Skip to Content

Guanfacine Dosage

Applies to the following strength(s): 1 mg ; 2 mg ; 3 mg ; 4 mg

The information at Drugs.com is not a substitute for medical advice. Always consult your doctor or pharmacist.

Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

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.
-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.

Hide