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Absorption and decomposition of potassium‐ 35 S‐phenoxymethyl penicillin
Author(s) -
Hellström Kjell,
Rosén Anders,
Swahn Åke
Publication year - 1974
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1974165part1826
Subject(s) - urine , metabolite , absorption (acoustics) , excretion , chemistry , penicillin , drug , gastrointestinal tract , antibiotics , pharmacokinetics , potassium , pharmacology , decomposition , chromatography , medicine , biochemistry , organic chemistry , physics , acoustics
As evidenced by the nonabsorbable marker included in the test solution, about 45% of the radioactivity given orally as 35 S‐phenoxymethyl penicillin (PcV) was absorbed in the upper part of the gastrointestinal tract of healthy men. In gastrointestinal aspirates, about 10% of 35 S‐PCV had been degraded to material tentatively identified as the penicilloic acid that was poorly absorbed. There was no evidence of biliary excretion of radioactivity, and it appeared that the excretion of label in the urine (mean, 49%) essentially represented the total uptake of intact drug. The cumulative recovery of 35 S‐PCV in “intact” form in the urine averaged about 30% of the dose. Comparisons of the total concentrations of PcV and its metabolite(s) in the plasma (radioassay) and that of the intact drug demonstrated the presence of substantial amounts of microbiologically inactive metabolite(s). The half‐life of this material was considerably longer than that reported for PcV. It is concluded that the incomplete recovery of orally administered PcV in the urine is due not only to a poor absorption but also to decomposition of the drug before as well as after absorption.