[Response to intracavernous administration of 3 different drugs in the same group of patients with erectile...

To compare the subjective and objective penile rigidity in the same group of patients with erectile dysfunction after intracavernous injection of different vasoactive drugs.

91 impotent males were randomly assigned to three groups of intracavernous injection: A: 20 micrograms PGE1 B: 30 mg papaverine hydrochloride + 1 mg phentolamine (bimix), and C: 10 micrograms PGE1 + 15 mg papaverine hydrochloride + 0.5 mg phentolamine (trimix). Each patient was scheduled to receive the three modalities of intracavernous injection randomly with an interval of 7-10 days between injections. Penile rigidity equal to or more than 60% was considered positive. Subjective and objective penile rigidity were evaluated with callipers by the same observer.

82 patients completed the study and 9 dropped out after prolonged erection with one of the ICI modalities. Rigidity after treatment with C (66 +/- 15%) was significantly superior to that of B (59 +/- 15%, p = 0.0001) and A (60 +/- 13%, p = 0.0115). No differences were observed between A and B (p = 0.4644). Analysis of only the positive response showed significant differences between A and C, but not between C and B (p = 0.3323). Differences were not found between the response to PGE1 (A) and bimix (B) (p = 0.1275). The order of application of the drug had no effect on response (p = 0.026).

A higher percentage of positive response in patients with erectile dysfunction was achieved with the trimix modality. Choice of more potent ICI regimens can improve the diagnostic and/or therapeutic efficacy in males that do not respond to PGE1 alone.