The first study examined the effects of increasing doses of sildenafil on the results of several visual function tests. A double-blind, placebo-controlled, crossover, Phase II study assessed the acute effects (1 to 24 hours) of sildenafil (50 to 200 mg) in 16 healthy male volunteers. Sildenafil did not produce clinically significant changes in visual acuity, […]
Cognizant of the preclinical data, substantial efforts were made to investigate the visual effects of sildenafil during clinical development. A number of Phase II and III studies were carried out to determine the safety of sildenafil in relation to the retina and visual function. Much of the data, with complete study descriptions, will appear in […]
Early in preclinical development, it was found that sildenafil inhibits retinal PDE6 enzymes with an IC50 of 27-58 nM. Although this was substantially less than its effect on the intended target, PDE5 (IC50 3.9 nM), it led to the evaluation of safety of high doses of sildenafil on retinal histopathology in rats and dogs and […]
Viagra (sildenafil citrate) is the first of a new class of orally effective treatments for erectile dysfunction. It potently inhibits cGMP-specific phosphodiesterase type 5 (PDE5) (Fig 1), found in high concentrations in the smooth-muscle cells of corpus cavernosum and in lesser concentrations in blood vessels of the systemic circulation. Because of its ability to act […]
To date, sildenafil citrate (Viagra) gives every evidence of being a safe drug for the eye despite a series of expressed concerns. A review of how its ocular safety profile has been identified offers insights into the strengths and weaknesses of present systems and resources for judging the ocular safety of Viagra or, for that […]
Impotence remedies Viagra, Cialis and Levitra have been associated with a sudden loss of hearing in some patients, the FDA said today. Whoa! Wasn’t it worrying enough when the agency warned two years ago that drugs have been associated with sudden loss of vision in some patients? Somebody at FDA caught wind of a case […]
If the entertainment had been as good as the food, I’d have little trouble recommending Stage West dinner theatre’s latest production, Viagra Falls. But as it stands, there are few highlights in this 90-minute, three-man show that runs until Nov. 16. The brightest of these is former Love Boat actor Bernie Kopell, whose years of […]