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Morphine metabolism in man: Effect of aspirin
Author(s) -
Brunk S. Fred,
Delle Margrieta,
Wilson William R.
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/cpt1974153283
Subject(s) - morphine , aspirin , glucuronide , chemistry , urine , pharmacology , metabolism , urinary system , endocrinology , medicine , biochemistry
Morphine metabolism was studied in 12 normal subjects. Six were studied before and while receiving aspirin, 0.6 gm every 6 hours, and 6 were studied before and while receiving aspirin, 1.2 gm every 6 hours. The study was performed to determine whether aspirin decreases the conjugation of morphine with glucuronide. When aspirin and morphine were given together, plasma levels of free morphine were lowered slightly; after the high dosage of aspirin, the plasma levels of conjugated morphine were slightly higher than control. The urinary excretion of conjugated morphine was decreased by aspirin. Total radioactivity excreted in the urine was similar in all studies. These findings can best be explained by changes in renal clearance of free and conjugated morphine. The clearance of free morphine (organic calion system) tends to be either unchanged or increased by aspirin while the clearance of conjugated morphine (organic anion system) is decreased. These changes appear to be sufficient to explain the changes in plasma and urinary ffee and conjugated morphine levels. Aspirin, at these dosage levels, therefore, does not decrease the conjugation of morphine with glucuronide and does not affect N‐demethylation.