Viagra Dosage
As a drug, Viagra has been around for about 15 years. It is based on sildenafil citrate, which is contained in tablets. This is a prescription medicine intended for treatment of sexual dysfunction in men, and it should be administered as recommended by a qualified doctor. The drug is available in blue film-coated tablets, which differ in size: a tablet may contain 25mg, 50mg and 100mg of sildenafil citrate.
Such differentiation is dictated by people's varied individual capacity and tolerability. Some people can use it safely for along time, while others experience nasty side effects even at first administration. Besides, Viagra can be dangerous for those suffering chronic cardiovascular and some metabolic diseases. The drug has several major contraindications, and it is incompatible with a number of other medicines. These are just a few reasons why the drug should not be used without a professional consultation.
In any event, dosage should be adjusted prior to taking Viagra, and with the help of a qualified physician. The dose, which your doctor will recommend, will depend on your age, the severity of impotence, its exact cause and your general condition. Commonly, a 50-mg dose is recommended as a starter. Usually, it takes a few days to see if it works well and if any adverse side effects occur.
Depending on how effective it is, your physician may instruct you to stick to your current dose, increase or decrease it. The drug's effect depends on plasma concentrations, which should not exceed admissible levels. Plasma levels of sildenafil depend on age and the functioning of liver and kidneys. It has been estimated that elderly people (over 60 years old) have lower clearance, which may cause plasma levels to increase by 40%. Severe hepatic or renal impairment may contribute to an one-hundred-per-cent increase in plasma concentration. Therefore, Viagra is contraindicated to people suffering severe cases of renal or hepatic impairment. For people dealing with mild or moderate cases of these disorders, the starting dose should be 25mg.
Plasma concentrations may soar if Viagra is used concomitantly with other potent enzyme inhibitors, as well as drugs used for treatment of cardiac diseases (nitrates and nitrites), alpha-blockers or other ED drugs. Concomitant use of sildenafil with the abovementioned medicines potentiates its hypotensive effect and can lead to a sudden and rapid blood pressure decrease. This, in turn, may impact blood flow to vital organs. Viagra is administered once per 24 hours, or less frequently (never more!) The drug's effect becomes observable 30 to 60 minutes after administration.