III. Mechanism

  1. See Alpha Adrenergic Central Agonist
  2. See Alpha Adrenergic Receptor
  3. Central Acting Adrenergic Agonists
    1. Activates alpha-2 receptors that inhibit CNS preganglionic sympathetic signals, lowering Blood Pressure
    2. Results in increased parasympathetic effects and side effects (e.g. sedation)
  4. Peripheral Adrenergic Nerve terminal activity
    1. Depletes Norepinephrine stores

IV. Pharmacokinetics

  1. Renal and Hepatic Clearance
  2. Adjust dose for renal or hepatic Impairment

V. 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)

VI. Dosing: Guanfacine (Tenex)

  1. Adults and children age >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

VII. Adverse Effects

  1. Dry Mouth
  2. Sedation
  3. Rebound Hypertension
    1. Less than with Clonidine

VIII. Drug Interactions

  1. Thiazide Diuretics
    1. Increased antihypertensive effect (Hypotension risk)

IX. References

  1. Olson (2020) Clinical Pharmacology, MedMaster, Miami, p. 64-5
  2. Hamilton (2010) Tarascon Pocket Pharmacopeia, Jones and Bartlett, p. 76

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Related Studies

Cost: Medications

guanfacine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
GUANFACINE 1 MG TABLET Generic $0.39 each
GUANFACINE 2 MG TABLET Generic $0.56 each
GUANFACINE HCL ER 1 MG TABLET Generic $0.21 each
GUANFACINE HCL ER 2 MG TABLET Generic $0.22 each
GUANFACINE HCL ER 3 MG TABLET Generic $0.22 each
GUANFACINE HCL ER 4 MG TABLET Generic $0.24 each