TENEX - guanfacine hydrochloride tablet
Promius Pharma, LLC
structurelabelTenex1mg
Tenex (guanfacine hydrochloride) is a centrally acting antihypertensive with ?2 -adrenoceptor agonist properties in tablet form for oral administration.
The chemical name of Tenex (guanfacine hydrochloride) is N-amidino- 2-(2,6-dichlorophenyl) acetamide hydrochloride and its molecular weight is 282.56
Guanfacine hydrochloride is a white to off-white powder; sparingly soluble in water and alcohol and slightly soluble in acetone. The tablets contain the following inactive ingredients:
1 mg-FD&C Red 40 aluminum lake, lactose, microcrystalline cellulose, povidone, stearic acid.
2 mg-D&C Yellow 10 aluminum lake, lactose, microcrystalline cellulose, povidone, stearic acid.
CLINICAL PHARMACOLOGY
Tenex (guanfacine hydrochloride) is an orally active antihypertensive agent whose principal mechanism of action appears to be stimulation of central ?2 -adrenergic receptors. By stimulating these receptors, guanfacine reduces sympathetic nerve impulses from the vasomotor center to the heart and blood vessels. This results in a decrease in peripheral vascular resistance and a reduction in heart rate.
INDICATIONS AND USAGE
Tenex (guanfacine hydrochloride) is indicated in the management of hypertension. Tenex may be given alone or in combination with other antihypertensive agents, especially thiazide-type diuretics.
CONTRAINDICATIONS
Tenex is contraindicated in patients with known hypersensitivity to guanfacine hydrochloride.
PRECAUTIONS
General
Like other antihypertensive agents, Tenex (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
Tenex, like other orally active central ?2 -adrenergic agonists, causes sedation or drowsiness, especially when beginning therapy. These symptoms are dose-related (see ADVERSE REACTIONS). When Tenex is used with other centrally active depressants (such as phenothiazines, barbiturates, or benzodiazepines), the potential for additive sedative effects should be considered.
Rebound
Abrupt cessation of therapy with orally active central ?2 -adrenergic agonists may be associated with increases (from depressed on-therapy levels) in plasma and urinary catecholamines, symptoms of "nervousness and anxiety" and, less commonly, increases in blood pressure to levels significantly greater than those prior to therapy.
DOSAGE AND ADMINISTRATION
The recommended initial dose of Tenex (guanfacine hydrochloride) 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 Tenex is 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 - 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 - 4 days) without ill effects.
