Alprostadil in Erectile Dysfunction

Abstract

The underlying rationale behind pharmacotherapy of erectile dysfunction is to employ drugs that impair contraction or augment relaxation of the cavernous smooth muscle. At present, however, drugs that produce latter effect are more popular than the other. Among these, transurethral alprostadil (synthetic PGE1; MUSE®) and sildenafil (Viagra®) are widely used for the treatment of erectile dysfunction. Transurethral administration ofalprostadil at doses ranging from 125-1000 μg is effective in about 60% of patients regardless of the etiology of erectile dysfunction. The most common adverse event reported in approximately 30% of patients was penile pain. This pain was usually mild and only small proportion of patients discontinued the treatment because of it. Minor urethral trauma was found as high as 5% in some reports due to inappropriate administration technique. Such events can be minimized by proper counseling. Other side effects occurred in less than 5% of patients include dizziness and hypotension. Prolonged erection and penile fibrosis were rarely observed. Since the U.S. FDA approval in November 1996, approximately 1.0 million prescriptions for transurethral alprostadil have been filled. The average patient age is 60 years, and approximately 44% of patients have cardiovascular disease. Only one death in association with alprostadil has been reported to the U.S. FDA compared with 30 deaths in patients using sildenafil. More than 2.5 million prescriptions for this drug have been written since its approval by the U.S. FDA in March 1998. Therefore, the exposureadjusted incidence of drug-associated death with alprostadil seems to be lower than that reported for sildenafil. Reasons for this apparent discrepancy remain unclear. From efficacy and safety standpoint, transurethral alprostadil should be considered as one of the therapeutic options for erectile dysfunction.