Therapeutic Classification: erectile dysfunction agents, vasodilators
Pharmacologic Classification: phosphodiesterase type 5 inhibitors
Absorption: Rapidly absorbed (41%) after oral administration; IV administration results in complete bioavailability.
Distribution: Widely distributed to tissues; negligible amount in semen.
Protein Binding: 96%.
Metabolism/Excretion: Primarily metabolized by the liver via the CYP3A4 isoenzyme; one metabolite is active and accounts for 20% or more of drug effect. Metabolites excreted mostly (80%) in feces; 13% excreted in urine.
Half-Life: 4 hr (for sildenafil and active metabolite).
( vasodilation, ability to produce erection)
| ROUTE | ONSET | PEAK | DURATION |
|---|
| PO | within 1 hr | 30–120 min | up to 4 hr |
Erectile Dysfunction
- PO (Adults ): Viagra: 50 mg taken 1 hr before sexual activity (range 25–100 mg taken 30 min–4 hr before sexual activity); not more than once daily; Concurrent use of Viagra with alpha-blocker antihypertensives: Do not use 50–100 mg dose within 4 hr of alpha blocker; 25-mg dose may be taken anytime.
- PO Geriatric Patients ≥65 yr or with concurrent enzyme inhibitors): Viagra: 25 mg taken 1 hr before sexual activity (range 25–100 mg taken 30 min–4 hr before sexual activity); not more than once daily.
Hepatic/Renal Impairment
- PO (Adults ): Viagra: 25 mg taken 1 hr before sexual activity (range 25–100 mg taken 30 min–4 hr before sexual activity); not more than once daily.
Pulmonary Arterial Hypertension
- IV therapy is indicated for patients unable to take PO therapy
- PO (Adults ): Revatio: 20 mg 3 times daily; may ↑ in 20-mg increments to 80 mg 3 times daily based on clinical response and tolerability.
- PO (Children ≥1 yr and >45 kg): Revatio: 20 mg 3 times daily; may ↑ to 40 mg 3 times daily based on clinical response and tolerability.
- PO (Children ≥1 yr and 21–45 kg): Revatio: 20 mg 3 times daily.
- PO (Children ≥1 yr and ≤20 kg): Revatio: 10 mg 3 times daily.
- IV (Adults ): Revatio: 10 mg 3 times daily.
