Pharmacokinetics of caffeine in the oestrogen-implanted ovariectomized ewe

I. Pollard*, S. Williamson, Jeff Downing, Rex Scaramuzzi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The disposition kinetics of caffeine and its metabolites theophylline, theobromine and paraxanthine in the oestrogen-implanted ovariectomized ewe following single intravenous doses of 5, 10, 15 or 20 mg/kg caffeine are described in this paper. Blood was collected at 5, 30 and 60 min, and at 3, 6, 8, 12, 24, 48, 72, 96, 120, 144, 192 and 240 h after dosing. Caffeine concentrations peaked within 30 min of administration but remained in a plateau phase for 3-6 h before declining over a prolonged period of time. For caffeine the mean elimination half-life was calculated to be 47 h. Detectable caffeine concentrations remained for 10 days after administration in all groups. The area under the plasma concentration-time curve (AUG) values were used to compare tissue caffeine exposure and were, approximately, linearly related to dose. Metabolite concentrations were maintained at peak and near peak concentrations for 6-24 h after caffeine administration followed by prolonged elimination, Because of significant species differences in drug elimination rates, it is concluded that the ewe is not a suitable animal model in the clinical context. However, the sheep may well provide insights into caffeine's mechanism of action of relevance to veterinary drug research.

Original languageEnglish
Pages (from-to)113-117
Number of pages5
JournalJournal of Veterinary Pharmacology and Therapeutics
Volume19
Issue number2
DOIs
Publication statusPublished - 1996

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