What information does the detailed package insert for Guanfacine contain?

1. Drug name and basic information

Guanfacine is a selectiveα-2A adrenoceptor agonist, mainly used in the neuropsychiatric field. Trade names include Intuniv (international common name) and インチュニプ (Japanese trade name), which is sometimes translated as guanfacine in clinical practice. As a non-stimulant drug, guanfacine is of great value in the treatment of ADHD in children and adolescents. It can be used as a monotherapy or in combination with central stimulants to enhance the efficacy or improve the tolerance of stimulating drugs.

2. Indications

The main clinical indication for guanfacine is attention deficit hyperactivity disorder (ADHD). Its clinical advantage is that it can reduce symptoms of hyperactivity, impulsivity, and distractibility in children and adolescents while improving daily functioning and academic performance with less risk. In clinical practice, guanfacine can also be used as an auxiliary therapy with other stimulant drugs for complex cases that require combined treatment, especially when stimulants alone have side effects or the efficacy is not satisfactory.

3. Usage and dosage

Guanfacine is an oral sustained-release tablet that should be swallowed whole and should not be crushed, chewed or cut to avoid abnormal drug release rates. Taking it with high-fat food may increase drug exposure, so it is recommended to take it on a relatively empty stomach or with a normal diet. Take it orally once a day, and the dosage time in the morning and evening should be as fixed as possible to ensure the stability of blood concentration. The starting dose is usually 1 mg/day, with weekly increments of no more than 1 mg. Based on clinical trial data and patient weight, the target dose is generally 0.05–0.12 mg/kg/day, and the total daily dose can range from 1–7 mg. Specific dosages for different weight ranges for children and adolescents are as follows:

25–33.9kg: 2–3mg/day

34–41.4kg: 2–4mg/day

41.5–49.4kg: 3–5mg/day

49.5–58.4kg: 3–6mg/day

58.5–91kg: 4–7mg/day

＞91kg: 5–7mg/day

Guanfacine usually requires long-term maintenance treatment, and medical providers should regularly evaluate efficacy and tolerability and adjust dosage to ensure safety and sustained efficacy. If the drug needs to be discontinued, the dose should be gradually reduced to no more than 1mg every 3 to 7 days to prevent blood pressure from rising and heart rate from rebounding. For missed doses, the dose should be adjusted appropriately according to the patient's tolerance and avoid taking it all at once.

4. Adverse reactions

Common side effects of guanfacine include drowsiness, headache, fatigue, upper abdominal discomfort, and mild sedation. More serious side effects, although uncommon but still a cause for concern, include low blood pressure, slowed heart rate, syncope, and weight gain.

5. Supply and storage

Guanfacine is available1mg, 2mg, 3mg and 4mg extended-release tablets, each bottle containing 100 tablets. Medications should be stored at 20°C to 25°C (68°F to 77°F), with an allowed deviation of 15°C to 30°C (59°F to 86°F), away from moisture, high temperatures and direct sunlight to maintain the stability and efficacy of the medication.

6. Contraindications and Precautions

It should be contraindicated in patients allergic to guanfacine or the inactive ingredients of the drug. There have been clinical reports of allergic reactions such as rash and itching, so please pay attention during use. Children with cardiovascular disease, abnormal blood pressure, or children with a history of severe sedation should be used with caution under the guidance of a professional physician.

7. Mechanism of action

Guanfacine modulates the effects of sympathetic nerves on the cardiovascular system by selectively activatingα-2A adrenergic receptors, thereby affecting the neural regulation of the prefrontal lobe in the brain. Although its exact molecular mechanism has not yet been fully elucidated, clinical data show that the drug can improve attention, impulse control and daily functions in patients with ADHD, providing a new non-stimulant treatment option for ADHD patients.

Reference materials:https://go.drugbank.com/drugs/DB01018