The effect of re-dosing of vasodilators on the intracavernosal pressure and on the penile rigidity

Purpose: To study the effect of re-dosing of vasodilators on cavernous smooth muscle relaxation. Methods: The intracavernosal pressure (ICP) was measured in 48 patients undergoing an intracavernosal injection test followed by gravity cavernosometry before and after administration of 1 or 2 booster injections with 20 mu g prostaglandin E1 after an initial injection of a trimix of vasodilators. When submitted to Duplex scanning on another occasion, the injection of the trimix was followed by squeeze of the corpora. The occurrence of clinical full erection during the examinations was registered. Results: The mean values of the ICP changed little, albeit statistically significant, after the first booster injection (+3.47 mm Hg) but not after the second one. With cavernosometry, a false diagnosis of cavernous leakage was made in at least 14 patients. During Duplex scanning, after the corpora were squeezed, 12 patients developed a clinical full erection, but none did during the intracavernosal injection test, even after re-dosing. A minimal drop in blood pressure was observed in 15 subjects after a booster injection. Conclusions: Administration of booster injections of 20 mu g prostaglandin E1 after an initial injection of trimix did not induce sufficient cavernous smooth muscle relaxation. Squeezing of the corpora after injection of trimix was more successful.