Determination of abomasal emptying rate in suckling calves by use of nuclear scintigraphy and acetaminophen absorption

Abstract

Abomasal emptying rate is best determined in healthy suckling calves by use of Siegel's modified power exponential equation to model the scintigraphic data. Pharmacokinetic calculation of Tmax from the acetaminophen absorption curve provides an alternative method for determining abomasal emptying rate in healthy suckling calves that is accurate, inexpensive, practical, and safe. However, it is unclear whether diarrhea would alter the acetaminophen absorption curve in calves.

Effect of Orally Administered Cisapride, Bethanechol, and Erythromycin on the Apparent Efficiency of Colostral IgG Absorption in Neonatal Holstein‐Friesian Calves

“…Oral administration, instead of parenteral administration, was selected for investigation to develop a practical treatment protocol for dairy producers and to minimize potential tissue inflammation or prolonged withdrawal times for slaughter related to intramuscular or subcutaneous injections. Three liter of pooled colostrum was thawed at 37°C in a water bath and acetaminophen (50 mg/kg BW) added to the colostrum; acetaminophen was added to colostrum because it provides a well described and validated method to estimate abomasal emptying rate in milk‐fed calves 25, 26. Calves were administered colostrum 30 minutes after receiving their assigned treatment by permitting the calf to suckle.…”

“…Abomasal emptying rate was measured using acetaminophen and glucose absorption techniques as previously described 25, 26. Venous blood samples for determination of plasma acetaminophen and glucose concentrations were obtained at 0, 15, 30, 45, 60, 90, 120, 180, 210, 240, 300, 360, 420, and 480 minutes (start of suckling was designated as time 0 minute) in a similar method to the samples obtained to measure plasma IgG concentration.…”

“…Actual maximal plasma concentration ( C max ) and actual T max were derived from a plot of the plasma acetaminophen concentration‐versus‐time data. The first derivative of Siegel's modified power exponential formula was used to model the acetaminophen time curve 25, 26. The equation was derived from the fact that the acetaminophen concentration‐versus‐time curve represented as a cumulative dose curve is an inverse analog of the scintigraphic curve with the following equation: C ( t ) =  m  ×  k  × β × e − k × t  × (1 − e − k × t ) β−1 , where C ( t ) is the acetaminophen concentration in plasma at a specified time point, t is the time, m [unit (μg/mL) × minutes] is the area under the acetaminophen concentration‐time curve when time is infinite, k (min −1 ) is an estimate of the rate constant for abomasal emptying, β is a constant that provides an estimate of the duration of the lag phase before an exponential rate of emptying is reached, and e is the natural logarithm.…”

“…The equation was derived from the fact that the acetaminophen concentration‐versus‐time curve represented as a cumulative dose curve is an inverse analog of the scintigraphic curve with the following equation: C ( t ) =  m  ×  k  × β × e − k × t  × (1 − e − k × t ) β−1 , where C ( t ) is the acetaminophen concentration in plasma at a specified time point, t is the time, m [unit (μg/mL) × minutes] is the area under the acetaminophen concentration‐time curve when time is infinite, k (min −1 ) is an estimate of the rate constant for abomasal emptying, β is a constant that provides an estimate of the duration of the lag phase before an exponential rate of emptying is reached, and e is the natural logarithm. Nonlinear regression (PROC NLIN)10 was used to estimate values for m , k , and β as described 25. Values for model C max and model T max were obtained by fitting the estimated values for k , β, and m in the nonlinear equation to the cumulative dose curve equation for acetaminophen.…”

Effect of tulathromycin on abomasal emptying rate in healthy lactating goats

“…Plasma was thawed at approximately at 25 • C and analyzed spectrophotometrically by use of a colorimetric nitration assay as described (Marshall et al, 2005). The maximum observed plasma concentration (Actual Cmax) and time of maximum observed plasma concentration (Actual Tmax) were obtained from a plot of the plasma acetaminophen concentration -time data.…”