General anesthesia in children is tied to a risk of pulmonary aspiration of gastric contents.

A study was conducted to assess whether preoperative oral pirenzepine reduces gastric fluid at anesthesia induction in children. Another aim of the study was to determine if a combination of pirenzepine and ranitidine is more effective than each drug given alone in pediatric anesthesia.

A two-part controlled study was designed to determine the efficacy of preoperative oral pirenzepine, ranitidine, and the combination of pirenzepine and ranitidine in controlling gastric fluid pH and volume in 210 ASA I children, aged between 2 and 14 years, who were scheduled for elective surgery.

• In the first part of the study with 90 children, lower dose pirenzepine did not have a significant effect on fluid volume. It did not reduce gastric fluid acidity significantly, irrespective of dose. However, the proportion of children who were considered to have a risk for aspiration pneumonitis was decreased with pirenzepine 25 mg (P <0.05), but not with 12.5 mg.
• In the second part, the other 120 children were randomized to one of the four treatment groups: pirenzepine 25 mg with placebo; ranitidine 75 mg with placebo; pirenzepine 25 mg with ranitidine 75 mg; and placebo and placebo. These treatment was administered 1 h prior to anesthesia.
• Pirenzepine 25 mg led to a reduction in gastric fluid volume (P <0.05) but did not increase gastric pH.
• Ranitidine 75 mg increased gastric pH (P <0.05).
• The combination of pirenzepine and ranitidine led to a reduction in gastric fluid acidity as well as volume (P <0.05).
• Combined use of the two drugs decreased the number of children considered to be at risk to zero.

To conclude, the combination of pirenzepine and ranitidine is effective at improving the gastric fluid environment.

Source: Maekawa N, Nishina K, Mikawa K, et al. Comparison of pirenzepine, ranitidine, and pirenzepine-ranitidine combination for reducing preoperative gastric fluid acidity and volume in children. Br J Anaesth. 1998 Jan;80(1):53-7.