VIAGRA (Sildenadil Citrate) is assessed for its effect on the ability of men with erectile dysfunction (ED) to engage in sexual activity and in many cases specifically on the ability to achieve and maintain an erection sufficient for satisfactory sexual activity. Sildenafil Citrate successfully acts by blocking a certain enzyme or phosphodiesterase-PDE5 in the body. This medicine or sildenafil citrate is prepares as blue, film-coated rounded-diamond-shaped tablets equal to 25 mg, 50 mg and 100 mg of sildenafil for oral use. It also increases the blood pressure lowering effects of nitrates (for example, isosorbide dinitrate) that are used mainly for treating angina. You can buy this effective drug here at very low prices.