Effects of oral phentolamine, taken before sleep, on nocturnal erectile activity: a double-blind, placebo-controlled, crossover study

Abstract

The objective of this study was to determine the effects of oral phentolamine, administered before sleep, on nocturnal penile erectile activity of men with mild to moderate erectile dysfunction (ED). We studied five patients with mild to moderate ED (mean age 34.8 AE 8.13 and mean duration of ED 31.8 AE 23.5 months), in a double-blind, placebo-controlled, crossover study. All patients received oral phentolamine (Vasomax TM ) at a dose of 40 mg and placebo for three consecutive nights respectively and were submitted to nocturnal penile tumescence and rigidity monitoring (NPTR) with the Rigiscan 1 device. NPTR parameters of the two 3-night recordings were evaluated and compared. Administration of oral phentolamine before sleep was associated with a statistically significant increase in the number of erectile events with rigidity ! 60% lasting ! 10 min (P ¼ 0.02), as well as the rigidity activity units (RAU) value per hour sleep, both at the base (P ¼ 0.023) and the tip of the penis (P ¼ 0.019). The number of events as measured by Rigiscan software (20% change in circumference), as well as tumescence activity units (TAU)=h values did not show any statistical difference. No adverse effects were recorded. It is concluded that oral phentolamine administered before sleep enhanced NPTR parameters associated with the quality of the erectile events. Such results provide a pathway for the development of a prevention strategy for ED. Future studies will elucidate whether vasoactive agents taken on a regular basis before sleep, can prevent ED in men at risk, protecting also minimally and moderately impotent patients to become moderately and severely impotent respectively.

Phentolamine relaxes human corpus cavernosum by a nonadrenergic mechanism activating ATP-sensitive K+ channel

“…6 Some studies have shown the relative efficacy of this formulation for long-term preventive pharmacological treatment of ED for men with mild to moderate ED. [14][15][16] One study has shown no difference in the success rate of sexual intercourse of patients treated with phentolamine or sildenafil. 17 The inhibition of the physiologic sympathetic tonus by phentolamine leads to relaxation of the HCC.…”

Diagnostic Tests for Male Erectile Dysfunction Revisited

“…A recent biomechanical study supporting the validity of the measurement of axial rigidity puts an end to this debate [64]. To date, the assessment of sleep-related erections is predominantly used in studies to quantify the erectogenic effect of oral agents and the potentially anti-erectogenic effects of medical interventions and environmental agents [65][66][67][68][69][70][71][72][73][74][75][76]. The clinical value is not well established or accepted.…”

Testosterone and Sleep-Related Erections: An Overview*

“…An interesting question is whether the administration of common vasoactive drugs for established ED can increase the nocturnal erectile activity. Montorsi et al [86] and Hatzichristou et al [87] administered either sildenafil or phentolamine orally at bedtime, respectively, and showed that in most patients with ED and goodsleep efficiency, the treatment significantly improved the quality of SREs. However, it has to be pointed out here that both studies excluded hypogonadal patients and patients with ED resulting from a radical prostatectomy.…”