Class
- Antiadrenergic, alpha-2 agonist
Guanfacine
Commonly Prescribed for
(FDA approved in bold)
- Hypertension
- Gilles de la Tourette syndrome (GTS)
- Tics
- Attention deficit hyperactivity disorder (ADHD)
- Neuropathic pain
- Opioid detoxification
- Alcohol withdrawal
- Hypertensive “urgency”
- Post-traumatic stress disorder
Guanfacine
How the Drug Works
- Alpha-2 adrenergic agonist. Reduces sympathetic output from CNS, which decreases cardiac output, peripheral vascular resistance, and blood pressure
- Specifically targets alpha-2 receptors in the brainstem vasomotor center, decreasing presynaptic calcium levels and the release of norepinephrine
- Its effect in GTS and ADHD may be due to actions at the level of the prefrontal cortex
Guanfacine
How Long Until It Works
- Hypertension, withdrawal – less than 2 hours
- GTS – weeks to months
Guanfacine
If It Works
- In neurologic disorders, such as tics, continue to assess effect of the medication to see if it is still needed
Guanfacine
If It Doesn’t Work
- GTS/tics – Neuroleptics are often effective, but their use should be reserved for patients with significant social isolation or embarrassment
Guanfacine
Best Augmenting Combos for Partial Response or Treatment-Resistance
- In hypertension, combine with treatments less likely to cause orthostasis (angiotensin-converting enzyme inhibitors, diuretics)
- Tics and GTS symptoms may change over time. Many patients improve with age. Behavioral and psychological therapy are useful, and education and reassurance are all that is needed in mild cases
- Identify and treat comorbid conditions such as ADHD or obsessive-compulsive disorder
Guanfacine
Tests
- Monitor blood pressure and pulse
Adverse Effects (AEs)
Guanfacine
How Drug Causes AEs
- Related to alpha-2 adrenergic agonist effect – hypotension and sedation
Guanfacine
Notable AEs
- Dry mouth, drowsiness, dizziness, constipation, weakness, headache, depression, paresthesia, dermatitis, impotence, and syncope
Guanfacine
Life-Threatening or Dangerous AEs
- Bradycardia and syncope. Rapid withdrawal can cause rebound hypertension with increased catecholamine levels
Guanfacine
Weight Gain
- Unusual
Guanfacine
Sedation
- Not unusual