In a study of healthy male volunteers, co-administration of sildenafil at steady state 80 mg t. The amount of medicine that you take depends on the strength of the medicine. To use the oral liquid: Shake the bottle well for at least 10 seconds before each use. Seven of these companies are based in India. That means you can have erections whenever you want or need them. This medicine is available only with your doctor’s prescription. Cialis stays in your system for up to 36 hours, and you can take it daily.Key facts. Sildenafil (Viagra) is a medicine used to treat erectile dysfunction (ED, also called impotence). Sildenafil works by helping to relax the blood vessels in the penis, allowing more blood to flow in and cause an erection. You should take sildenafil about an hour before planned sexual activity, so it has time to work. The list below does not include all possible drug interactions with Sildenafil (Viagra). Please note that only the generic name of each medication is listed below. More on Sildenafil (Viagra) interactions. Cialis is a brand-name medication used to treat erectile dysfunction. You can look into a generic form and other ways to save money. VIAGRA contains sildenafil, which is the same medicine found in another drug called REVATIO. REVATIO is used to treat a rare disease called pulmonary arterial hypertension (PAH). VIAGRA should not be used with REVATIO or with other PAH treatments containing sildenafil or any other PDE5 inhibitors (such as Adcirca [tadalafil]).
