The body takes longer to absorb it after a high-fat meal or alcohol. Sildenafil Viagra is used to treat erectile dysfunction impotence; inability to get or keep an erection in men. Pfizer obtained the patent in after applying four years earlier. Medicines that block an enzyme called CYP3A4. John’s wort. Sexual activity may be a strain on your heart, especially if you have heart disease.According to price-comparison site test1.ru, generic Revatio will cost you as little as $ per pill, depending on where you fill your prescription. That’s compared with more than $50 per.  · The highest recommended Viagra dose for treating erectile dysfunction (ED) is mg per day, according to the drug’s manufacturer. Doses of mg or mg would be considered off-label use. Prices for Viagra can vary considerably among pharmacies. However, it can cost more than $ for 10 of the milligram (mg) tablets. Generic versions will generally cost less than the branded.