Phosphodiesterase 5 Inhibitors
Overview
PDE 5 inhibitors have traditionally been used to treat patients with ED; several compounds are already approved and marketed for that indication. Tadalafil (Eli Lilly cos’s Cialis) is the first PDE 5 inhibitor under investigation for the treatment of benign prostatic hyperplasia. Tadalafil has great potential as a supplemental treatment for dynamic benign prostatic hyperplasia, a role that is not filled by any other drug.
Mechanism Of Action
Researchers propose that PDE 5 inhibitors have an effect on the contractibility of prostate smooth muscle. An examination of their effect on rapid ejaculation shows that these agents can improve the symptoms of benign prostatic hyperplasia by reducing the contractile response of prostatic and urethral tissues. A bovine model has demonstrated that decreased blood flow to the prostate causes localized muscle contraction; treatment with a PDE 5 inhibitor relaxed muscles in the ischemic tissues. Further research is required to fully understand the mechanism of action of PDE 5 inhibitors on the prostate gland.
Tadalafil
Icos’s tadalafil is currently in Phase II development for the treatment of benign prostatic hyperplasia. The company initiated studies in May 2004, and by November 2004, clinical trials were under way. Icos stated that its research suggests that tadalafil can relax prostatic smooth muscle, thereby reducing obstructive symptoms associated with benign prostatic hyperplasia.
Posted in: Benign Prostatic Hyperplasia