The major circulating metabolite results from N-desmethylation of sildenafil, and is itself further metabolized. VIAGRA sildenafil citrate is supplied as blue, film-coated, rounded-diamond-shaped tablets containing sildenafil citrate equivalent to the nominally indicated amount of sildenafil and debossed on the obverse and reverse sides as follows: 25 mg. If you have an erection that lasts more than 4 hours, get medical help right away. This matters, because fake Viagra can be cut with everything from printer ink to speed. Sudden vision loss in one or both eyes can be a sign of a serious eye problem called non-arteritic anterior ischemic optic neuropathy NAION.Some over-the-counter (OTC) supplements may help with erectile dysfunction, such as L-arginine in combination with pycnogenol, Korean red ginseng (also called panax . Yes, penile pumps (also known as ED pumps) are over-the-counter devices that work to treat erectile dysfunction, similar to Viagra. Viagra (sildenafil) is usually the first-line . Muse, Caverject, and Trimix can be good substitutes for Viagra (sildenafil). But they require insertion or injection into the penis. There’s some evidence that L-arginine might help .