NEURAL AND PHARMACOLOGICAL DETERMINANTS OF ERECTION

An integrative analysis of the determinants of erection will reveal th at almost all the common actions of smooth muscle and endothelial cell s found in normal vascular biology (NVB), and some neural mechanisms, have roles in supporting erectile function. Many of these cellular mec hanisms have been harnessed to create drugs that are or will be used t o treat erectile dysfunction. Without standard diagnostic or therapeut ic methods, or classifications, it is difficult to compare drugs, and difficult to target the specific deficiencies causing erectile dysfunc tion. A classification is suggested here that hinges on the identifica tion of two main characteristics. Firstly, there is a fundamental diff erence between initiating an erection (initiators) and facilitating or enhancing an erection already initiated by other processes (condition ers), and secondly, there are different implications for adverse effec ts and drug delivery that arise from targeting central nervous system or peripheral systemic processes. These properties suggest a classific ation of treatments based on a two-by-two matrix. Within each class dr ugs will be more equivalent enabling better comparisons and more stand ardized evaluative strategies. By observing the characteristics of pat ients benefiting from drugs of an identified class it may be possible to develop a physiologically based classification of diagnoses. There may be logical combinations of drugs that will be assembled in clinica l practice, taking suitable agents from one of two or more classes. No single mechanism will stand out as overwhelming and no single drug wi ll treat all erectile dysfunction.