Studies on the Metabolism and Excretion of L-3, 4-Dihydroxyphenylalanine (L-DOPA) in Human Beings by Gas Chromatography

Imai, Kazuhiro; Sugiura, M.; Kubo, Hiroaki; Tamura, Zenzo; Ohya, Kazumi; Tsunakawa, Nobutaka; Hirayama, Keizo; Narabayashi, Hirotaro

doi:10.1248/cpb.20.759

Cited by 10 publications

(1 citation statement)

References 1 publication

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“…In order to determine the total amounts of the metabolites, the acid hydrolysis of their conjugates was first performed by heating the urine samples at 100 °C for 25 min. 26 (2) L-Dopa in the Urine. EDTA (1 mL, 0.1 M) was added to the urine sample and the pH was adjusted to about 6 with 2 N ammonium hydroxide.…”

Section: Methodsmentioning

confidence: 99%

Improved delivery through biological membranes. 4. Prodrugs of L-DOPA

Bodor¹,

Sloan²,

Higuchi³

et al. 1977

J. Med. Chem.

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Various classes of transient derivatives of L-Dopa have been synthesized, systematically protecting one or more of the main sites of metabolism in the molecule: the carboxy function, the amino, and/or the catechol system. The derivatives studied include carboxy esters, phenol esters, amides, peptides, and various combinations of these functions. A number of these derivatives effectively prevent the metabolism of L-Dopa prior to and/or during the absorption process, resulting in a significantly better bioavailability of the drug. In vivo studies using dogs showed up to 2.5-fold increase in L-Dopa blood levels. The metabolism as well as toxicity aspects of the prodrugs is also discussed.

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Section: Methodsmentioning

confidence: 99%

Improved delivery through biological membranes. 4. Prodrugs of L-DOPA

Bodor¹,

Sloan²,

Higuchi³

et al. 1977

J. Med. Chem.

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Dosage form Design for Improvement of Bioavailability of Levodopa II: Bioavailability of Marketed Levodopa Preparations in Dogs and Parkinsonian Patients

Sasahara

Nitanai

Habara

et al. 1980

Journal of Pharmaceutical Sciences

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An improved fluorimetric method for assay of Dopa in urine and tissues and its use for determination of urinary Dopa, at endogenous level, in different species

Cottet-Émard¹,

Peyrin²

1977

J. Neural Transmission

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An optimized fluorimetric method is presented which permits the analysis of DOPA in urine or tissues, at endogenous levels. A wide variety of eluates can be analyzed by applying the manual or the automated schedule. The automated manifold, developed for DOPA assay, may be used to estimate norepinephrine (NE) in other samples, by only changing the nature of reagents to be pumped. Amounts of DOPA as low as 0.3 ng/ml of eluate can be detected. Determinations of endogenous DOPA are reported in urinary samples of Humans, Rats, Dogs and Sheeps, and in brain of Rats. The pattern of changes in DOPA urinary excretion has been investigated as a function of time in Rats. Dietary influences have been studied in Man, Rat and Dog. It is concluded that the greatest part of free and conjugated DOPA excreted in urine of these animals has an endogenous origin.

show abstract

Studies on the Metabolism and Excretion of L-3, 4-Dihydroxyphenylalanine (L-DOPA) in Human Beings by Gas Chromatography

Cited by 10 publications

References 1 publication

Improved delivery through biological membranes. 4. Prodrugs of L-DOPA

Improved delivery through biological membranes. 4. Prodrugs of L-DOPA

Dosage form Design for Improvement of Bioavailability of Levodopa II: Bioavailability of Marketed Levodopa Preparations in Dogs and Parkinsonian Patients

An improved fluorimetric method for assay of Dopa in urine and tissues and its use for determination of urinary Dopa, at endogenous level, in different species

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