II. Indications

  1. Psychogenic Impotence
  2. Neurogenic Impotence
  3. Vasculogenic Impotence

III. Pharmacokinetics

  1. Onset within 30 to 60 minutes
  2. Duration as long as 36 hours
    1. Contrast with 4 hours with Viagra
    2. Prolonged effect also leads to prolonged side effects

IV. Dosing

  1. Start 20 mg PO 1 hour before intercourse
    1. Do not take more than once per 2 days
    2. Most insurance limits to 6 per month
  2. Indications to start with half dosing (10 mg)
    1. Age over 65 years
    2. Hepatic Impairment
    3. Renal Impairment
    4. Concurrent use of Cytochrome P3A4 inhibitor below

V. Contraindications

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

VII. 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 48 hours of Tadalafil (Cialis)
  3. Cytochrome P3A4 related interactions (Cimetidine, systemic Antifungals, Protease Inhibitors and Macrolides

VIII. Adverse Effects: Viagra (but most apply to the PDE5 Inhibitor 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 (21%)

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Cost: Medications

cialis (on 5/18/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
CIALIS 5 MG TABLET Generic $0.13 each
tadalafil (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
TADALAFIL 10 MG TABLET Generic $0.35 each
TADALAFIL 2.5 MG TABLET Generic $0.17 each
TADALAFIL 20 MG TABLET Generic $0.26 each
TADALAFIL 5 MG TABLET Generic $0.13 each