Pharm

Guanabenz

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Guanabenz, Wytensin, Guanfacine, Tenex

  • Mechanism
  1. See Alpha Adrenergic Central Agonist
  2. See Alpha Adrenergic Receptor
  3. Central Acting Adrenergic Agonists
    1. Activate alpha-2 receptors that inhibit CNS sympathetic signals
    2. Results in increased parasympathetic effects and side effects
  4. Peripheral Adrenergic Nerve terminal activity
    1. Depletes Norepinephrine stores
  • Pharmacokinetics
  1. Renal and hepatic clearance
  2. Adjust dose for renal or hepatic Impairment
  • Dosing
  • Guanabenz (Wytensin)
  1. Adult: 2 to 4 mg orally twice daily (up to 32 mg twice daily)
  2. Child (over age 12): 0.25 to 1 mg orally twice daily (up to 2 to 12 mg orally twice daily)
  • Dosing
  • Guanfacine (Tenex)
  1. Adults and children >12 years
    1. Start 1 mg orally at bedtime
    2. Most effective dose is 1 mg
      1. May increase to 2-3 mg at bedtime after 3-4 weeks (as needed)
      2. Maximum: 3 mg/day
  • Adverse Effects
  1. Dry Mouth
  2. Sedation
  3. Rebound Hypertension
    1. Less than with Clonidine
  • Drug Interactions
  1. Thiazide Diuretics
    1. Increased antihypertensive effect (Hypotension risk)
  • References
  1. Olson (2020) Clinical Pharmacology, MedMaster, Miami, p. 64-5
  2. Hamilton (2010) Tarascon Pocket Pharmacopeia, Jones and Bartlett, p. 76