PMID: 7264915Jul 1, 1981

Dosage form design for improvement of bioavailability of levodopa IV: Possible causes of low bioavailability of oral levodopa in dogs

Journal of Pharmaceutical Sciences
K SasaharaE Nakajima

Abstract

Several potential mechanisms for reduced levodopa bioavailability following oral administration to dogs and humans were investigated by studying the influence of the administration route on plasma levodopa levels after intravenous, hepatoportal, and duodenal administrations to dogs. The observed average areas under the plasma concentration-time curves (AUC) of levodopa following hepatoportal injection and intravenous injection were virtually identical; but following duodenal administration a decrease in the AUC of levodopa was observed with a concomitant increase in the AUC of total dopamine. The possible involvement of intestinal microorganisms in levodopa metabolism was explored in dogs that had been administered a combination of paromomycin and kanamycin to reduce intestinal microflora. Similar patterns of plasma level profiles and urinary excretion were observed between control and treated dogs. As measured by the release of [14C]carbon dioxide from [14C]levodopa, the distribution of levodopa decarboxylase enzyme activity in various parts of the intestine was studied in homogenates prepared from isolated intestinal segments of the duodenum and upper, middle, and lower parts of the jejunum and ileum. The jejunum showed the h...Continue Reading

Citations

Jan 1, 1990·Pharmacology & Therapeutics·K F IlettR F Minchin
Jan 1, 1983·European Journal of Clinical Pharmacology·U Gundert-RemyM Da Prada
Apr 23, 2009·Expert Opinion on Drug Delivery·Antonio Di StefanoLaura Serafina Cerasa
Jul 1, 1991·Xenobiotica; the Fate of Foreign Compounds in Biological Systems·T IchihashiH Yamada
Jul 1, 1989·British Journal of Clinical Pharmacology·D R RobertsonC F George
Sep 4, 2016·Translational Research : the Journal of Laboratory and Clinical Medicine·Ian D Wilson, Jeremy K Nicholson
Feb 9, 2008·Molecules : a Journal of Synthetic Chemistry and Natural Product Chemistry·Antonio Di StefanoLaura Serafina Cerasa
Mar 3, 2020·Drug Metabolism Reviews·Yuan XieRong Wang
Nov 1, 1982·Acta Pharmacologica Et Toxicologica·I B Lindén, S Niemi
Nov 5, 2019·Frontiers in Neurology·Sebastiaan P van Kessel, Sahar El Aidy
Oct 21, 2020·BMC Biology·Sebastiaan P van KesselSahar El Aidy

Related Concepts

Metabolic Biotransformation
Gastrointestinal System
Canis familiaris
DOPA decarboxylase
Intestinal Absorption
Intestines
Levopa

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