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Variable sensitivity of assay methods of tetracycline and demethylchlortetracycline in human volunteers
Author(s) -
Lichter Edward A.,
Sobel Solomon
Publication year - 1962
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/cpt196235580
Subject(s) - dilution , tetracycline , staphylococcus aureus , bacillus cereus , penicillin , liter , chloramphenicol , antibiotics , absorption (acoustics) , regimen , medicine , chemistry , pharmacology , microbiology and biotechnology , biology , bacteria , materials science , physics , genetics , composite material , thermodynamics
Evaluation of levels of serum antibacterial activity was attempted in 17 normal subjects who took a therapeutically recommended drug regimen of tetracycline or demethylchlortetracycline for 4 days. Microbiologic assay was performed by the tube dilution method with three separate test organisms, and one of these was used in a parallel cup‐plate assay method. The cup‐plate method was found to be more sensitive and more reliable than the tube dilution methods using any of the three organisms. With the dosage regimens used, serum activity accumulation could be shown for DMCT but not for TC. Although individual subject variability in drug absorption may be noted, the average level of serum antibacterial activity was consistently higher with 150 mg. of DMCT four times daily than with 250 mg. of TC four times daily. After 4 days, the difference was found to be Significantly higher in the cup‐plate method and the tube dilution method when Bacillus cereus was the test organism but not in the tube dilution method when streptococcus 98 or staphylococcus 209P was used. We were unable to demonstrate differences in prolongation of serum activity levels after cessation of therapy with these two drugs.