Fundamental and clinical investigations with a new Cephalosporin C derivative, Cephalothin (CET) were performed with the following results:
1) In vitro antibacterial activity: The minimal inhibitory concentration of CET was measured by an agar plate dilution method. The MIC of CET against 80 strains of coagulase positive staphylococcus isolated from otorrhea was distributed over a range of ≤0.19 to 6.25 mcg/ml, with a peak being observed particulary at ≤0.19 mcg/ml.
2) Concentration in blood: The average maximal level reached 10.1 mcg/ml, 30 minutes after a single intramuscular injection of 500 mg to healthy adults, and the level was still 0.1 mcg/ml 6 hours after the injection.
3) Concentration in tissues: CET activity was demonstrable at the concentration of 0.4 to 0.7 mcg/g in a human palatine tonsil and mucous membrane from the maxillary sinus one hour after the intramuscular injection of 500 mg. Further, the serum concentration of CET was between 6.8 to 7.1 mcg/ml.
4) The results of treatment with intramuscular injection of CET in 30 cases of infections were excellent in 18 cases, good in 10 cases and fair in 2 cases. When the cases in which it was excellent and good were considered together, good results were obtained in 30 cases, or 93 per cent.
5) Side effect: No side effect was shown with the intramuscular injection of CET. An examination of hepatic function, electrolytes and auditory acuity before and after the injection showed no significant disturbance.