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Rochira V, Granata ARM, Balestrieri A, Madeo B, Carani
C. Effects of sildenafil on nocturnal penile tumescence and rigidity in normal
men: randomized, placebo-controlled, crossover study. J
Androl.2002
;23:566–571.
In an effort to understand the actual duration of the effects of sildenafil on penile erection in normal men, the authors have decided to elegantly evaluate nocturnal penile tumescence erections and rigidity in a group of men with normal erectile activity. They use nocturnal penile tumescence monitoring to monitor sleep-related erections after taking either sildenafil or placebo.
The data show, quite interestingly, that in these normal individuals sildenafil did enhance nocturnal erectile activity. Sildenafil increased the total duration of rigidity, the total number of valid erections, and the maximum rigidity and maximum increase in tumescence and total duration of increase in penile circumference. The majority of these parameters were significantly increased after sildenafil. It is interesting that the effects were observed over the course of 4 hours, and in some individuals the effects were observed over the course of 8 hours.
These interesting data shed a great deal of light on the current anecdotal experience of many clinicians vis à vis the use of sildenafil. These data suggest that sildenafil has long-lasting effects on some individuals, perhaps up to 8 hours. These data explain why certain individuals may be able to take sildenafil at night and to use the morning erection for intercourse. All in all, these data add significantly to the body of literature regarding sildenafil and the ability of a man's erectile function to improve over the course of several hours. These data also suggest that the erectile function remains improved over the course of the time evaluated herein, 4 hours or 8 hours.
The obvious downside of this finding is that now we have evidence to suggest that the effects of sildenafil may be longer lasting than was previously believed. The questions to ask include, what is the long-term effect of this on nonsexually stimulated erectile activity; what is the effect of this result on men with abnormal erectile activity; will this drug have any untoward effect on penile physiology with respect to nitric oxide or cyclic guanosine monophosphate production at the level of the penis; and should we be concerned about any other issues in light of these new data?
This study is very useful and offers great insight into the duration of sildenafil-mediated effects on sleep-induced erectile activity. However, it also raises new questions that will need to be addressed in future studies. The authors are to be congratulated for a novel design that sheds light and offers new and important information on the physiology of erections under the influence of sildenafil.
Rochira V, Granata ARM, Balestrieri A, Madeo B, Carani C. Effects of sildenafil on nocturnal penile tumescence and rigidity in normal men: randomized, placebo-controlled, crossover study. J Androl.2002 ;23:566–571.
Sildenafil improves sleep-related erections in men with (Montorsi et al, 2000) and without erectile dysfunction. Does this mean that sildenafil can also improve erections in normal men during sexual activity, and if it does, would use of sildenafil for this purpose be appropriate? Would use of sildenafil for this purpose lead to any negative effects? In clinical practice, keeping in mind that sleep-related erections are only slightly, if at all, affected by external factors, would nocturnal penile erection monitoring after sildenafil administration be useful in order to discriminate nonresponding from responding patients?
Our study suggests a prolonged efficacy of sildenafil, at least on nocturnal penile erections. In this view, future research could investigate the possible therapeutic effect of frequent sildenafil administration (eg, once or twice weekly before bedtime) on erectile dysfunction, even though sildenafil administration is not strictly linked to a following sexual activity.
Future studies could be helpful in developing new strategies for the use of sildenafil.
References
Montorsi F, Maga T, Strambi LF, Salonia A, Barbieri L, Scattoni V, Guazzoni G, Losa A, Rigatti P, Pizzini G. Sildenafil taken at bedtime significantly increases nocturnal erections: results of a placebo-controlled study. Urology.2000; 56:906 -911.[Medline]
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