An Open-Label, Randomized, Flexible-Dose, Crossover Study to Assess the Comparative Efficacy and Safety of Sildenafil Citrate and Apomorphine Hydrochloride in Men with Erectile Dysfunction

Abstract

Introduction: We report the methodology and results of a study that compared a dopaminergic agonist, apomorphine, with a phosphodiesterase type-5 inhibitor, sildenafil, in terms of efficacy, tolerability, satisfaction and patient preference. Patients and Methods: This was a 20-week open- label, randomized, flexible-dose, crossover study to assess the comparative efficacy and safety of sildenafil and apomorphine. One sequence group received treatment with sildenafil followed by apomorphine and the other sequence group received treatment with apomorphine followed by sildenafil. The primary efficacy variable was the measurement of the score of the erectile function domain (the sum of questions 1–5 and 15) of the International Index of Erectile Function (IIEF) questionnaire. The secondary efficacy variables were: the responses to the Global Efficacy Assessment Questions; the score of the responses to all the questions of the IIEF questionnaire; the index score of the Erectile Dysfunction Inventory of Treatment Satisfaction questionnaire, and the event log variables. Resultsand Conclusions: A marked increase in the mean IIEF score was observed after treatment with sildenafil, compared with a small increase following treatment with apomorphine. The mean baseline and final scores before and after treatment with sildenafil were 13.9 ± 5.2 and 24.1 ± 5.2, while the corresponding mean scores before and after treatment with apomorphine were 14.2 ± 5.1 and 16.8 ± 6.2. The comparison between treatments showed a statistically significant difference in favor of sildenafil. Furthermore, sildenafil was found to be significantly superior to apomorphine in all the other secondary variables, produced a high level of patient satisfaction, and a significantly larger number of patients indicated their preference for sildenafil compared to apomorphine.

Mechanisms of Penile Erection and Basis for Pharmacological Treatment of Erectile Dysfunction

“…This limited efficacy, especially in patients with organic ED, which was confirmed in several studies (Perimenis et al, 2004a,b;Strebel et al, 2004;Gontero et al, 2005), leads to the suggestion that the drug could be best suited for men with mild ED. Subsequent comparative prospective studies between apomorphine SL and sildenafil provided clear evidence that sildenafil is more effective than apomorphine, and the high preference rates were in favor of sildenafil (Porst et al, 2007;Afif-Abdo et al, 2008;Giammusso et al, 2008;Pavone et al, 2008). Because of the superiority of sildenafil, apomorphine SL never reached noteworthy acceptance.…”

New Therapeutic Targets for the Treatment of Erectile Dysfunction

“…Pre‐incubation of these CC with Ang‐ [1–7] effectively attenuated Ang‐II induced contraction. Furthermore, corporal Ang‐ [1–7] infusion potentiated ICP rise induced by ES of the major pelvic ganglion in rats. Moreover, the attenuated erectile function in hypertensive rats was fully restored by Ang‐ [1–7] administration.…”

“…Ang‐ [1–7], another RAS member, induces CC relaxations even from older and diabetic rabbits. Pre‐incubation of these CC with Ang‐ [1–7] effectively attenuated Ang‐II induced contraction.…”

“…Ang‐ [1–7], another RAS member, induces CC relaxations even from older and diabetic rabbits. Pre‐incubation of these CC with Ang‐ [1–7] effectively attenuated Ang‐II induced contraction. Furthermore, corporal Ang‐ [1–7] infusion potentiated ICP rise induced by ES of the major pelvic ganglion in rats.…”

“…Besides PDE5 inhibitors, apomorphine is another orally available drug for ED, which acts centrally as a nonselective dopamine receptor agonist. Although frequently used in the past, it is almost never prescribed anymore because of its low efficacy [6].…”