Guanfacine (Tenex)
Purpose of Medication and Method of Action
Guanfacine is indicated in the management of high blood pressure. It acts by reducing the adrenergic nerve stimuli from the brain which produce vasoconstriction and contribute to high blood pressure. The result is a reduction in blood pressure and a reduced heart rate.
Side Effects
The most common side effects are: dry mouth (10% with 1 mg dose and 50% with a 3 mg dose), drowsiness (20%), dizziness (10%), constipation (8%), weakness (8%) and headache (4%).
Drug Interactions
Increased sedation may occur when Guanfacine is given with other drugs which can depress central nervous system function. Phenytoin or phenobarbital added to therapy may reduce the blood levels of Guanfacine and require an upward adjustment of dose to maintain control of blood pressure.
Cautions and Contraindications
None
Usual Dose
1 mg each day at bedtime increasing to 2 mg daily if required.
Note
IMPORTANT! If discontinued - it is important that the dose be slowly tapered downward to avoid rebound hypertension.
Patient Medication Information
These information sheets do not list all known side effects of the medications, only the most common side effects. For a complete list of side effects please contact your local pharmacy or the actual drug manufacturing company.