The comparative potency of intravenous nicardipine and verapamil on the cardiovascular response to tracheal intubation.

BACKGROUND

Two different types of calcium channel blockers (namely nicardipine and verapamil) have been used widely in clinical practice. However, no clinical studies have previously been performed to ascertain the relative potency of intravenous verapamil and nicardipine in the attenuation of cardiovascular response to tracheal intubation.

METHODS

We assessed the optimal dose and relative potency of verapamil and nicardipine in the attenuation of hemodynamic response to tracheal intubation in 135 healthy patients. Control group (Group D received normal saline i.v. Patients in Groups II-V received nicardipine 0.005, 0.01, 0.03 and 0.06 mg/kg i.v., respectively. Patients in Groups VI-IX received verapamil 0.03, 0.05, 0.1 and 0.15 mg/kg i.v., respectively. Anaesthesia was induced with propofol (2.5 mg/kg) and muscle relaxation was facilitated by vecuronium (0.2 mg/kg, i.v.). One min after induction, tracheal intubation was performed. Mean arterial pressure (MAP) was measured at 1 min interval from 10 min before induction to 15 min after induction.

RESULTS

The ED50 with 95% confidence interval of nicardipine and verapamil for the attenuation of 50% mean arterial pressure (MAP) increase after tracheal intubation were 14.55 micrograms/kg (8.25-25.67) and 75.4 micrograms/kg (58.7-96.95), respectively. The ED50 with 95% confidence interval of verapamil for the reduction of the 50% heart rate (HR) increase post tracheal intubation was 57.4 micrograms/kg (18-182.2). No differences were found in the frequency of perioperative arrhythmia, post-operative hypotension, postoperative emesis, dizziness, muscle weakness and muscle soreness within two hours following surgery, when compared control with experimental groups (p > 0.05).

CONCLUSIONS

These results suggest that verapamil and nicardipine attenuate the hypertensive response to tracheal intubation without significant adverse effects in healthy patients. The dose ratio (ED50 nicardipine and ED50 verapamil for MAP) with 95% confidence interval was revealed to be 2.3 (1.82-7.41).