Guanfacine: profile and news

Myogen Reports 2005 Results  07 Mar 2006
Approximately 770 patients will be randomized to darusentan, active control (guanfacine, an antihypertensive drug that acts as a central alpha agonist) or ... - Business Wire (press release),

Monoaminergic Treatment of Schizophrenia  Feb 27, 2006
Guanfacine (Tenex), by enhancing signals at postsynaptic α 2 -adrenergic receptors, has been shown to improve working memory performance in animal models ... - Psychiatric Times,

The potential for increased sedation when guanfacine is given with other CNS-depressant drug should be appreciated. The administration of guanfacine concomitantly with 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.

TCAs decrease the hypotensive effect of guanfacine. Noncardioselective beta-blockers (nadolol,porpranolol,timolol) may exacerbate rebound hypertension when guanfacine is withdrawn. The beta-blocker should be withdrawn first. The gradual withdrawal of guafacine or a cardioselective beta-blocker could be substituted.

Anticoagulants

Ten patients who were stabilized on oral anticoagulants were given guanfacine, 1-2 mg/day, for 4 weeks. No changes were observed in the degree of anticoagulation. In several well-controlled studies, guanfacine was administered together with diuretics with no drug interactions reported. In the long-term safety studies, guanfacine was given concomitantly with many drugs without evidence of any interactions. The principal drugs given (number of patients in parentheses) were: cardiac glycosides (115), sedatives and hypnotics (103), coronary vasodilators (52), oral hypoglycemics (45), cough and cold preparations (45), NSAIDs (38), antihyperlipidemics (29), antigout drugs (24), oral contraceptives (18), bronchodilators (13), insulin (10), and beta blockers (10).

Laboratory Test

In clinical trials, no clinically relevant laboratory test abnormalities were identified as causally related to drug during short-term treatment with guanfacine.

Drug/Laboratory Test Interactions

No laboratory test abnormalities related to the use of guanfacine have been identified.