For each patient, bolus dose of the each study drug will be administered slowly over 10 min, after mouth gag insertion and patient positioning (either lateral or prone position) followed by induction with propofol in a dose of 0.5-1.5 mgkg-1, targeting BIS between 60-70.Once the target BIS is attained, the infusion of the study drug is started with the pre-adjusted rate (discussed before) along with the propofol maintenance infusion starting at a rate of 3 mg/kg/hr to be adjusted to maintain a BIS value between 60-70.At the end of the procedure, propofol and study drug infusions will be stopped. BIS values will be allowed equilibrating above 80. Patients oropharynx will be thoroughly suctioned and patients will be turned supine with head up tilt (15 degrees), to allow for complete recovery with eye opening on command, ability to handle secretions, follow simple commands, hemodynamic stability, maintaining O2 saturation at room air >95% and attainment of BIS value >90 as end points