Guanfacine Dosage

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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, when given alone or in combination with another antihypertensive drug.
Maintenance dose: 1 to 3 mg orally once a day at bedtime.

Usual Pediatric Dose for Attention Deficit Disorder

Only the guanfacine extended-release formulation is indicated for ADHD.

Children 6 to 17 years of age:

Initial dose: 1 mg extended-release orally once a day in the morning

Dosage should be adjusted in increments of no more than 1 mg/week.

Maintenance dose: 1 to 4 mg extended-release orally once daily in the morning, depending on clinical response and tolerability.

Renal Dose Adjustments

When prescribing for patients with renal impairment, the low end of the dosing range should be used.

Liver Dose Adjustments

Data not available

Dose Adjustments

If after 3 to 4 weeks of guanfacine immediate-release therapy the 1 mg does not give a satisfactory result, a dose of 2 mg may be given. Most of the effect of guanfacine is seen at 1 mg. Higher daily doses have been used, but adverse reactions increase significantly with doses above 3 mg/day.

Precautions

Guanfacine extended-release should not be substituted for guanfacine immediate-release on a mg to mg basis, because of differing pharmacokinetic profiles.

Guanfacine extended-release should be dosed once daily, and should not be crushed, chewed or broken before swallowing because this will increase the rate of guanfacine release. It should not be administered with high fat meals, due to increased exposure.

The effectiveness of guanfacine extended-release for longer-term use (more than 9 weeks) has not evaluated in controlled trials. Health care providers electing to use guanfacine extended-release for extended periods should periodically reevaluate the long-term usefulness of the drug for the individual patient.

If patients are switched from the immediate-release to the extended-release formulation, the immediate-release should be discontinued and the extended- release titrated according to manufacturer guidelines.

Guanfacine extended-release has not been studied for doses over 4 mg per day.

Safety and effectiveness have not been established in pediatric patients less than 6 years of age.

Dialysis

Patients on dialysis can be given usual doses of guanfacine hydrochloride as the drug is poorly dialyzed.

Other Comments

Infrequent, transient elevations in blood pressure above original baseline (i.e., rebound) have been reported to occur upon abrupt discontinuation of guanfacine. To minimize these effects, the dose should generally be tapered in decrements of no more than 1 mg every 3 to 7 days.

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