PHARMACOKINETICS OF PROSTAGLANDIN-E1 AND ITS MAIN METABOLITES AFTER INTRACAVERNOUS INJECTION AND SHORT-TERM INFUSION OF PROSTAGLANDIN-E1 INPATIENTS WITH ERECTILE DYSFUNCTION

Purpose: Alprostadil (prostaglandin E1) is the preferred monotherapy f or intracavernous injection in the diagnosis and treatment of erectile dysfunction. Our study was designed to evaluate whether there is a di fference in the pharmacokinetics of prostaglandin E1 and its main meta bolites after intracavernous injection or short-term intravenous infus ion. In addition, we also investigated the influence of the erectile r esponse on prostaglandin E1 kinetics after intracavernous injection. M aterials and Methods: A total of 24 patients with erectile dysfunction received, in a randomized order at an interval of 5 hours, an intraca vernous injection or a 30-minute intravenous infusion of 20 mu g. of a lprostadil alfadex (prostaglandin E1). Venous blood samples were obtai ned 5 minutes before and at various times after the applications. We u sed highly sensitive gas chromatography/double-mass spectrometry metho d to measure prostaglandin E1 and its metabolites in plasma. Results: We demonstrated the presence of relevant systemic blood levels of pros taglandin E1 and its metabolites immediately after intracavernous inje ction. We found significantly lower systemic prostaglandin E1 concentr ations between 7 and 20 minutes after intracavernous injection in pati ents with an erectile response compared with those without. Conclusion s: We found significant systemic concentrations of prostaglandin E1 an d its metabolites after intracavernous injection. The systemic presenc e did not lead to significant changes in vital signs.