[Detection of antibiotics in biological materials for purposes of toxicologic analysis. II. Detection of tetracyclines in biological materials].

A method of demonstration of tetracycline antibiotics elaborated as a model was used in toxicological practice. Urines of patients were analyzed after therapeutic doses and after large doses taken with suicidal intentions. At the same time, also excretion of these antibiotics from the organism was investigated. All antibiotics under study were found in the original form; in tetracycline other substances, identified as 4-epitetracycline and 4-epianhydrotetracycline, regularly appeared. A question is discussed whether these substances can be considered to be real metabolites or only products of epimerization. The importance of 4-epianhydrotetracycline for analytical purpose and interpretation of the finding is pointed out.