INTRACAVERNOUS ALPROSTADIL - A REVIEW OF ITS PHARMACODYNAMIC AND PHARMACOKINETIC PROPERTIES AND THERAPEUTIC POTENTIAL IN ERECTILE DYSFUNCTION

Intracavernous alprostadil (synthetic prostaglandin E1) is a vnsodilat ing agent which acts by relaxing the smooth muscles of the corpus cave rnosum and by increasing the diameter of cavernous arteries; this lead s to erection. Following intracavernous administration, alprostadil is either locally metabolised or rapidly cleared from the penis into the systemic circulation where it is extensively metabolised by the lungs . Studies suggest that long term use of intracavernous alprostadil may increase penile blood flow, although the clinical relevance of this i s not currently known. In men with erectile dysfunction (ED), short te rm trials have shown that intracavernous alprostadil is superior or eq ual, in inducing erections, to other intracavernous agents such as pap averine, rite combination of papaverine plus phentolamine, linsidomine and topical nitroglycerin (glyceryl trinitrate). Intracavernous alpro stadil induced erections in around 70% of patients with ED of various origins in short term studies. 49 to 84% of patients accept the offer of joining self-injection programmes and 13 to 60% of these patients w ithdraw from such programmes for a variety of reasons. At therapeutic doses, intracavernous alprostadil is well tolerated. The most common a dverse event of transient penile pain occurred in around one-third of patients and in 11% of injections, causing 3 to 5% of patients to with draw from self-injection programmes. Potentially serious adverse event s such as priapism and fibrosis occurred in 4 and 8% of patients. Over all, available data suggest that the efficacy of intracavernous alpros tadil is superior or equal to that of other erectogenic agents which a re in use. Furthermore, the drug is well tolerated especially with reg ard to serious adverse events, Thus, although further research is nece ssary To confirm its use in combination with other agents, alprostadil appears likely to become the intracavernous agent of choice for the m anagement of erectile dysfunction.