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The pharmacokinetics of vasoactive substances injected into the corpus cavernosum for the treatment of erectile dysfunction have not been investigated to date. We measured the local intracavernous and peripheral venous concentration curves of papaverine and prostaglandin E1, and its primary metabolite 15-keto-13,14-dihydro-prostaglandin E1 in an intra-individual comparison after intracavernous injection. Papaverine was measured with high performance liquid chromatography and prostaglandin E1 was measured with a specially adapted radioimmunoassay. The results demonstrate that papaverine is slowly draining into the systemic circulation, showing slightly elevated levels in the peripheral blood 30 and 60 minutes after injection. Prostaglandin E1 shows a much faster decrease in local concentrations with no measurable increase in the periphery, probably due to the short half-time after lung passage. Measurement of the primary metabolite proves a local degradation of prostaglandin E1 in the corpus cavernosum into the biologically inactive 15-keto-13,14-dihydro-prostaglandin E1, which also shows a slight increase in the peripheral circulation due to the longer half-time of approximately 8 minutes. The data provide good explanation for the clinical finding of a markedly decreased incidence of priapism with the use of prostaglandin E1, which can be shown to be locally metabolized, compared to papaverine, which is retained in the corpus cavernosum in cases of nonvenogenic impotence.

Within a period of 3 1/2 years, 101 patients with drug-induced priapism lasting more than 6 h were observed. In 73 of the 101 patients (average age 47.4 years) with an average duration of priapism of 11.9 h priapism was interrupted by means including cavernosal puncture, evacuation, and injection of metaraminol. In 28 patients priapism subsided after an average duration of 8.8 h without medical intervention. Intracavernous blood gas analyses revealed unphysiological acid values with clearly negative excess base values. Nevertheless, in the present series only 3 patients had irreversible damage of cavernosal function as a sequela of priapism of more than 24 h duration. Intracavernosal injection of meta-ramininol was followed by severe hypertensive crisis in 2 patients. These results show convincingly that the demand for early interruption of drug-induced priapism within a time limit of 6 h is not based on objective necessity. Interruption of drug-induced priapism within 6-8 h seems to be adequate. Prostaglandin E1 has proved a reliable means of preventing priapism in the initial test period.

In the course of the evaluation of 500 patients with erectile dysfunction the results of penile Doppler-sonography and penile angiography could be compared in 65 patients, in whom both investigations were carried out under standardized conditions. Criteria for the evaluation of penile Doppler-sonography were the wave form analysis and especially the increase of blood-flow in the investigated arteries after intracavernous injection of papaverine. Criteria for the evaluation of the angiograms were the depiction of the penile arteries as well as the evidence of obstruction and collaterals of the internal iliac and pudendal arteries. In regard to the dorsal penile artery an all over correlation of 96.1% and in regard to the deep penile artery of 92.3% could be found. Based on these findings the conclusion can be drawn that papaverine-induced Doppler-sonography is able to replace penile angiography, thus no longer serving as the golden standard in the diagnosis of arterial insufficiency.

Based on 216 dynamic cavernosographies, performed in 25 patients with normal erectile capacity and in 191 patients with erectile dysfunction, an evaluation of this method in regard to its diagnostic validity in erectile dysfunction was possible. An additional comparison of the results of intracavernous application of vasoactive drugs with the outcome of dynamic cavernosography in 141 patients showed that a negative or clearly positive test-outcome indicated in over 90 per cent of the evaluated patients the presence or lack of venous insufficiency during dynamic cavernosography.