Therapeutic Classification:erectile dysfunction agents
Pharmacologic Classification: phosphodiesterase type 5 inhibitors
Absorption: 15% absorbed following oral administration; absorption is rapid.
Distribution: Extensive tissue distribution; penetrates semen.
Protein Binding: 95%.
Metabolism/Excretion: Mostly metabolized by the liver via the CYP3A4 isoenzyme and to a lesser extent by the CYP2C isoenzyme. M1 metabolite has anti-erectile dysfunction activity. Parent drug and metabolites are mostly excreted in feces. 2–6% renally eliminated.
Half-life: 4–6 hr.
Derm: flushing.
EENT: HEARING LOSS, rhinitis, sinusitis, VISION LOSS.
GI: dyspepsia, nausea.
GU: priapism.
Neuro: headache, amnesia, dizziness.
Misc: flu syndrome.
The tablets and orally disintegrating tablets are not interchangeable; the orally disintegrating tablets provide a higher level of systemic exposure compared to the tablets
Tablets
- PO (Adults): 10 mg taken 1 hr prior to sexual activity (range 5–20 mg; not to exceed one dose/24 hr); Concurrent use of cobicistat or ritonavir: single dose should not exceed 2.5 mg in any 72-hr period; Concurrent use of atazanavir, clarithromycin, ketoconazole 400 mg daily, or itraconazole 400 mg daily: single dose should not exceed 2.5 mg/24 hr; Concurrent use of ketoconazole 200 mg daily, itraconazole 200 mg daily, or erythromycin: single dose should not exceed 5 mg/24 hr; Concurrent use of stable alpha-blocker therapy (not on potent CYP3A4 inhibitor): 5 mg initial dose; titrate as tolerated; Concurrent use of stable alpha-blocker and potent CYP3A4 inhibitor therapy: 2.5 mg initial dose; titrate as tolerated.
- PO (Geriatric Patients ≥65 yr): 5 mg initial dose; titrate as tolerated.
Hepatic Impairment
- PO (Adults): Moderate hepatic impairment: May start with 5 mg dose (not to exceed 10 mg).
Orally Disintegrating Tablets
- PO (Adults): 10 mg taken 1 hr prior to sexual activity (not to exceed one dose/24 hr).
