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Variations in the bioavailability of thiazinamium methylsulfate
Author(s) -
Jonkman Jan H. G.,
Van Bork L. E.,
Wijsbeek Jaap,
De Zeeuw Rokus A.,
Orie N. G. M.
Publication year - 1977
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/cpt1977214457
Subject(s) - bioavailability , pharmacology , chemistry , medicine
Bioavailability after oral administration of the anticholinergic drug thiazinamium methylsulfate (Multergan), a phenothiazine derivative with a quaternary ammonium group in the moleeule, has been studied in patients and volunteers by measuring the drug concentrations in plasma or the excretion of the parent drug in urine. The relative bioavailability as compared to intramuscular injection seems to be of the order of 10%. Much more of the drug is absorbed, however, but is metabolized during the first liver passage. Moreover, there seems to be a substantial interindividual variation in the bioavailability of the drug. Studies in a group of eight volunteers showed that there is also a substantial intraindividual variation, but its magnitude is smalter than that of the interindividual variation.