GASTRIC FLUID VOLUME AND PH AFTER NIZATIDINE IN ADULTS UNDERGOING ELECTIVE SURGERY - INFLUENCE OF TIMING AND DOSE

We conducted a prospective, randomized, double-blind study to investigate the effect of oral nizatidine (150-600 mg) a new potent H-2 antagonist, on preoperative gastric fluid pH and volume in adults undergoing elective surgery. One hundred and seventy-five healthy adults (21-68 yr) were randomly allocated to seven treatment groups (n = 25); Placebo was administered at 21:00 and 06:30 the night before and on the day ofsurgery, respectively (0/0: control); nizatidine 150 mg at 21:00) and placebo at 06:30 (150/0); placebo at 21:00 and nizatidine 150 mg at 06:30 (0/150); nizatidine 150 mg at 21:00 and 06:30 (150/150); nizatidine 300 mg at 21:00 and placebo at 06:30 (300/0); placebo at 21:00 and nizatidine 300 mg at 06:30 (0/300); and nizatidine 300 mg at 21:00 and 06:30 (300/300). Each patient fasted overnight and took the drug and/or placebo with 20 ml water. After induction of anaesthesia, the pH and volume of gastric fluid obtained through an orogastric tube were measured. The mean pH of 0/150, 150/150, 300/0, 0/300, and 300/ 300 groups war; higher than that of the control group (P < 0.05). Gastric volume in these groups was smaller than in the control (P < 0.05). The 150/0 group failed to decrease gastric fluid volume and increase pH, In the 300/0 group, the gastric pH was lower than other regimens which effectively decreased gastric acidity (P < 0.05). The number of patients with a pN < 2.5 and a volume >0.4 ml . kg(-1) in the 0/150, 150/150, 0/300, and 300/300 groups (0%) was less than in the control group (16%)(P < 0.05). These data suggest that oral nizatidine in a dose of greater than or equal to 150 mg given on the morning ofsurgery decreases preoperative gastric acidity.