Pregabalin Versus Dexmedetomidine for Delirium Prevention After Cardiac Surgery

patients will receive pregabalin capsules (75 mg) will be given 2 h prior to induction of anesthesia and every 12 hours

patients will receive dexmedetomidine after induction of GA a bolus dose of 0.4 μg/kg dexmedetomidine (over a period of 10 to 20 min) followed by an infusion of 0.2 to 0.7 μg/kg/h