Objective: To compare the subjective and objective penile rigidity in the same group of patients with erectile dysfunction after intracavernous injection of different vasoactive drugs.
Methods: 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.
Results: 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).
Conclusions: 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.