 month after withdrawal (20.9 +/- 2.1 vs 17.9 +/- 2.3) (P < 0.05). The EDITS scores were significantly higher in the on-time than in the on-demand group at 8 weeks of treatment (31.7 +/- 6.9 vs 28.6 +/- 5.8) and 1 month after withdrawal (30.6 +/- 4.7 vs 27.9 +/- 6.5) (P < 0.05). The scores on the sexual self-confidence, spontaneity and time-concern domains of SF-PAIRS were remarkably improved after medication as compared with the baseline (P < 0.05), even more significantly in the on-time than in the on-demand group at 1 month after withdrawal. Both dosing schedules were well tolerated and no significant differences were observed in safety between the two groups.

Conclusion: On-time dosing of tadalafil is efficacious and well tolerated in the treatment of ED, and has an even better effect than on-demand dosing at 8 weeks of medication and 1 month after withdrawal.