Drug Interactions between guanfacine and Rapiblyk

Consumer information for this interaction is not currently available.

MONITOR: Use of central alpha-2 adrenergic agonists, such as clonidine or guanfacine, with beta-blockers may have synergistic pharmacodynamic effects resulting in AV block, bradycardia, and hypotension. In addition, sinus node dysfunction may also be enhanced. Abrupt withdrawal of an alpha-2 agonist or both the alpha-2 agonist and the beta-blocker may also result in rebound hypertensive effects. Increased blood pressure, hypertensive crisis, hypertensive encephalopathy, strokes, and fatalities have been reported after clonidine withdrawal. The proposed mechanism is related to increased catecholamine release after alpha-2 agonist withdrawal which, when combined with concurrent beta-blockade, results in unopposed vasoconstriction. Data are available for clonidine; however, the manufacturer of guanfacine states that beta-blockers and guanfacine have been given concomitantly without evidence of any interactions in long-term safety studies. Patients who discontinued clonidine while taking noncardioselective beta blockers appeared to be at a higher risk of developing rebound hypertension.

MANAGEMENT: Until more information is available, caution and close monitoring of blood pressure are recommended for patients receiving guanfacine with a beta-blocker. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some patients. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, headaches, or reduced or irregular heart rate.