Viagra Clinical Pharmacology

After either articulate or intravenous administration, sildenafil is excreted as metabolites predominantly in the carrion (approximately 80% of administered articulate dose) and to a bottom admeasurement in the urine (approximately 13% of the administered articulate dose). Similar ethics for pharmacokinetic ambit were apparent in accustomed volunteers and in the accommodating population, application a citizenry pharmacokinetic approach.
Pharmacokinetics in Special Populations
Geriatrics: Advantageous aged volunteers (65 years or over) had a bargain approval of sildenafil, with chargeless claret concentrations about 40% greater than those apparent in advantageous adolescent volunteers (18-45 years).
Renal Insufficiency: In volunteers with balmy (CLcr=50-80 mL/min) and abstinent (CLcr=30-49 mL/min) renal impairment, the pharmacokinetics of a individual articulate dosage of VIAGRA (50 mg) were not altered. In volunteers with astringent (CLcr= < 30 mL/min) renal impairment, sildenafil approval was reduced, consistent in about acceleration of AUC and Cmax compared to age-matched volunteers with no renal impairment.
Hepatic Insufficiency: In volunteers with hepatic cirrhosis (Child-Pugh A and B), sildenafil approval was reduced, consistent in increases in AUC (84%) and Cmax (47%) compared to age-matched volunteers with no hepatic impairment.
Therefore, age > 65, hepatic crime and astringent renal crime are associated with added claret levels of sildenafil. A starting articulate dosage of 25 mg should be advised in those patients (see DOSAGE AND ADMINISTRATION).
Viagra Pharmacodynamics
Effects of VIAGRA on Arrect Response: In eight double-blind, placebo-controlled crossover studies of patients with either amoebic or analytic arrect dysfunction, animal dispatch resulted in bigger erections, as adjourned by an cold altitude of acerbity and continuance of erections (RigiScan), afterwards VIAGRA administering compared with placebo. A lot of studies adjourned the ability of VIAGRA about 60 account column dose. The arrect response, as adjourned by RigiScan®, about added with accretion sildenafil dosage and claret concentration. The time advance of aftereffect was advised in one study, assuming an aftereffect for up to 4 hours but the acknowledgment was beneath compared to 2 hours.
Effects of VIAGRA on Claret Pressure: Individual articulate doses of sildenafil (100 mg) administered to advantageous volunteers produced decreases in collapsed claret burden (mean best abatement in systolic/diastolic claret burden of 8.4/5.5 mmHg). The abatement in claret burden was a lot of notable about 1-2 hours afterwards dosing, and was not altered than placebo at 8 hours. Similar furnishings on claret burden were acclaimed with 25 mg, 50 mg and 100 mg of VIAGRA, accordingly the furnishings are not accompanying to dosage or claret levels aural this dosage range. Larger furnishings were recorded a part of patients accepting accessory nitrates.