Comparison of nuclear scintigraphy and acetaminophen absorption as a meansof studying gastric emptying in horses

Objective-To evaluate the correlation between half-time of liquid-phase gas tric emptying (T-50), determined with nuclear scintigraphy using technetium Tc 99m pentetate, and absorption variables of orally administered acetamin ophen. Animals-6 mature horses. Procedure-Technetium Tc 99m pentetate (10 mCl) and acetaminophen (20 mg/kg of body weight) were administered simultaneously in 200 mi of water. Serial left and right lateral images of the stomach region were obtained with a g amma camera, and T-50 determined separately for counts obtained from the le ft side, the right side and the geometric mean. Power exponential curves we re used for estimation of T-50 and modified R-2 values for estimation of go odness of fit of the data. Serial serum samples were taken, and acetaminoph en concentration was determined, using fluorescence polarization immunoassa y. Maximum serum concentration (C-max), time to reach maximum serum concent ration (T-max), area under the curve for 240 minutes and the absorption con stant (K-a) were determined, using a parameter estimation program. Correlat ions were calculated, using the Spearman rank correlation coefficient. Results-Correlations between T-50 and T-max and between T-50 and K-a were s ignificant. Conclusions and Clinical Relevance-T-max and K-a are valuable variables in the assessment of liquid-phase gastric emptying using acetaminophen absorpt ion. Acetaminophen absorption may be a valuable alternative to nuclear scin tigraphy in the determination of gastric emptying rates in equine patients with normally functioning small intestine.