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Guanfacine Dosage

Medically reviewed on March 15, 2018.

Applies to the following strengths: 1 mg; 2 mg; 3 mg; 4 mg

Usual Adult Dose for Hypertension

Initial dose: 1 mg orally once a day at bedtime; may increase to 2 mg once a day if satisfactory result not achieved after 3 to 4 weeks.

Comments: Adverse reactions increase significantly with doses above 3 mg/day.

Usual Pediatric Dose for Attention Deficit Disorder

6 YEARS TO LESS THAN 18 YEARS:
Initial dose: 1 mg orally once a day, either in the morning or evening, at approximately the same time each day; may adjust in increments of no more than 1 mg/week.

Recommended target dose: 0.05 to 0.12 mg/kg/day (total daily dose between 1 and 7 mg) once a day, depending on clinical response and tolerability

Maximum dose: 6 to 12 years: Doses above 4 mg/day have not been evaluated; 13 to 17 years: Doses above 7 mg/day have not been evaluated.

Comments: Attention Deficit Hyperactivity Disorder (ADHD) may require treatment for an extended period of time; healthcare providers should periodically reevaluate treatment and adjust dose as needed.

Use: Treatment of ADHD as monotherapy and as adjunctive therapy to stimulant medications.

Usual Pediatric Dose for Hypertension

12 YEARS OR OLDER:
Initial dose: 1 mg orally once a day at bedtime; may increase to 2 mg once a day if satisfactory result not achieved after 3 to 4 weeks.

Comments: Adverse reactions increase significantly with doses above 3 mg/day.

Renal Dose Adjustments

Dose adjustment(s) may be required; however, no specific guidelines have been suggested. Caution recommended.

Liver Dose Adjustments

Dose adjustment(s) may be required; however, no specific guidelines have been suggested. Caution recommended.

Dose Adjustments

ATTENTION DEFICIT HYPERACTIVITY DISORDER (ADHD):
Recommended Target Dose Ranges Based on Weight (0.05 to 0.12 mg/kg/day):
-25 to 33.9 kg: 2 to 3 mg/day
-34 to 41.4 kg: 2 to 4 mg/day
-41.5 to 49.4 kg: 3 to 5 mg/day
-49.5 to 58.4 kg: 3 to 6 mg/day
-58.5 to 91 kg: 4 to 7 mg/day
-Greater than 91 kg: 5 to 7 mg/day

Switching from Immediate Release to Extended Release: Discontinue immediate release and titrate extended release following the recommended dosing schedule. Do not substitute on a milligram per milligram basis.

Dosage Adjustment with Concomitant Use of Strong CYP450 3A4 Inhibitors:
-If initiating guanfacine while taking a strong CYP450 3A4 inhibitor: Decrease guanfacine dose by 50%
-If continuing guanfacine while adding a strong CYP450 3A4 inhibitor: Decrease guanfacine dose by 50%
-If continuing guanfacine and discontinuing the strong CYP450 3A4 inhibitor: Increase guanfacine to the recommended dose

Dosage Adjustment with Concomitant Use of Strong CYP450 3A4 Inducers:
-If initiating guanfacine while taking a strong CYP450 3A4 inducer: Consider increasing guanfacine to double the recommended dose
-If continuing guanfacine while adding a strong CYP450 3A4 inducer: Consider increasing guanfacine to double the recommended dose over 1 to 2 weeks
-If continuing guanfacine while discontinuing the strong CYP450 3A4 inducer: Decrease guanfacine to the recommended dose over 1 to 2 weeks

Precautions

Safety and efficacy have not been established in hypertensive patients younger than 12 years; safety and efficacy have not been established in Attention Deficit Hyperactivity Disorder (ADHD) patients younger than 6 years.

Consult WARNINGS section for additional precautions.

Dialysis

No adjustment recommended

Other Comments

Administration advice:
Extended release:
-Tablets should be swallowed whole. Do not crush, chew, or break.
-Do not administer with high fat meals.
-If a dose is missed, the next dose should be administered at the regular time. Consider titration based on patient tolerability when reinitiating patients to the previous maintenance dose after two or more missed consecutive doses.

Monitoring:
-General: Vital signs

Patient advice:
-Advise patients to exercise caution when operating dangerous machinery or driving motor vehicles until their response to this drug has been determined.
-Warn patients that their tolerance for alcohol and other CNS depressants may be diminished.
-Advise patients not to discontinue therapy abruptly.
-Advise patients with a history of syncope or those with a condition that predisposes them to syncope (e.g., hypotension, orthostatic hypotension, bradycardia, or dehydration) to avoid becoming dehydrated or overheated.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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