Pharmacokinetic and Clinical Studies with Caffeine

Abstract

A preliminary study was carried out to investigate the pharmacokinetics
of caffeine. Four healthy adult volunteers each received 200mg, 400mg and 600mg doses of caffeine on separate mornings, having
abstained from food and drink containing methylxanthines for the
previous 24 hours. Blood, saliva and urine samples were taken at intervals during the next 24 hours. Determinations of caffeine,
paraxanthine, theobromine and theophylline concentrations in the
samples were made by high performance liquid chromatography. Caffeine
concentrations in plasma and saliva decreased in a log-linear relationship with time, indicative of first-order kinetics, however this
relationship did not hold for the metabolites. Mean ± standard
deviation plasma caffeine clearance was 1.10 + 0.45ml/min/kg and mean
half-life was 7.1 ± 3.2 hours. Saliva/plasma caffeine concentration ratios showed time dependence with high values initially. Only 2.8 ± 0.5% of the caffeine dose was excreted unchanged in urine...

Date of Award	Oct 1986
Original language	English
Awarding Institution	Aston University