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Timing of Dose Relative to Sexual Intercourse Attempt in Previous Sildenafil Citrate Users Treated with Tadalafil: A Geographical Comparison from a Single Arm, Open-Label Study


Gabrielle Gallagher, PhD, Intercontinental Information Sciences (ICIS), Eli Lilly Australia Pty Ltd, L1/16 Giffnock Avenue, Macquarie Park, Sydney, NSW 2113, Australia. Tel: (61) 2-88745769; Fax: (61) 2-88745733; E-mail:


Introduction.  Previous research has demonstrated that sildenafil citrate users alter dosing-sexual attempt behavior when switched to tadalafil. The impact of geography and culture on sexual behavior with phosphodiesterase type 5 (PDE5) inhibitor treatment has not been fully investigated.

Aim.  To describe and compare the changes in dosing-sexual attempt behavior with sildenafil citrate vs. tadalafil treatment across four distinct geographies: Asia, Australia/New Zealand (ANZ), Central Eastern Europe/Middle East (CEE/ME), and Latin America (LA).

Methods.  Data from a single-arm, open-label clinical trial conducted in 21 countries from November 2002 to May 2004 were used in this analysis. Men with erectile dysfunction and a history of ≥6-week prior sildenafil citrate use continued sildenafil citrate treatment for 4 weeks then switched to tadalafil for 8 weeks. Dosing instructions were provided.

Main Outcomes Measures.  Timing of dose and sexual intercourse was assessed through patient diaries for the final 4 weeks of each treatment period.

Results.  A total of 2,760 men were enrolled: Asia 15.8%; ANZ 29.4%; CEE/ME 19.7%; LA 35.1%. The median time from dosing to intercourse was significantly increased during tadalafil treatment across all geographical regions; however, the magnitude of increase differed significantly by geography (P < 0.0001). The Asian cohort demonstrated the shortest duration between dosing and sexual intercourse attempts (irrespective of drug), and altered sexual behavior the least upon switching to tadalafil. The ANZ cohort demonstrated the longest duration between dosing and sexual intercourse attempts (irrespective of drug), and altered sexual behavior the most upon switching to tadalafil.

Conclusion.  Men with a history of established sildenafil citrate use alter their dose-attempt behavior when treated with tadalafil irrespective of geography. However, the extent to which sexual behavior alters is not uniform across geographical regions, suggesting that dosing instructions and duration of drug effectiveness, in combination with personal and cultural preferences, may determine sexual behavior with PDE5 inhibitor use. Rubio-Aurioles E, Glina S, Abdo CHN, Hernandez-Serrano R, Rampazzo C, Sotomayor M, West TM, Gallagher GL, and Lenero E. Timing of dose relative to sexual intercourse attempt in previous sildenafil citrate users treated with tadalafil: A geographical comparison from a single arm, open-label study. J Sex Med 2009;6:2836–2850.