Effect of cephaloridine on human chromosomes in vitro in lymphocyte cultures.

Cephaloridine is a semi-synthetic broad-spectrum bactericidal antibiotic derived from cephalosporin C. The drug was tested for its clastogenic effects on human chromosomes in vitro at various concentrations and for various periods of treatment (24, 48, 72 h) in 72-h lymphocyte cultures. 2 concentrations of the drug used in the tests (20 and 60 micrograms/ml) were similar to those found in the plasma of individuals after receipt of therapeutic doses of 500 mg and 2 g, respectively. 2 other concentrations tested were either below (10 micrograms/ml) or above (120 micrograms/ml) the plasma level. Control cultures were set up simultaneously for each batch of experimental cultures. The aberration frequency was increased with increasing concentration of the drug, irrespective of the duration of the exposure. In other words, there was a dose-effect relationship. No increase in chromosomal aberrations was observed with lower doses of 10 and 20 micrograms/ml. Significant increases were seen with higher doses of 60 and 120 micrograms/ml. Aberrations were mostly of the chromatid type. The results show that cephaloridine is clastogenic at the upper levels of permissible therapeutic doses.