Guanfacine

Guanfacine tablets, USP are indicated in the management of hypertension. Guanfacine tablets, USP may be given alone or in combination with other antihypertensive agents, especially thiazide-type diuretics.

• 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 weeks 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 days to 4 days, which is delayed compared with clonidine hydrochloride
• This is consistent with the longer half-life of guanfacine
• In most cases, after abrupt withdrawal of guanfacine, blood pressure returns to pretreatment levels slowly (within 2 days to 4 days) without ill effects

Guanfacine tablets are contraindicated in patients with known hypersensitivity to guanfacine hydrochloride.

PRECAUTIONS General Like other antihypertensive agents, guanfacine hydrochloride should be used with caution in patients with severe coronary insufficiency, recent myocardial infarction, cerebrovascular disease, or chronic renal or hepatic failure. Sedation Guanfacine tablets, like other orally active central α 2 -adrenergic agonists, causes sedation or drowsiness, especially when beginning therapy. These symptoms are dose-related (see ADVERSE REACTIONS ). When guanfacine tablets are used with other centrally active depressants (such as phenothiazines, barbiturates, or benzodiazepines), the potential for additive sedative effects should be considered. …

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 tablets could not be established, should a rash occur, guanfacine tablets should be discontinued and the patient monitored appropriately. …

No reported abuse or dependence has been associated with the administration of guanfacine hydrochloride. OVERDOSAGE Signs and Symptoms Drowsiness, lethargy, bradycardia and hypotension have been observed following overdose with guanfacine. A 25-year-old female intentionally ingested 60 mg. She presented with severe drowsiness and bradycardia of 45 beats/minute. Gastric lavage was performed and an infusion of isoproterenol (0.8 mg in 12 hours) was administered. …

تناولها عندما تتذكر، إلا إذا اقترب موعد الجرعة التالية. عندها تخطَّ الجرعة المنسية. لا تتناول جرعتين معًا أبدًا للتعويض. راجع النشرة، فبعض الأدوية مختلفة.