They enhance the effects of a chemical the body makes that relaxes muscles in the penis, called nitric oxide. Often, these are prescribed for chest pain called angina. It continues to work for up to 4 hours, although its action is usually less after 2 hours. Store mixed oral liquid in the refrigerator. Keep from freezing. · 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. Best prices for generic viagra on the Internet! The safest way is to ask your physician to try an alternate prescription. Sildenafil 50mg Tablets are designed for men who are suffering from Erectile Dysfunction problems. Recall that it is necessary to strictly observe the rules for storing drugs in the refrigerator; some drugs cannot be frozen. DRUG_DESCRPTION Compare DRUG_NAME prices and find coupons that could save you up to 80% instantly at pharmacies near you such as CVS, Walgreens, Walmart, and .