Effect of ranitidine on intragastric pH in clinically normal neonatal foals

Abstract

Objective: To determine intragastric pH in newborn foals and to examine the effect of i.v. or oral administration of an H2-receptor antagonist on intragastric pH.

Design: Prospective controlled study.

Animals: 6 healthy mixed-breed neonatal foals.

Procedure: Intragastric pH was measured, using an antimony electrode. Foals were monitored on days 2, 4, and 6 after birth, and each received 3 treatments. The pH was recorded for 4 hours before treatment and for 10 hours after ranitidine administration (2 mg/kg [0.91 mg/lb] of body weight, i.v.; 6.6 mg/kg [3 mg/lb], PO) or 20 hours after corn syrup administration. Mean and median pH and percentage of time pH was > or = 4 were calculated.

Results: Mean intragastric pH significantly increased for 5 hours after i.v. administration of ranitidine, compared with baseline data. Percentage of time intragastric pH was > or = 4 increased significantly for 4 hours after ranitidine administration, and median pH increased significantly for hours 2 to 4 after administration. Oral administration of ranitidine significantly increased mean and median pH for hours 2 to 8 after administration and percentage of time pH was > or = 4 for hours 2 to 7 after administration.

Clinical implications: Neonatal foals have highly acidic gastric fluid. Intravenous or oral administration of ranitidine significantly increased intragastric pH for 4 and 8 hours, respectively. Suckling affected intragastric pH and underscored the need for frequent feeding of neonatal foals.