From the Guidelines
For a 14-year-old patient, guanfacine is typically started at 1 mg once daily, with a recommended target dose range of 0.05 to 0.12 mg/kg/d or 1 to 7 mg/d. The dose can be gradually increased by 1 mg per week based on clinical response and tolerability, as tolerated, to the recommended target dose range 1. It is essential to monitor blood pressure and heart rate, especially during dose adjustments, as guanfacine was originally developed as an antihypertensive medication. Extended-release formulations (Intuniv) are preferred for ADHD treatment due to once-daily dosing and more stable blood levels. Common side effects include drowsiness, fatigue, dry mouth, and occasionally hypotension. The medication works by stimulating alpha-2A adrenergic receptors in the prefrontal cortex, which helps improve attention and impulse control.
Some key points to consider when prescribing guanfacine include:
- The medication should be taken at the same time each day
- It is crucial not to abruptly discontinue guanfacine as this can cause rebound hypertension
- Weight-based dosing is not typically used for guanfacine in adolescents, but monitoring blood pressure and heart rate is vital, especially during dose adjustments 1.
It is also important to note that guanfacine has a different mechanism of action compared to other ADHD medications, and its use should be carefully considered based on the individual patient's needs and medical history 1.
From the Research
Dosage of Guanfacine for Pediatric Patients
The dosage of guanfacine for a pediatric patient 14 years old is not explicitly stated in the provided studies. However, some studies provide information on the dosage of guanfacine for adolescents with attention-deficit/hyperactivity disorder (ADHD).
- The study 2 suggests that weight-adjusted doses of guanfacine extended release >0.08 mg/kg but ≤0.12 mg/kg, if tolerated, may provide additional clinical benefits for adolescents with ADHD.
- The study 3 evaluated the pharmacokinetics of an oral extended-release formulation of guanfacine in children and adolescents with ADHD, and found that the mean plasma concentrations and concentration-related pharmacokinetic parameters were higher in children than in adolescents.
- The study 4 tested the hypothesis that combined effects of a dopamine and noradrenergic agonist, d-methylphenidate extended-release with guanfacine, would be clinically superior to either monotherapy and would have equal tolerability, and found that the combination treatment showed consistent evidence of clinical benefits over monotherapies.
Possible Dosage Range
Based on the study 2, the possible dosage range for a 14-year-old pediatric patient with ADHD could be:
- 0.08 mg/kg to 0.12 mg/kg per day, which would be approximately 4-6 mg per day for a patient weighing 50-60 kg.
- However, the study 3 found that the mean plasma concentrations and concentration-related pharmacokinetic parameters were higher in children than in adolescents, which may suggest that a lower dosage may be sufficient for a 14-year-old patient.
Important Considerations
- The study 5 highlights the importance of recognizing specific medication formulations and the need for careful medication prescribing and dispensing, as formulation errors can cause profound adverse effects.
- The study 4 found that sedation, somnolence, lethargy, and fatigue were greater in both guanfacine groups, which suggests that patients should be monitored for these adverse effects.