ACETAMINOPHEN AS A MARKER OF GASTRIC-EMPTYING IN PONIES

Gastric emptying was evaluated in ponies using the acetaminophen (AP) method. Fifteen minutes after i.v. administration of metoclopramide, e rythromycin, yohimbine, atropine or saline, the ponies were given AP b y stomach tube. Blood samples for AP analysis were collected at baseli ne and 15, 30, 45, 60, 75, 90, 105 and 120 min after AP administration . Time to reach peak serum concentration (T-max), maximum serum concen tration (C-max) and area under the AP serum concentration vs. time cur ve (AUC) were determined for each treatment group. In the control grou p, T-max was 31 min and this decreased significantly (P<0.05) followin g the administration of metoclopramide. Atropine significantly increas ed T-max and decreased C-max and AUC. Yohimbine significantly increase d AUC. Erythromycin did not significantly change any parameter. This s tudy indicates that acetaminophen can be used to evaluate gastric empt ying in ponies, The method is easy to perform and is minimally invasiv e. Metoclopramide stimulated gastric emptying of liquid in healthy, fa sting ponies, Atropine significantly delayed, while erythromycin had l ittle effect on, gastric emptying. Yohimbine increased the cumulative absorption of AP.