Guanfacine is a selective α2A-adrenergic receptor agonist primarily used to treat Attention Deficit Hyperactivity Disorder (ADHD) and hypertension. Its mechanism of action involves activating α2A receptors in specific brain neurons, regulating sympathetic nervous activity to stabilize blood pressure and improve attention deficit symptoms.
This medication has central antihypertensive effects, reducing blood pressure fluctuations with a weaker vasoconstrictive effect on peripheral blood vessels, thus presenting a lower risk of hypotension. In ADHD treatment, guanfacine can enhance focus and reduce impulsive behaviors, making it an important non-stimulant medication option.
The generic name is Guanfacine, with main brand names including:
Guanfacine is classified as an α-2 adrenergic receptor agonist, belonging to the category of sympatholytic agents. Its pharmacological action differs from traditional β-blockers, primarily acting on the central nervous system with a weaker effect on peripheral vascular smooth muscle, resulting in a more stable blood pressure-lowering effect.
In the context of ADHD, it is categorized as a non-stimulant (Non-stimulant), with a different mechanism of action from stimulant drugs like methylphenidate, suitable for patients intolerant to stimulants.
Main indications include:
In clinical practice, Intuniv is specifically designed for ADHD, with dosage adjustments based on age and weight. For hypertension, it is usually administered once daily with regular blood pressure monitoring.
Common mild side effects include:
Serious side effects may include:
Contraindications: Patients allergic to guanfacine or its components should not use. Those with severe bradycardia, sick sinus syndrome, or second-degree or higher atrioventricular block should avoid use.
Pregnancy and Lactation: Pregnancy category C indicates potential risk to the fetus; benefits and risks should be evaluated in pregnant or planning pregnancy. It may be secreted into breast milk, so caution is advised during breastfeeding.
Concurrent use with the following medications may enhance antihypertensive effects:
Avoid combining with peripheral α-adrenergic antagonists (e.g., doxazosin), which may cause severe hypotension. When taking SSRIs, blood pressure should be monitored for changes.
Hypertension:
ADHD:
If a dose is missed, it should be taken as soon as remembered, but if less than 6 hours remain before the next dose, skip the missed dose and resume normal schedule the next day. Do not double the dose to reduce the risk of hypotension.
Overdose may cause severe hypotension and bradycardia, requiring immediate medical attention. Symptoms include confusion, fainting, and difficulty breathing. Emergency treatment involves blood pressure support and symptom monitoring in a hospital setting.
Q: Is there a specific dietary timing recommended when taking Guanfacine?
It is recommended to take it at the same time daily, either before or after meals. If gastrointestinal discomfort occurs, taking it with food may help alleviate symptoms. Avoid high-fat meals simultaneously, as they may delay the onset of action.
Q: How should I respond if I experience side effects like dizziness or headache?
Initial mild dizziness or headache is common and usually diminishes as the body adjusts. Try to change positions slowly (e.g., sit for 1 minute before standing) and maintain regular sleep patterns. If symptoms persist beyond two weeks or worsen, consult a doctor for dose adjustment.
Q: What precautions should be taken when combining with other antihypertensive drugs?
Combining with other antihypertensives (e.g., β-blockers, diuretics) may enhance blood pressure reduction, requiring regular monitoring. The doctor will adjust doses based on blood pressure readings. Patients should not alter doses without medical advice to prevent hypotensive crises.
Q: Does long-term use of Guanfacine affect liver or kidney function?
Current clinical studies suggest that at prescribed doses, long-term effects on liver and kidney function are minimal. Patients with chronic kidney or liver disease should have regular function tests. If unexplained fatigue, jaundice, or edema occurs, discontinue medication and seek medical attention.
Q: Can Guanfacine be used during pregnancy or breastfeeding?
Use during pregnancy should be cautious; there is limited clinical data on safety. During breastfeeding, it should be avoided as the drug may pass into breast milk. If planning pregnancy or currently breastfeeding, inform your healthcare provider to evaluate alternative treatments.
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