Systemic and metabolic effects of PDE5-inhibitor drugs

Phosphodiesterase type-5 inhibitor (PDE5-i) drugs were first marketed in 1998 (sildenafil) for 'on-demand' treatment of male erectile dysfunction (ED) of any origin. They selectively inhibit intrapenile PDE5 isoen-zyme which in turn increases intracellular cyclic guanosine monophosphate levels, thus resulting in prolonged relaxation of cavernosum smooth muscle cells and facilitating the erectile proce-ss. Since 2003, two new molecules (tadalafil and vardenafil) have been introduced, resulting in greater interest in these compounds and leading patients to ask for more prescriptions from their doctors. The vast use of PDE5-i in diabetic and cardiovascular ED patients led rese-archers to investigate their possible extra sexual effects. Several studies investigating their effects on endothelium, coronary and pulmonary circulation, in-ferior oesophageal sphincter and kidney functions have appeared and, finally, sildenafil was approved for the treatment of pulmonary arterial hyperte-n-sion. Recent animal studies highlighted a possible interaction between chronic PDE5 inhibition and glucose homeostasis which occurs through a marked improve-ment of high fat diet induced insulin resistance. If this data is extended to humans, a new scenario will be opened for the chronic use of PDE5-i for sexual rehabili-tation along with cardiovascular and metabolic benefits. (C) 2010 Baishideng. All rights reserved.