EXPERIENCES WITH THE NITRIC-OXIDE DONOR L INSIDOMIN (SIN-1) IN THE DIAGNOSIS AND TREATMENT OF ERECTILE DYSFUNCTION

A total of 113 nonseleted patients with erectile dysfunction of variou s etiologies and 10 normal control subjects underwent intracavernous p harmacotesting with the nitric oxide donor Linsidomin (SIN-1). 71/113 patients (62.8%) underwent additional pharmacotesting with a mixture o f papaverine (15 mg/ml) and phentolamine (0.5 mg/ml). All normal contr ol subjects had full rigid erections lasting 40-70 minutes. 78/113 pat ients (69%) had responses sufficient for intercourse, while 35/113 pat ients (31%) demonstrated inadequate response. All 44 patients who had rigid erections after application of SIN-1 had erections sufficient fo r intercourse with papaverine plus phenolamine in doses of 0.25 - 2 ml (mean 0.6 +/- 0.3 ml). From the total of 27 patients who had erection s insufficient for intercourse with SIN-1, 20 (74.1%) showed good resp onses with 0.25-2.0 ml P/P (mean 1.5 +/- 0.5 ml). 6/44 (13.6%) and 1/2 7 patients (3.7%) had prolonged erections with minimal to moderate dos es of papaverine plus phentolamine, respectively. No complications wer e seen after SIN-1 injections. 48 patients were enrolled in an auto-in jection program with SIN-1 to evaluate its safety and efficacy. After 10-150 injections/patient (total 1160 injections, mean 24.1 injections ) no significant side-effects such as prolonged erections were noted. Our data suggest that intracavernous SIN-1 is safe and efficacious in the majority of patients with erectile dysfunction, however, it has a lower smooth muscle relaxing effect than a combination of papaverine a nd phentolamine. Side effects with the combination of papaverine plus phentolamine are much more common. Linsidomin (SIN-1) seems to be the drug of choice in the diagnosis and treatment of patients who respond to minimal doses of conventional pharmacotherapeutic regimen and in pa tients who are at risk for priapisms.