Aly ZH
Studies on caffeine and theobromine in sheep. II. Caffeine.

Zentralbl Veterinarmed A, 28(9-10): 701-710, 1981
ISSN: 0514-7158 Zentralblatt für Veterinärmedizin - Reihe A / Journal of Veterinary Medicine - Series A (PubMed)

Abstract
Caffeine was given intravenously to 3 groups of 6 sheep in doses of 25, 2.5 and 1.8 mg/kg body weight, respectively. Thin layer chromatography was used for the analysis of caffeine and its metabolites. The results showed: 25 mg/kg body weight induced increase of motility and slight tremor during the first 3 hours after injection; an increase in urine volume was observed directly after application of 25 mg/kg, with return to normal within 2 days; all doses of caffeine resulted in comparable plasma concentration curves with a maximum after half an hour, followed by a gradual decrease; the plasma half-life of caffeine is related to the dose and was found to be 3.6 and 7.8 hours after a dose of 1.8 and 25 mg/kg b.w., respectively; the percentage of excreted unchanged caffeine in urine in the period from 0 to 48 hours was not related to the dose and was 7.12+/-1.42; 7.9+/-1.9 and 6.89+/-1.48% for doses of 25, 2.5 and 1.8 mg, respectively; the smallest amount of caffeine excreted in faeces was recorded for the highest doses (1.76+/-0.29; 4.76+/-1.52 and 3.75+/-1.43 for doses of 25, 2.5 and 1.8 mg, respectively), because excretion in urine is increased by high caffeine dosage; and in addition to the excretion of unchanged caffeine in urine, 1,7-dimethylxanthine, 7-methyluric acid, theobromine, theophylline and 7-methylxanthine were quantitatively estimated up to 48 hours.