Temporary loss of vision and increased sensitivity to light are among the eye disorders that have been reported with sildenafil (Viagra) since marketing. Other effects include increased intra-ocular pressure, green/blue tinging of vision and blurred vision. Some of these disorders may be caused by an exaggerated physiological change due to weak inhibitory effects of sildenafil on the isoenzyme phosphodiesterase type 6 (PDE6) in the retina, say the Committee on Safety of Medicines and the Medicines Control Agency in the latest issue of Current Problems in Pharmacovigilance (1999;25:16).
There have also been reports of prolonged erection and priapism after use of sildenafil.
Discussing possible cardiovascular adverse reactions to the drug, the CSM and MCA say that there have been reports of serious reactions, including myocardial infarction, sudden cardiac death, ventricular arrhythmia and hypertension. Most occurred in men with pre-existing cardiovascular risk factors. "Currently it is not clear whether these events are related directly to sildenafil, to sexual activity or to underlying undiagnosed cardiovascular disease," they comment.