Apomorphine SL (TAP Holdings, Deer®eld, IL) is a centrally acting treatment for erectile dysfunction (ED) that has been undergoing phase III trials. Over 3000 men have received apomorphine SL and over 75,000 doses have been taken. In the ®rst three phase III parallel arm cross-over double-blind studies 854 patients were given a total of 8263 tablets of apomorphine SL in 2 and 4 mg doses. The patients were between 18 and 70 y old and outcome measures included per attempt rates of intercourse and erections ®rm enough for intercourse as well as psychometric instruments and partner responses. The majority (74.1%) had moderate and severe grades of ED on admission to the studies, 31% had hypertension, 16% had documented coronary artery disease, 16% had dyslipidemia and 16% had diabetes. Erections occurred rapidly (10 ± 25 min) and in 54.4% of attempts at 4 mg (vs 33.8% placebo). A majority of the attempts at intercourse (50.6%) were successful at 4 mg in patients when recorded on a per-attempt basis. The most common but infrequent and mild side effect of nausea decreases with use. The phase III trials of apomorphine SL show that there is a clinically important restoration of erectile function from this new formulation of apomorphine. It has a rapid and safe effect through action in the central nervous system. Apomorphine SL brings a new choice to the management of ED that will further bene®t the millions of couples affected.

A co-ordinated series of vascular events underlie the generation of a penile erection. The control and regulation of this simple event is, in fact, a complex of interactions occurring at multiple levels. Many of these individual pathways and responses have been studied extensively. The understanding of the necessity for the integration between the individual pathways into a complex of series and parallel coupled mechanisms provides a rationale for the development of a framework of multiple and overlapping systems. This paper sets out some of the principles of integrated and balanced control of vasodilation and vasoconstriction in the penis. In addition, the role of growth induction and regression and the importance of time as a factor in studying penile structure and function is discussed.