Objective double-blind evaluation of erectile function with intracorporeal
papaverine in combination with phentolamine and/or prostaglandin E1.
Author(s): Allen RP, Engel RM, Smolev JK, Brendler CB.
Affiliation(s): Department of Urology, Johns Hopkins Hospital, Baltimore, Maryland.
Publication date & source: 1992, J Urol. , 148(4):1181-3
We performed a double-blind, crossover study using objective measurements to
compare maximum rigidity and duration of erections with papaverine hydrochloride
in combination with phentolamine mesylate and/or prostaglandin E1. The rationale
for the protocol was to combine a smooth muscle relaxant (papaverine) with either
or both vasodilating agents (phentolamine and prostaglandin E1) commonly used for
injection therapy. The 7 volunteer patients with organic impotence documented by
abnormal nocturnal penile tumescence testing were injected with 0.5 to 1.0 ml.
papaverine (30 mg./ml.) in combination with phentolamine (0.5 mg./ml.) and/or
prostaglandin E1 (5 micrograms./ml.). Each patient received 2 injections on each
of 2 testing dates; injection 2 was given after tumescence resulting from
injection 1 had subsided completely. The medications were given in a randomized,
counterbalanced order following double-blind procedures. Patients evaluated the
erections subjectively. In addition, the RigiScan device was used to measure
maximum rigidity and duration of erections. All patients observed increased
duration of erections with both combinations containing prostaglandin E1.
Analysis of RigiScan measurements showed no statistically significant differences
for maximum rigidity (p greater than 0.1) but significantly greater duration of
erections with papaverine plus prostaglandin E1, and papaverine plus phentolamine
plus prostaglandin E1 compared to papaverine plus phentolamine (p less than
0.001). There was no statistical difference in rigidity or duration of erections
between papaverine plus prostaglandin E1 and papaverine plus phentolamine plus
prostaglandin E1. No patient reported significant penile pain with any of the
injections. We conclude that the combination of papaverine and prostaglandin E1
produces erections of longer duration than papaverine plus phentolamine and that
no additional benefit is gained by adding phentolamine to a combination of
papaverine and prostaglandin E1. Further studies are in progress to define
optimal dose response curves for papaverine and prostaglandin E1 as individual
agents and in combination.
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