Never take 2 doses at the same time. Pediatric Patients: Increased mortality with increasing sildenafil dose was observed in a clinical trial of pediatric patients with PAH. The body takes longer to absorb it after a high-fat meal or alcohol. Do not take a double dose to make up for a missed one. Some examples of nitrates are nitroglycerin Nitro-Dur, Nitrostat, others , isosorbide mononitrate Monoket and isosorbide dinitrate Bidil. If you have certain health conditions or are taking certain medications, your doctor may tell you to take sildenafil less often. · Maximum dose: 20 mg orally three times a day. Injection: Initial dose: or 10 mg IV bolus three times a day. Comments: No greater efficacy was achieved with oral doses higher than the maximum recommended dose. A 10 mg injection dose is predicted to provide pharmacological effect equivalent to the 20 mg oral dose.  · Compare prescription drug prices and find coupons at more than 70, US pharmacies. Save up to 80% instantly!  · 97% average discount Depression 86% average discount Hypertension 74% average discount Urinary Tract Infection 67% average discount Based on the average .