Guanfacine
Hypertension, Attention Deficit Disorder with Hyperactivity
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Drug Status
Government Approvals
US(FDA), UK(BNF)
WHO Essential Medicine
NO
Known Teratogen
No
Pharmaceutical Class
Central alpha-2 Adrenergic Agonist
Controlled Drug Substance
No
Guanfacine
Summary
Guanfacine is primarily used to treat Attention Deficit Hyperactivity Disorder (ADHD) in children and adolescents. It helps reduce symptoms of hyperactivity and impulsivity.
Guanfacine works by stimulating alpha2A-adrenergic receptors in the brain. This action helps decrease hyperactivity and impulsivity in ADHD by modulating neurotransmitter activity in the brain.
Guanfacine is typically taken once daily, either in the morning or evening. The usual dose range for children is between 1 to 7 mg per day, depending on weight and response.
Common side effects of Guanfacine include drowsiness, fatigue, and headaches. Other side effects can include decreased appetite, irritability, sleep disturbances, and gastrointestinal issues like abdominal pain, nausea, and constipation.
Guanfacine should not be used by patients with a history of hypersensitivity to the drug. It's also important to avoid abrupt discontinuation to prevent rebound hypertension. Patients should be monitored for cardiovascular effects.
Indications and Purpose
How does Guanfacine work?
Guanfacine acts as a selective central alpha2A-adrenergic receptor agonist, which reduces sympathetic nerve impulses from the vasomotor center to the heart and blood vessels. This action decreases peripheral vascular resistance and heart rate, helping to manage symptoms of ADHD.
Is Guanfacine effective?
Guanfacine's efficacy in treating ADHD has been established through several clinical trials. These include five short-term, placebo-controlled monotherapy trials and one long-term, placebo-controlled monotherapy maintenance trial. The trials demonstrated significant improvements in ADHD symptoms compared to placebo.
What is Guanfacine?
Guanfacine is primarily used to treat Attention Deficit Hyperactivity Disorder (ADHD) in children and adolescents. It works by stimulating central alpha2A-adrenergic receptors, reducing sympathetic nerve impulses, which helps decrease hyperactivity and improve attention. Unlike stimulants, Guanfacine is not a central nervous system stimulant.
Directions for Use
For how long do I take Guanfacine?
Guanfacine may be needed for extended periods, especially for managing ADHD. Healthcare providers should periodically re-evaluate the long-term use of Guanfacine and adjust the dosage as needed based on the patient's response and tolerability.
How do I take Guanfacine?
Guanfacine should be taken once daily, either in the morning or evening, and swallowed whole with water, milk, or other liquid. It should not be taken with high-fat meals, as this can increase drug exposure. Patients should avoid alcohol and consult their healthcare provider for any specific dietary restrictions.
How long does it take for Guanfacine to start working?
Guanfacine typically begins to show effects within one to two weeks of starting treatment. However, it may take several weeks to achieve the full therapeutic effect, and dosage adjustments may be necessary based on the patient's response and tolerability.
How should I store Guanfacine?
Guanfacine should be stored at room temperature, between 20°C to 25°C (68°F to 77°F), with excursions permitted from 15°C to 30°C (59°F to 86°F). It should be protected from moisture and kept out of reach of children.
What is the usual dose of Guanfacine?
The usual daily dose of Guanfacine for children and adolescents aged 6 to 17 years is based on weight, ranging from 1 mg to 7 mg per day. For children weighing 25-33.9 kg, the dose is 2-3 mg/day, and for those over 91 kg, it is 5-7 mg/day. Guanfacine is not typically prescribed for adults for ADHD, so dosing information for adults is not provided.
Warnings and Precautions
Can Guanfacine be taken safely while breastfeeding?
There is no data on the presence of Guanfacine in human milk or its effects on the breastfed infant. Breastfeeding mothers should monitor infants for symptoms like sedation and poor feeding. The benefits of breastfeeding should be weighed against the mother's need for Guanfacine and any potential adverse effects on the infant.
Can Guanfacine be taken safely while pregnant?
There is limited data on the use of Guanfacine during pregnancy, and no strong evidence of fetal harm from human studies. However, it is recommended to use Guanfacine during pregnancy only if the potential benefit justifies the potential risk to the fetus. Pregnant women should consult their healthcare provider.
Can I take Guanfacine with other prescription drugs?
Significant drug interactions with Guanfacine include CYP3A4 inhibitors (e.g., ketoconazole) and inducers (e.g., carbamazepine), which can alter Guanfacine's plasma concentration. Patients should also be cautious when using antihypertensives, sedatives, and alcohol, as these can enhance Guanfacine's effects.
Is Guanfacine safe for the elderly?
The safety and efficacy of Guanfacine in geriatric patients have not been established. Therefore, it is not typically recommended for use in the elderly. If prescribed, careful monitoring for side effects such as hypotension and bradycardia is advised.
Is it safe to drink alcohol while taking Guanfacine?
Drinking alcohol while taking Guanfacine can increase the sedative effects of the medication, leading to increased drowsiness and dizziness. It is advised to avoid alcohol consumption while on Guanfacine to prevent these enhanced effects.
Is it safe to exercise while taking Guanfacine?
Guanfacine can cause side effects like dizziness, fatigue, and hypotension, which may affect your ability to exercise safely. If you experience these symptoms, it is advisable to avoid strenuous activities and consult your healthcare provider for guidance on safe exercise practices while taking Guanfacine.
Who should avoid taking Guanfacine?
Important warnings for Guanfacine include the risk of hypotension, bradycardia, and sedation. It is contraindicated in patients with a history of hypersensitivity to Guanfacine or its ingredients. Patients should avoid abrupt discontinuation to prevent rebound hypertension and should be cautious when using alcohol or other sedatives.
