Viagra is suggested to be taken 1 hour before the sexual activity. However, it can be consumed from 4 hours to 0.5 hours before sex without any problem. The recommended dose is 50 mg for most of the people. Depending upon the tolerance capability and effectiveness, dose of Viagra can be increased up to 100 mg and can be decreased up 25 mg. Viagra is suggested to be taken once a day. Viagra should not be taken empty stomach.
As we have already discussed that dose and effectiveness of Viagra depends upon tolerance where age plays an important role. Here are given certain factors that are associated with increased plasma levels of Viagra;
Status
For age >65-
Hepatic impairment
Severe renal impairment
Concomitant use of potent cytochrome P450
3A4 inhibitors
Saquinavir |
plasma level
40% increase in AUC
80%
100%
182%
210% |
Higher the plasma levels, higher will be the efficacy and incidence of adverse events, so, an initial dose of 25 mg should be considered in these patients.
Recent studies done with healthy, non-HIV infected volunteers demonstrated increased systemic levels of Viagra (11 fold increase of AUC) by Ritonavir that led to the fact that one should not exceed a maximum single dose of 25 mg of VIAGRA in a 48 hour period.
Viagra is revealed to intensify the hypotensive effects of nitrates and so people who are on nitric oxide donors or nitrates are recommended not to take Viagra.
Viagra Over dosage
A higher dose up to 800 mg is shown to have adverse events like that of lower doses, though at increased incidence rates. Standard supportive measures are suggested if higher dose is taken. Dialysis is not a good idea to quicken clearance as Viagra tend to bind plasma proteins and not eliminated in the urine. |
