Biomaterial Database

Effects of chronic oral administration on the disposition of laevodopa and its major metabolites in the plasma of the rat. 1975

L K Cheng, and H L Fung

1. Plasma levels of total radioactivity , unchanged laevodopa, catecholamines, 3-O-methyldopa and non-amino phenolic acids were measured in rats treated orally with [3H]laevodopa (100 mg/kg, 100 muCi/kg) for different periods of time. 2. Chronic oral administration of laevodopa for two months significantly delayed the appearance of peak plasma levels and decreased the overall plasma concentrations of the unchanged drug as compared to controls. The extent of absorption of an oral dose of [3H]laevodopa was not significantly impaired on chronic treatment and/or ageing. The decrease in the levels of unchanged laevodopa appeared to be due to an increase in the apparent volumes of distribution of the drug and its metabolites upon ageing. 3. The plasma levels of the catecholamine metabolite fraction, which included dopamine, noradrenaline, etc., were much higher in chronically dosed animals. 4. These findings may be relevant in the understanding of such clinical observations as decreasing therapeutic effects and increasing toxicity after long-term laevodopa treatment in human patients.

UI	MeSH Term	Description	Entries
D007980	Levodopa	The naturally occurring form of DIHYDROXYPHENYLALANINE and the immediate precursor of DOPAMINE. Unlike dopamine itself, it can be taken orally and crosses the blood-brain barrier. It is rapidly taken up by dopaminergic neurons and converted to DOPAMINE. It is used for the treatment of PARKINSONIAN DISORDERS and is usually given with agents that inhibit its conversion to dopamine outside of the central nervous system.	L-Dopa,3-Hydroxy-L-tyrosine,Dopaflex,Dopar,L-3,4-Dihydroxyphenylalanine,Larodopa,Levopa,3 Hydroxy L tyrosine,L 3,4 Dihydroxyphenylalanine,L Dopa
D008297	Male		Males
D008750	Methyldopa	An alpha-2 adrenergic agonist that has both central and peripheral nervous system effects. Its primary clinical use is as an antihypertensive agent.	Methyldopate,alpha-Methyldopa,Aldomet,Alphamethyldopa,Apo-Methyldopa,Dopamet,Dopegit,Dopegyt,Dopergit,Hydopa,Meldopa,Nu-Medopa,Sembrina,alpha-Methyl-L-Dopa,Apo Methyldopa,Nu Medopa,alpha Methyl L Dopa,alpha Methyldopa
D002395	Catecholamines	A general class of ortho-dihydroxyphenylalkylamines derived from TYROSINE.	Catecholamine,Sympathin,Sympathins
D006719	Homovanillic Acid	A 3-O-methyl ETHER of (3,4-dihydroxyphenyl)acetic acid.	3-Methoxy-4-Hydroxyphenylacetic Acid,4-Hydroxy-3-Methoxyphenylacetic Acid,3 Methoxy 4 Hydroxyphenylacetic Acid,4 Hydroxy 3 Methoxyphenylacetic Acid,Acid, 3-Methoxy-4-Hydroxyphenylacetic,Acid, 4-Hydroxy-3-Methoxyphenylacetic,Acid, Homovanillic
D000284	Administration, Oral	The giving of drugs, chemicals, or other substances by mouth.	Drug Administration, Oral,Administration, Oral Drug,Oral Administration,Oral Drug Administration,Administrations, Oral,Administrations, Oral Drug,Drug Administrations, Oral,Oral Administrations,Oral Drug Administrations
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D014642	Vanilmandelic Acid	A 3-O-methyl ether of 3,4-dihydroxymandelic acid. It is an end-stage metabolite of CATECHOLAMINES; EPINEPHRINE; and NOREPINEPHRINE.	Methoxyhydroxymandelic Acid,4-Hydroxy-3-Methoxymandelic Acid,Vanillylmandelic Acid,4 Hydroxy 3 Methoxymandelic Acid,Acid, 4-Hydroxy-3-Methoxymandelic,Acid, Methoxyhydroxymandelic,Acid, Vanillylmandelic,Acid, Vanilmandelic
D015102	3,4-Dihydroxyphenylacetic Acid	A deaminated metabolite of LEVODOPA.	DOPAC,Homoprotocatechuic Acid,3,4-Dihydroxyphenylacetic Acid, Monosodium Salt,3,4 Dihydroxyphenylacetic Acid