CGMP-specific Phosphodiesterase Type 5 - PDE5-inhibiting Drugs

PDE5-inhibiting Drugs

There are now three oral erectile dysfunction (ED) drugs: Viagra (sildenafil) by Pfizer, Levitra (vardenafil) by Bayer Pharmaceutical and Glaxo-Smith-Kline-Beecham/Schering Plough, and Cialis (tadalafil) by Lilly-ICOS.

For all practical purposes, these drugs including Viagra, Levitra, and Cialis are the first line of oral treatment for males with erectile dysfunction. In certain circumstances in which the males are young, no comorbidities are recognized, and laboratory tests are normal one should look for the etiology of their erectile dysfunction before instituting treatment since the disease process may be more serious than the symptoms, i.e., the ED itself. In some cases, treatment of the primary disease may in fact resolve the sexual dysfunction. However, most men have a cause for their ED as noted by the history and physical examination and the laboratory tests and PDE-5 inhibitors are the first line of choice.

Particular caution should be used when prescribing PDE5 inhibitors for erectile dysfunction for patients receiving protease inhibitors, including Reyataz. Coadministration of a protease inhibitor with a PDE5 inhibitor is expected to substantially increase the PDE5 inhibitor concentration and may result in an increase in PDE5 inhibitor-associated adverse events, including hypotension, visual changes, and priapism.

PDE5-inhibiting drugs are very effective. PDE5 inhibitor drugs appear to work in men regardless of why they have erectile dysfunction — including vascular disease, nerve problems, and even psychological causes. PDE5-inhibiting drugs can cause a number of minor side-effects, including headache, lightheadedness, dizziness, flushing, nasal congestion, and changes in vision. In 2011, the Food and Drug Administration (FDA) issued additional guidance on regulations related to CGMP manufacture and packaging.