Josamycin concentrations in radicular cysts following a single oral administration.

1. Josamycin concentrations in cyst wall (wall) and cyst fluid (fluid) of radicular cyst and serum following a single oral administration of josamycin (600 mg) were assayed by a paper disk method. 2. The mean peak josamycin concentrations in wall, fluid and serum occurred at 1.5, 2 and 1.5 hr, respectively, and were 1.33 micrograms/g, 0.53 and 0.74 micrograms/ml, respectively. 3. The mean concentration ratios of wall/serum, fluid/serum and fluid/wall at the peak times (1.5, 2 and 2 hr) were 1.80, 0.64 and 0.42, respectively. 4. Josamycin concentrations in wall and fluid at the peak time exceeded MIC for 80% for clinically isolated strains of alpha-hemolytic Streptococci.