CEPHALEXIN CONCENTRATIONS IN RADICULAR GRANULOMA FOLLOWING A SINGLE ORAL-ADMINISTRATION OF 250-MG OR 500-MG CEPHALEXIN

1. Cephalexin concentrations in radicular granuloma and serum followin g a single oral administration of 250- or 500-mg cephalexin were measu red by a paper disk method. 2. The highest concentration of cephalexin in radicular granuloma following administration of 250-mg cephalexin to nonfasting patients was observed at 2 hr, and was 1.62 mu g/g. The mean cephalexin concentration ratio of radicular granuloma/serum at 2 hr was 0.35. 3. The highest concentrations of cephalexin in radicular granuloma following administration of 500-mg cephalexin to nonfasting and fasting patients occurred at 2 and 1.5 hr, and was 3.35 and 3.42 m u g/g, respectively. Mean cephalexin concentration ratios of radicular granuloma/serum at 2 and 1.5 hr were 0.32 and 0.30, respectively. 4. All mean cephalexin concentrations in radicular granuloma following ad ministration of 500-mg cephalexin to both fasting and nonfasting patie nts exceeded MIC for 90% (2 mu g/ml) of clinically isolated strains of alpha-hemolytic streptococci. However, those concentrations obtained by 250-mg cephalexin did not exceed it.