II. Indications
III. Mechanism
- See Alpha Adrenergic Central Agonist
- See Alpha Adrenergic Receptor
- Central Acting Adrenergic Agonists
- Activates alpha-2 receptors that inhibit CNS preganglionic sympathetic signals, lowering Blood Pressure
- Results in increased parasympathetic effects and side effects (e.g. sedation)
- Peripheral Adrenergic Nerve terminal activity
- Depletes Norepinephrine stores
IV. Pharmacokinetics
- Renal and Hepatic Clearance
- Adjust dose for renal or hepatic Impairment
V. Dosing: Guanfacine (Tenex)
- Adults and children age >12 years
- Start 1 mg orally at bedtime
- Most effective dose is 1 mg
- May increase to 2-3 mg at bedtime after 3-4 weeks (as needed)
- Maximum: 3 mg/day
VI. Dosing: Guanabenz (Wytensin)
- Listed for historical purposes only (discontinued in U.S. outside of use in horses)
- Adult: 2 to 4 mg orally twice daily (up to 32 mg twice daily)
- Child (over age 12): 0.25 to 1 mg orally twice daily (up to 2 to 12 mg orally twice daily)
VII. Adverse Effects
- Dry Mouth
- Sedation
- Rebound Hypertension
- Less than with Clonidine
VIII. Drug Interactions
-
Thiazide Diuretics
- Increased Antihypertensive effect (Hypotension risk)
IX. Safety
- See Alpha Adrenergic Central Agonist
- Pregnancy Category B (Guanfacine)
- Unknown Safety in Lactation
X. Resources
XI. References
- Olson (2020) Clinical Pharmacology, MedMaster, Miami, p. 64-5
- Hamilton (2010) Tarascon Pocket Pharmacopeia, Jones and Bartlett, p. 76
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Related Studies
| guanfacine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
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