Y. Nagatsu, K. Takagi
Jul 1, 1985
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Influential Citations
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Journal
Journal of Labelled Compounds and Radiopharmaceuticals
Abstract
In order to study the metabolic fate of 3-isobutyryl-2-isopropylpyrazolo [1, 5-a]pyridine (I, KC-404: antiasthmatic agent) in experimental animals and humans, the synthesis of I labeled with carbon-14 or deuterium was investigated. Carbon-14 labeled I was obtained from 5 mCi of isobutyric acid-1-14C sodium salt with a 67.7% yield. Its specific activity was 24.7 mCi/mg. Deuterium labeled I was synthesized from pyridine-d5 with a 17.8% yield, which resulted in about 50% replacement of deuterium with hydrogen at the position 7 in I. The release of deuterium apparently did not occur on GC-MS. The mixture of deuterium labeled I and unlabeled I (2:1 mole ratio) supplied nearly the same intensity of triplet ions (ion clusters) used for identification of I and its metabolites.