A Cochrane review ² included 4 studies with a total of 1873 men with erectile dysfunction of different aetiologies. Two parallel group trials and one cross-over trial compared transurethral alprostadil with placebo, while one cross-over trial (n=45) compared intracavernous alprostadil with placebo. In meta-analysis of the two parallel trials, alprostadil was effective during follow-up in the "at least one successful intercourse" outcome (Peto Odds Ratio, OR 7.22, 95% CI 5.68-9.18). The one cross-over trial studying transurethral administration reported "at least one successful intercourse" in 64% of participants with at least one dose of alprostadil (P < 0.01 for each active dose versus placebo). In the other cross-over trial studying intracavernous administration, 39% of participants treated with 5 mcg alprostadil and 56% with 10 mcg reported a "complete erection". The overall self-evaluation was reported only for the 10 mcg group of which 56% of participants rated their response as "good" or "excellent". Adverse effects occurred more often and intensely as doses increased, penile pain (Peto OR 7.39, 95% CI. 5.40-10.12) and minor urethral trauma (Peto OR 3.79, 95% CI. 1.88-7.65) being predominant.

In a study ³ of intracavernous alprostadil involving 296 men with erectile dysfunction of various causes, all doses of alprostadil were superior to placebo, with increasing doses of alprostadil (from 2.5 to 20 mcg) resulting in higher response rates. In a six-month self-injection study (n=683), the participants reported being able to have sexual activity after 94% of the injections. The men and their partners rated the sexual activity as satisfactory after 87% and 86% of the injections, respectively. Penile pain, usually mild, occurred in 50% of the men at some time but after only 11% of the injections. Prolonged erections occurred in 5%, priapism in 1%, penile fibrotic complications in 2% and hematoma or ecchymosis in 8% of men.

In a comparative study ¹ of 103 unselected patients with erectile dysfunction, intraurethral alprostadil (MUSE, up to 1000 mcg) provided a total response rate of 43% as compared to 70% with intracavernous alprostadil (Prostavasin, up to 20 mcg). Complete rigid erections were reached in 10% of men in the former vs. 48% in the latter group. Penile pain/burning was reported 31.4% of intraurethral administrations as compared to 10.6% after intracavernous administration. Systemic side-effects like dizziness, sweating and hypotension occurred in 5.8% with syncope in 1% after intraurethral administraton. No circulatory side-effects were encountered after intracavernous alprostadil. Urethral bleeding after intraurethral application was observed in 4.8%.