Objective—To apply an in vitro model for assessment of the solid-phase binding capacity of acetaminophen and thus assess the reliability of this marker for evaluation of solid-phase gastric emptying in vivo in animals.
Sample Population—4 test meals.
Procedures—A spectrophotometric method for detection of acetaminophen was validated and applied for assessment of the percentage retention of acetaminophen in the solid phase of 4 test meals. The gastric milieu was simulated by incubating each meal in artificial gastric juice for 2 hours in a shaking water bath maintained at 37°C. Solid-phase retention was then assessed 3 times by measuring the amount of acetaminophen that had leached into the liquid phase.
Results—Acetaminophen was poorly retained in the solid phase of all the test meals examined in the study. There was also a large degree of variability in the percentage retention for each meal when the experiment was repeated 3 times.
Conclusions and Clinical Relevance—Analysis of the results of this in vitro study confirmed that acetaminophen may not be an appropriate marker of solid-phase gastric emptying. The acetaminophen gastric emptying test should be applied only for the assessment of liquid-phase emptying in animals.
Objective—To compare the rate of gastric emptying
of a semisolid meal by use of the carbon 13-labeled
octanoic acid breath test (13C-OBT) and gastric emptying
ultrasonography (GEU) in dogs.
Animals—10 healthy dogs.
Procedure—Food was withheld from dogs for 12 hours
before ingestion of a test meal (bread, egg, and
skimmed milk) containing 13C-octanoic acid. The gastric
antrum was visualized by use of a 6.5-MHz microconvex
transducer, and the area of the ellipse defined by the
craniocaudal and ventrodorsal diameters of the stomach
was measured. Samples of expired air and antral
images were obtained 30 minutes before ingestion of
the test meal and then every 15 minutes for 4 hours and
every 30 minutes for a further 2 hours. The half-dose
recovery time with the 13C-OBT (t½[BT]) and the gastric
half emtying time withGEU (t50%[GEU]) was calculated.
Results—Mean ± SD values for the t½(BT) and
t50%(GEU) were 3.44 ± 0.48 hours and 1.89 ± 0.78
hours, respectively. A significant correlation was
detected between the t½(BT) and t50%(GEU), although
there was a large (1.55 hours) mean difference
between these indices.
Conclusions and Clinical Relevance—Results indicated
that there was a correlation between the rate of
solid-phase gastric emptying assessed by use of GEU
and the 13C-OBT in dogs. Gastric emptying ultrasonography
may be a useful, noninvasive method for
assessment of the rate of solid-phase gastric emptying
in dogs. (Am J Vet Res 2004;65:1557–1562)
Objective—To assess the 13C-octanoic acid breath
test for determining gastric emptying in dogs.
Animals—6 healthy adult dogs.
Procedure—Food was withheld for 12 hours before
each test. Expired air was collected 30 minutes and
immediately before each test and at frequent intervals
thereafter for 6 hours. Concentration of 13CO2 in
expired air was determined by use of continuous-flow
isotope-ratio mass spectrometry. Basal concentration
of 13CO2 was measured in dogs that were not fed a
test meal. Effects of the standard unlabeled test meal
on basal concentration of 13CO2 were then assessed.
The optimum dose of substrate was determined by
measuring 13CO2 concentration after ingestion of the
standard test meal containing 50 or 100 mg of 13C-octanoic acid, whereas effect of energy density of
the test meal on gastric emptying was determined
after ingestion of the standard or high-energy labeled
test meal. Gastric emptying coefficient (GEC), time to
peak 13CO2 concentration (tmax), and half-dose recovery
time (t½) were calculated.
Results—Basal concentration of 13CO2 in expired air
was not significantly affected by ingestion of the unlabeled
test meal. However, 13CO2 concentration significantly
increased in a dose-dependent manner after
ingestion of the labeled meal. Gastric emptying coefficient,
tmax, and t½ were significantly different
between dogs fed the standard and high-energy test
meals, indicating that ingestion of a high-energy meal
delays gastric emptying.
Conclusions and Clinical Relevance—The
13C-octanoic acid breath test may be a useful noninvasive
and nonradioactive method for assessment of gastric
emptying in dogs. (Am J Vet Res 2001;62:1939–1944)