If you have an erection that lasts for more than 4 hours, you should go to the nearest hospital emergency department. The major circulating metabolite results from N-desmethylation of sildenafil, and is itself further metabolized. Population pharmacokinetic data from patients in clinical trials also indicated a reduction in sildenafil clearance when it was co-administered with CYP3A4 inhibitors such as ketoconazole, erythromycin, or cimetidine [see Dosage and Administration 2. For treatment of pulmonary arterial hypertension: For oral dosage forms suspension or tablets : Adults—20 milligrams mg 3 times a day. Cialis vs. 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. Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient.AdWith RexMD you’re saving time and money with our Viagra delivery. Get started now. Reliable E.D. meds prescribed by real doctors. Get your free & private online visit test1.ru has been visited by 10K+ users in the past monthFree Shipping · Discreet Packaging · Real Doctors · Personalized PlanTypes: Premature Ejaculation · Sexual Health · Privacy Policy. Who may not be able to take sildenafil. Sildenafil is not suitable for some people. To make sure it’s safe for you, speak to your doctor or pharmacist before taking sildenafil if you: have ever had an allergic reaction to sildenafil or any other medicine. have recently had a stroke, heart attack or a heart problem – your doctor should. Sildenafil (Viagra, Revatio) is a moderately priced drug used to treat erection problems in test1.ru is also used to treat pulmonary arterial hypertension, a serious heart and lung test1.ru drug is more popular than comparable drugs. It is available in generic and brand versions. Generic sildenafil is covered by most Medicare and insurance plans, but .