Pharmacokinetic study of single and multiple oral administration of glutamine in healthy Beagles.

Glutamine is an amino acid that is mainly used for the treatment of gastrointestinal diseases in clinic, but there is a lack of such medicine in veterinary clinic, and its research in dogs has never been seen. This study aimed to investigate the pharmacokinetics of single and multiple administration of glutamine (Gln) tablets in Beagles. Twenty-four healthy Beagles were randomly selected for the pharmacokinetic study of a single dose of low (120 mg/kg), medium (240 mg/kg), and high (360 mg/kg) Gln tablets. After 7 days of washout period, six Beagles in the medium group were selected for a multiple-dose pharmacokinetic study, 240 mg/kg twice a day for 7 days. The Gln concentration in plasma was determined by a validated UPLC-MS/MS method. The results of single oral administration of different doses of Gln tablets showed that Cmax, AUC0→t, AUC0→∝ had a certain linear relationship with the dosage. T-tests were performed for single and multiple administration of Tmax, Cmax, t1/2λz, AUC0→t, and AUC0→∝, and the results showed no significant differences (p > 0.05). Therefore, Gln tablets were absorbed quickly by oral administration, and there was no accumulation in Beagles after 7 days of administration.

A validated UPLC-MS/MS method for quantification of glutamine in plasma and pharmacokinetic study of oral glutamine tablets in healthy Beagles.

This study aimed to clarify the laws of glutamine tablets absorption, distribution, and metabolism in Beagles and to provide a basis for formulating dosing regimens. Twelve healthy Beagles were enrolled the absolute bioavailability study with a crossover design . Glutamine tablets (240 mg/kg b.w.) or glutamine sterile solution (60 mg/kg b.w.) were administered. A method for the determination of glutamine in Beagles' plasma by UPLC-MS/MS was established, with high sensitivity, specificity, and simplicity. Based on the study of endogenous glutamine concentration, the mean concentration of the four time points before drug administration was selected as the background concentration of glutamine. Pharmacokinetic parameters were calculated by non-compartment model. The Cmax of glutamine was 136.11 ± 72.51 µg/ml, Tmax was 0.85 ± 0.29 h, and t1/2λz was 0.42 ± 0.27 h after oral administration. The AUC0-t of glutamine was 116.30 ± 75.15 h·µg/ml vs. 44.55 ± 22.48 h·µg/ml following oral and IV administration, respectively, with an absolute bioavailability of 64.74% ± 19.18%. The results showed glutamine was quickly absorbed and eliminated in Beagles with high bioavailability. Therefore, glutamine is suitable to be prepared as oral tablets and recommended to shorten the dosing interval.