Evidence for a different metabolic behaviour of cytidine diphosphate choline after oral and intravenous administration to rats

Abstract

Radioactivity plasma decay was studied in rats after intravenous and oral administration of cytidine diphosphate [methyl- 14C] choline at doses of 25 and 300 mg/kg. The kinetics fitted well with a two compartment open model and showed a long lasting elimination phase with a half-life ranging from 2.0 to 2.6 days for the two doses and the two administration routes. Absorption of cytidine diphosphate choline radioactivity was complete after oral treatment with the low dose and accounted for 94.5 % of the dose when 300 mg/kg of cytidine diphosphate [methyl- 14C] choline were administered. However the distribution of radioactivity in tissues, urine and expired air suggest metabolic differences, at least from a quantitative point of view, between the oral and intravenous treatments. In particular, the higher excretion of radioactivity associated with trimethylamine in urine found when cytidine diphosphate [methyl- 14C] choline was given orally, suggest that the compound may be metabolized, at least in part, previous to its gastrointestinal absorption.