If you are taking sildenafil to treat PAH, you will probably take sildenafil three times a day with or without food. What special precautions should I follow? This is consistent with ritonavir’s marked effects on a broad range of P substrates. VIAGRA improved these aspects of sexual function: frequency, firmness and maintenance of erections; frequency of orgasm; frequency and level of desire; frequency, satisfaction and enjoyment of intercourse; and overall relationship satisfaction. Some platforms have a digital pharmacy that ships the medication to your home, while others send an electronic prescription to your local pharmacy. The major circulating metabolite results from N-desmethylation of sildenafil, and is itself further metabolized.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. $12 View other PDE5 Inhibitors Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in men. It is also used to treat pulmonary arterial hypertension, a serious heart and lung condition. This drug is more popular than comparable drugs. It is available in generic and brand versions.  · The Answers You Need. Expert-reviewed resources to help you navigate your health journey, from A to Z and everything in between. Compare prescription drug .