Objectives: To develop and test step-wise treatment strategy for erectile dysfunction "non-responders" to tadalafil and vardenafil.
Material and methods: Two groups [tadalafil-treated (TG); vardenafil-treated (VG)] of 100 consecutive patients complaining of non-response to treatments were enrolled in three-phase study. Phase 1: inadequate use was identified and patients were rechallenged, after receiving detailed usage information. Phase 2: true non-responders were given new instructions based on drugs' pharmacologic profiles: TGs were dosed at least 2 h before intercourse; VGs were dosed only in fasted state. Remaining non-responders entered phase 3: continuous administration of 20 mg tadalafil every other day, or 20 mg vardenafil every day for 2 weeks. Efficacy was based on positive (yes) response to two questions: "Were your erections rigid, and did they last long enough to have successful intercourse?" and "Do you want to repeat your prescription?"
Results: Tadalafil group: Inappropriate use was recognized in 32 patients; 14 (43.75%) responded after adequate instruction. Phase 2: 32 of 86 (37.2%) had intercourse at least 2 h after dose intake. Phase 3: 6 of 86 (11.1%) responded to continuous administration. Overall salvage rate was 52 of 100 (52%). Vardenafil group: Inappropriate use was recognized in 38 patients; 12 (31.58%) responded after adequate instruction. Phase 2, 22 of 88 (25%) responded to dosing in a fasted state. Phase 3: 12 of 66 (18.2%) responded to daily dosing. Overall salvage rate was 46 of 100 (46%).
Conclusions: Following proposed treatment strategy may maximize response rate to phosphodiesterase 5 inhibitors; appropriate usage instructions may play significant role in response rate.