The pharmacokinetics of sildenafil are dose-proportional over the recommended dose range. Follow the manufacturer’s directions to use and clean the oral syringe. Figure 6 shows that regardless of the baseline levels of function, subsequent function in patients treated with VIAGRA was better than that seen in patients treated with placebo. However, if you take sildenafil with a high-fat meal, it will take longer for the medication to start to work. A starting oral dose of 25 mg should be considered in those patients [see Dosage and Administration 2. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine. During 3 to 6 months of double-blind treatment or longer-term 1 year , open-label studies, few patients withdrew from active treatment for any reason, including lack of effectiveness.Generic medications work just like brand-name equals, providing the same quality and performance for less money. In fact, the U.S. Food and Drug Administration requires . VIAGRA is supplied as blue, film-coated, rounded-diamond-shaped tablets containing sildenafil citrate equivalent to 25 mg, 50 mg, or mg of sildenafil. Tablets are debossed with PFIZER on one side and VGR25, VGR50 or VGR on the other to indicate the dosage strengths. Close. Sildenafil oral tablet is available as a brand-name drug and as a generic drug. Brand names: Viagra, Revatio. Sildenafil comes in three forms: an oral tablet, an oral suspension (liquid), and an.