ABSORPTION AND DISPOSITION KINETICS OF RIBOFLAVIN AND ASCORBIC ACID IN HUMANS AS A FUNCTION OF AGE.

Persistent Link:
http://hdl.handle.net/10150/184078
Title:
ABSORPTION AND DISPOSITION KINETICS OF RIBOFLAVIN AND ASCORBIC ACID IN HUMANS AS A FUNCTION OF AGE.
Author:
LOPEZ ANAYA, ARTURO.
Issue Date:
1987
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The objective of this dissertation was to study the disposition and absorption of riboflavin and ascorbic acid in healthy male subjects as a function of age. Deficiencies of these vitamins have been found in the elderly and malabsorption is suspected in this population. Absorption of riboflavin was examined by administration of an oral dose of 200 mg of riboflavin-5'-phosphate (FMN) and disposition was studied following a 30 min constant rate IV infusion of FMN equivalent to 25 mg of riboflavin. Ascorbic acid absorption was examined by administration of a 5 g oral dose and disposition was studied following a 1 g IV dose. Test doses of these vitamins were administered to subjects ranging in age from 33 to 85 years. High performance liquid chromatographic assays were developed for the determination of riboflavin and ascorbic acid in plasma and urine. The method for riboflavin separated FMN and flavin adenine dinucleotide under isocratic conditions. Quantification of the three flavins was achieved by fluorescence detection. The assay system for ascrobic acid used a postcolumn reaction for the fluorometric detection of a dehydroascorbic acid derivative. This method used isoascorbic acid as the internal standard. Finally, similar specificity between a "methoxyaniline" colorimetric method and the chromatographic method was observed for the quantification of ascorbic acid in plasma and urine. Albumin plasma concentration and riboflavin protein binding were decreased with age (p < 0.05). The in vitro stability of ascorbic acid in whole blood and plasma decreased with age (p < 0.05, n = 17). The results of this study indicate no age-related alterations in parameters associated with the gastrointestinal absorption of these vitamins. Increased relative renal excretion of riboflavin with age may explain the deficiency of this vitamin. On the other hand, ascorbic acid deficiency with age may be explained by decreased stability of the vitamin in blood.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Vitamin B2 -- Absorption and adsorption.; Vitamin C -- Absorption and adsorption.; Vitamins -- Metabolism -- Age factors.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Pharmaceutical Sciences; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Mayersohn, Michael B.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleABSORPTION AND DISPOSITION KINETICS OF RIBOFLAVIN AND ASCORBIC ACID IN HUMANS AS A FUNCTION OF AGE.en_US
dc.creatorLOPEZ ANAYA, ARTURO.en_US
dc.contributor.authorLOPEZ ANAYA, ARTURO.en_US
dc.date.issued1987en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe objective of this dissertation was to study the disposition and absorption of riboflavin and ascorbic acid in healthy male subjects as a function of age. Deficiencies of these vitamins have been found in the elderly and malabsorption is suspected in this population. Absorption of riboflavin was examined by administration of an oral dose of 200 mg of riboflavin-5'-phosphate (FMN) and disposition was studied following a 30 min constant rate IV infusion of FMN equivalent to 25 mg of riboflavin. Ascorbic acid absorption was examined by administration of a 5 g oral dose and disposition was studied following a 1 g IV dose. Test doses of these vitamins were administered to subjects ranging in age from 33 to 85 years. High performance liquid chromatographic assays were developed for the determination of riboflavin and ascorbic acid in plasma and urine. The method for riboflavin separated FMN and flavin adenine dinucleotide under isocratic conditions. Quantification of the three flavins was achieved by fluorescence detection. The assay system for ascrobic acid used a postcolumn reaction for the fluorometric detection of a dehydroascorbic acid derivative. This method used isoascorbic acid as the internal standard. Finally, similar specificity between a "methoxyaniline" colorimetric method and the chromatographic method was observed for the quantification of ascorbic acid in plasma and urine. Albumin plasma concentration and riboflavin protein binding were decreased with age (p < 0.05). The in vitro stability of ascorbic acid in whole blood and plasma decreased with age (p < 0.05, n = 17). The results of this study indicate no age-related alterations in parameters associated with the gastrointestinal absorption of these vitamins. Increased relative renal excretion of riboflavin with age may explain the deficiency of this vitamin. On the other hand, ascorbic acid deficiency with age may be explained by decreased stability of the vitamin in blood.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectVitamin B2 -- Absorption and adsorption.en_US
dc.subjectVitamin C -- Absorption and adsorption.en_US
dc.subjectVitamins -- Metabolism -- Age factors.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePharmaceutical Sciencesen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMayersohn, Michael B.en_US
dc.contributor.committeememberCarter, Deanen_US
dc.contributor.committeememberKarol, Michael D.en_US
dc.contributor.committeememberSipes, Glennen_US
dc.contributor.committeememberYalkowsky, Samuelen_US
dc.identifier.proquest8712892en_US
dc.identifier.oclc698473649en_US
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