II. Dosing
- Standard Dose: 5-20 mg up to once daily, 1 hour prior to intercourse
- Adjusted maximum dosing
- Hepatic insufficiency: 10 mg
- Age over 65 years: 5 mg
III. Pharmacokinetics
- Onset 30-60 minutes
- Duration: 4-5 hours
IV. Contraindications
- See Phosphodiesterase Inhibitors (PDE5 Inhibitors)
- Men using nitrates (causes profound Hypotension)
- Men using alpha blockers (e.g. Hytrin for BPH)
V. Mechanism
VI. Drug Interactions
- See Phosphodiesterase Inhibitors (PDE5 Inhibitors)
- Profound Vasodilitation and Hypotension with Nitroglycerin and alpha blockers such as Prazosin (Avoid)
- Avoid Nitrates within 24 hours of Verdenadil (Levitra)
- Cytochrome P3A4 related interactions (Cimetidine, systemic Antifungals, Protease Inhibitors and Macrolides
VII. Adverse Effects: Viagra (but most apply to the PDE5 Class as a whole)
- See Phosphodiesterase Inhibitors (PDE5 Inhibitors)
- Hypotensive effect for men on Nitrates (Avoid)
- Vision effects (color Vision, Vision Loss)
- Sensorineural Hearing Loss
- Mild Headache