Phosphodiesterase type 5 inhibitors for erectile dysfunction.
The cyclic nucleotide signalling pathway mediates the smooth-muscle relaxing effects of nitric oxide necessary for normal erectile function. Down-regulation of this pathway is central to the pathophysiology of many forms of erectile dysfunction (ED), which is often associated with other chronic diseases (e.g. hypertension, type 2 diabetes mellitus) and treatments (e.g. certain drugs, radical prostatectomy). Conversely, selective inhibition of the enzyme that catalyses the degradation of cGMP (phosphodiesterase type 5, PDE-5) promotes erectile responses to sexual stimulation. The successful launch and commercialization of the selective PDE5 inhibitor (PDE5I) sildenafil transformed the treatment of ED, not only by providing an effective, well tolerated oral ED therapy, but also by fostering greater candour about the problem among men. Sildenafil is highly effective in promoting erectile responses across a wide spectrum of severity and causes of ED, including patients with ED that is often refractory to treatment. The recent advent of vardenafil, which has the highest in vitro potency of all available PDE5Is, and tadalafil, which has a prolonged half-life that may enable couples to have sexual activity with less planning, represent further advances. Other PDE5Is offering further potential improvements are under active investigation.
Carson
Culley C
CC
Department of Surgery, Division of Urology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. Carson@med.unc.edu
Lue
Tom F
TF
D015106:3',5'-Cyclic-GMP Phosphodiesterases; D000465:Algorithms; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D004347:Drug Interactions; D007172:Erectile Dysfunction / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology; D005544:Forecasting; D006801:Humans; D008297:Male; D010410:Penile Erection / Q000187:drug effects* / Q000502:physiology; D010726:Phosphodiesterase Inhibitors / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*; D010727:Phosphoric Diester Hydrolases; D011471:Prostatic Neoplasms / Q000188:drug therapy; D016896:Treatment Outcome
D010726:Phosphodiesterase Inhibitors; D010727:Phosphoric Diester Hydrolases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517381:PDE5A protein, human