If you are taking sildenafil to treat PAH, you will probably take sildenafil three times a day with or without food. Do not take more or less of it or take it more often than prescribed by your doctor. Tell your doctor if sildenafil is not working well or if you are experiencing side effects. The primary measure in the principal studies was a sexual function questionnaire the International Index of Erectile Function – IIEF administered during a 4-week treatment-free run-in period, at baseline, at follow-up visits, and at the end of double-blind, placebo-controlled, at-home treatment. Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. This is consistent with ritonavir’s marked effects on a broad range of P substrates. One-third to one-half of the subjects in these studies reported successful intercourse at least once during a 4-week, treatment-free run-in period.AdRx. Encuentra increíbles ofertas y consigue cupones para ahorrar aún más.1M+ visitors in the past month. Here are answers to some frequently asked questions about drug cost and Viagra. How . Does the price of sildenafil vary based on strength or what it’s prescribed for? The price you’ll pay for sildenafil may vary based on the strength and form of the drug your doctor prescribes for.