Pharmacokinetics of prostaglandin E1 and its main metabolites after intracavernous injection and short-term infusion of prostaglandin E1 in patients with erectile dysfunction.

PURPOSE

Alprostadil (prostaglandin E1) is the preferred monotherapy for intracavernous injection in the diagnosis and treatment of erectile dysfunction. Our study was designed to evaluate whether there is a difference in the pharmacokinetics of prostaglandin E1 and its main metabolites after intracavernous injection or short-term intravenous infusion. In addition, we also investigated the influence of the erectile response on prostaglandin E1 kinetics after intracavernous injection.

MATERIALS AND METHODS

A total of 24 patients with erectile dysfunction received, in a randomized order at an interval of 5 hours, an intracavernous injection or a 30-minute intravenous infusion of 20 microg. of alprostadil alfadex (prostaglandin E1). Venous blood samples were obtained 5 minutes before and at various times after the applications. We used highly sensitive gas chromatography/double-mass spectrometry method to measure prostaglandin E1 and its metabolites in plasma.

RESULTS

We demonstrated the presence of relevant systemic blood levels of prostaglandin E1 and its metabolites immediately after intracavernous injection. We found significantly lower systemic prostaglandin E1 concentrations between 7 and 20 minutes after intracavernous injection in patients with an erectile response compared with those without.

CONCLUSIONS

We found significant systemic concentrations of prostaglandin E1 and its metabolites after intracavernous injection. The systemic presence did not lead to significant changes in vital signs.