Guanfacineinteractions

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). 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 hydrochloride was given concomitantly with many drugs without evidence of any interactions. The principal drugs given (number of patients in parentheses) were: cardiac glycosides, sedatives and hypnotics, coronary vasodilators, oral hypoglycemics, cough and cold preparations, NSAIDs, antihyperlipidemics, antigout drugs, oral contraceptives, bronchodilators, insulin, and beta blockers. Drug/Laboratory Test Interactions No laboratory test abnormalities related to the use of guanfacine hydrochloride have been identified.