ORIGINAL RESEARCH—ED PHARMACOTHERAPY
Timing of Dose Relative to Sexual Intercourse Attempt in Previous Sildenafil Citrate Users Treated with Tadalafil

https://doi.org/10.1111/j.1743-6109.2006.00220.xGet rights and content

ABSTRACT

Objectives

Tadalafil, a phosphodiesterase type 5 inhibitor, has an extended period of effectiveness, up to 36 hours, for the treatment of erectile dysfunction (ED). Changes in behavior of long‐term sildenafil users were evaluated by assessing time of dose relative to sexual intercourse attempts during treatment with sildenafil and tadalafil.

Materials and Methods

This open‐label study was conducted in men with ED and a history of ≥6‐week prior sildenafil use in Australia, New Zealand, Asia, Central and Eastern Europe, the Middle East, and Latin America. Patients continued sildenafil treatment for 4 weeks, then switched to tadalafil for 8 weeks. Timing of sexual intercourse attempt relative to dose was assessed through patient diaries for the final 4 weeks of each treatment period. Patients continued their treatment of choice in an extension period.

Results

A total of 2,760 men (mean age 54.4 years) with a median duration of prior sildenafil use of 474 days were enrolled. Significant increases in median time from dose to intercourse attempt were observed when changing treatment from sildenafil citrate (1.21 hours) to tadalafil (3.25 hours; P < 0.001). Fifty‐nine percent of intercourse attempts were within 4 hours of dosing when patients were treated with tadalafil (88% with sildenafil). The proportion of intercourse attempts per patient made >4 hours after dose was considerably higher during the tadalafil than during the sildenafil assessment period. Similar daily cycles of frequency of dosing and intercourse attempts were observed in all study periods and were characterized by a small peak in the morning and a large peak in the evening. When changing treatment to tadalafil, patients administered the drug earlier in the day and over a broader period of time.

Conclusion

Following the dosing instructions reflecting tadalafil's extended period of effectiveness, men with a history of established sildenafil use changed their dose‐attempt behavior when treated with tadalafil. Glina S, Sotomayor M, Gatchalian E, Yaman O, Dyachkova Y, Markey C, and V Kopernicky. Timing of dose relative to sexual intercourse attempt in previous sildenafil citrate users treated with tadalafil. J Sex Med 2006;3:309–319.

Introduction

Therapeutic options for the treatment of erectile dysfunction (ED) have expanded significantly with the introduction of phosphodiesterase type 5 (PDE5) inhibitors. These oral therapies afford patients a noninvasive treatment and are favored by men with ED [1]. While all PDE5 inhibitors interfere with activity of the PDE5 enzyme [2], they differ substantially in their pharmacokinetic profile and duration of action. According to its reported clinical effectiveness, patients taking sildenafil citrate (sildenafil) are commonly instructed to take the medication up to 4 hours before sexual activity [3]. In contrast, tadalafil has been shown to be effective up to 36 hours after dose [4].

Results from studies with tadalafil examining timing of sexual behavior indicate that patients with ED use the 36‐hour period of tadalafil regardless of age, ED severity, or previous sildenafil use [5, 6]. Little is known about sex patterns of men treated for ED, specifically whether differences in the therapeutic window and related dosing instructions are associated with changes in patients’ sexual behavior when using different PDE5 inhibitors.

The goal of this study was to examine to what extent prior sildenafil users modified their sexual intercourse and drug intake timing behavior when exposed to tadalafil with respective dosing instructions. It is not known how sildenafil experienced patients change their behavior with new dosing instructions that suggest a broader window of opportunity from dose to sexual intercourse (while on tadalafil). Patients recruited into this large, multinational study were current users of sildenafil who, having completed a minimum of 10‐week continuous treatment with sildenafil (including 4 weeks on‐study), were then switched to treatment with 20 mg tadalafil.

Section snippets

Study Population

A total of 2,760 patients from 173 centers in 21 countries (Malaysia, Taiwan, Hong Kong, Philippines, Singapore, Australia, New Zealand, Czech Republic, Poland, Russia, Slovakia, Turkey, Israel, Brazil, Peru, Venezuela, Colombia, Mexico, Costa Rica, Chile, and Puerto Rico) participated in the study.

Men were eligible for the study if they were at least 18 or 21 years of age (depending on country requirements) and had at least 3‐month history of ED (defined as a consistent change in the quality

Subjects

Enrolled patients were of diverse ethnicity and showed predominantly a moderate severity of ED (66%) as assessed by the investigator. The median duration of sildenafil use prior to enrollment was 474 days and the most commonly used doses of sildenafil were 50 mg (60.5%) and 100 mg (34.2%). Baseline patient characteristics are presented in Table 1.

Of the 2,760 men enrolled in this study, 269 did not complete all visits. For those patients who did not complete the study, 96 withdrew during the

Discussion

Sex patterns of men taking treatment for ED may be influenced by multiple factors including biological, social, psychological, and cultural. The goal of the present study was to provide insight into the behavior of long‐term sildenafil users, when treated with tadalafil and receiving specific dosing instructions. Although statistically significant differences were observed between treatments for drug exposure and frequency of sexual intercourse attempts per week, these may not be clinically

Conclusion

Therapeutic options for oral treatment of ED differ in their pharmacological profile and duration of action. The present study attempts to show that when previous sildenafil users changed their treatment to tadalafil and were instructed to explore its period of efficacy, they altered their timing of dose to sexual intercourse attempts. Specifically, these patients showed a propensity to administer tadalafil more in advance of sexual activity and earlier during the day compared with their

Acknowledgments

The authors would like to acknowledge the invaluable contribution of all site investigators who participated in the study. In addition, we are very grateful to Philippa Clarke and Zbigniew Kadziola for their contribution to statistical analysis of the study data.

Conflict of Interest

Funding for this study was supported by Lilly‐ICOS LLC. Yulia Dyachkova and Vladimir Kopernicky are employees of Eli Lilly and Company. Caroline Markey was an employee of Eli Lilly and Company during the study and is currently employed by Novartis. Mariano Sotomayor is a member of Lilly and Bayer advisory boards. Sidney Glina is a member of Bayer, Lilly ICOS, and Pfizer advisory boards and is a clinical investigator for GlaxoSmithKline, Pfizer, and Jansen‐Cilag.

References (12)

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