II. Dosing

  1. Standard Dose: 5-20 mg up to once daily, 1 hour prior to intercourse
  2. Adjusted maximum dosing
    1. Hepatic insufficiency: 10 mg
    2. Age over 65 years: 5 mg

III. Pharmacokinetics

  1. Onset 30-60 minutes
  2. Duration: 4-5 hours

IV. Contraindications

  1. See Phosphodiesterase Inhibitors (PDE5 Inhibitors)
  2. Men using nitrates (causes profound Hypotension)
  3. Men using alpha blockers (e.g. Hytrin for BPH)

VI. Drug Interactions

  1. See Phosphodiesterase Inhibitors (PDE5 Inhibitors)
  2. Profound Vasodilitation and Hypotension with Nitroglycerin and alpha blockers such as Prazosin (Avoid)
    1. Avoid Nitrates within 24 hours of Verdenadil (Levitra)
  3. 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)

  1. See Phosphodiesterase Inhibitors (PDE5 Inhibitors)
  2. Hypotensive effect for men on Nitrates (Avoid)
  3. Vision effects (color Vision, Vision Loss)
  4. Sensorineural Hearing Loss
  5. Mild Headache

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