Guanfacine Hydrochloride
Generic Name: guanfacine hydrochloride
Brand Names:
Guanfacine Hydrochloride
DESCRIPTION Guanfacine tablets, USP are a centrally acting antihypertensive with α 2 -adrenoceptor agonist properties in tablet form for oral administration. The chemical name of guanfacine hydrochloride is N-amidino-2-(2,6-dichlorophenyl) acetamide monohydrochloride and its molecular weight is 282.55. Its structural formula is: Guanfacine hydrochloride, USP is a white or almost white crystalline powder; sparingly soluble in water, methanol and ethanol.
Overview
DESCRIPTION Guanfacine tablets, USP are a centrally acting antihypertensive with α 2 -adrenoceptor agonist properties in tablet form for oral administration. The chemical name of guanfacine hydrochloride is N-amidino-2-(2,6-dichlorophenyl) acetamide monohydrochloride and its molecular weight is 282.55. Its structural formula is: Guanfacine hydrochloride, USP is a white or almost white crystalline powder; sparingly soluble in water, methanol and ethanol.
Uses
INDICATIONS AND USAGE Guanfacine tablets are indicated in the management of hypertension. Guanfacine tablets may be given alone or in combination with other antihypertensive agents, especially thiazide-type diuretics.
Dosage
DOSAGE AND ADMINISTRATION The recommended initial dose of guanfacine tablets when given alone or in combination with another antihypertensive drug is 1 mg daily given at bedtime to minimize somnolence. If after 3 to 4 weeks of therapy 1 mg does not give a satisfactory result, a dose of 2 mg may be given, although most of the effect of guanfacine tablets are seen at 1 mg (see CLINICAL PHARMACOLOGY ). Higher daily doses have been used, but adverse reactions increase significantly with doses above 3 mg/day. The frequency of rebound hypertension is low, but it can occur. When rebound occurs, it does so after 2 to 4 days, which is delayed compared with clonidine hydrochloride. This is consistent with the longer half-life of guanfacine.
Side Effects
ADVERSE REACTIONS Adverse reactions noted with guanfacine hydrochloride are similar to those of other drugs of the central α 2 -adrenoreceptor agonist class: dry mouth, sedation (somnolence), weakness (asthenia), dizziness, constipation, and impotence. While the reactions are common, most are mild and tend to disappear on continued dosing. Skin rash with exfoliation has been reported in a few cases; although clear cause and effect relationships to guanfacine hydrochloride could not be established, should a rash occur, guanfacine hydrochloride should be discontinued and the patient monitored appropriately.
Interactions
Drug Interactions The potential for increased sedation when guanfacine hydrochloride is given with other CNS-depressant drugs should be appreciated. The administration of guanfacine concomitantly with a known microsomal enzyme inducer (phenobarbital or phenytoin) to two patients with renal impairment reportedly resulted in significant reductions in elimination half-life and plasma concentration. In such cases, therefore, more frequent dosing may be required to achieve or maintain the desired hypotensive response. Further, if guanfacine is to be discontinued in such patients, careful tapering of the dosage may be necessary in order to avoid rebound phenomena (see Rebound above).
Warnings
CONTRAINDICATIONS Guanfacine tablets are contraindicated in patients with known hypersensitivity to guanfacine hydrochloride.
Pregnancy
Pregnancy Administration of guanfacine to rats at 70 times the maximum recommended human dose and to rabbits at 20 times the maximum recommended human dose resulted in no evidence of harm to the fetus. Higher doses (100 and 200 times the maximum recommended human dose in rabbits and rats respectively) were associated with reduced fetal survival and maternal toxicity. Rat experiments have shown that guanfacine crosses the placenta. There are, however, no adequate and well-controlled studies in pregnant women.
Storage
HOW SUPPLIED Guanfacine tablets, USP are available in the following dosing strengths (expressed in equivalent amounts of guanfacine): 2 mg – Light blue, mottled, round, flat-faced, beveled-edge, uncoated tablets debossed with "U" on one side and "46" on the other side. NDC: 70518-3516-00 PACKAGING: 30 in 1 BLISTER PACK Store at controlled temperature, between 20° and 25°C (68°F and 77°F).
Frequently Asked Questions
What is Guanfacine Hydrochloride used for?▼
INDICATIONS AND USAGE Guanfacine tablets are indicated in the management of hypertension. Guanfacine tablets may be given alone or in combination with other antihypertensive agents, especially thiazide-type diuretics.
What are the side effects of Guanfacine Hydrochloride?▼
ADVERSE REACTIONS Adverse reactions noted with guanfacine hydrochloride are similar to those of other drugs of the central α 2 -adrenoreceptor agonist class: dry mouth, sedation (somnolence), weakness (asthenia), dizziness, constipation, and impotence. While the reactions are common, most are mild and tend to disappear on continued dosing. Skin rash with exfoliation has been reported in a few cases; although clear cause and effect relationships to guanfacine hydrochloride could not be established, should a rash occur, guanfacine hydrochloride should be discontinued and the patient monitored appropriately.
Can I take Guanfacine Hydrochloride during pregnancy?▼
Pregnancy Administration of guanfacine to rats at 70 times the maximum recommended human dose and to rabbits at 20 times the maximum recommended human dose resulted in no evidence of harm to the fetus. Higher doses (100 and 200 times the maximum recommended human dose in rabbits and rats respectively) were associated with reduced fetal survival and maternal toxicity. Rat experiments have shown that guanfacine crosses the placenta. There are, however, no adequate and well-controlled studies in pregnant women.
What are the important warnings for Guanfacine Hydrochloride?▼
CONTRAINDICATIONS Guanfacine tablets are contraindicated in patients with known hypersensitivity to guanfacine hydrochloride.
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Medical Disclaimer
This drug information is for educational purposes only and should not replace professional medical advice. Drug information is sourced from the FDA National Drug Code Directory and Structured Product Labeling. Always consult with a healthcare provider before starting, stopping, or changing any medication.