1) Tissue concentration of Josamycin (JM) in rats:
a) Recovery from tissue emulsions: Recovery of added JM in vitro from tissue emulsions, especially from liver emulsion, was very poor. Other macrolides were not so inact i v ated by emulsions as JM, while carbomycin was in activated similarly to JM.
b) Distribution of JM into rat organs: Concentrations of JM in organs (corrected by in vitro recovery rate) after oral administration in dose of 250 mg per kg were generally very l o w, similarly to concentration of carbomycin, which was previously reported.
2) Biliary excretion of JM in rabbits: Intravenously injected JM in dos e of 20 mg per kg was excreted into bile in markedly higher concentration than serum level. 1-2 % of the administered JM was recovered from bile i n 2 to 2. 5 hours.
3) Blood level and urinary recovery in a human adult: Blood level of JM in a human adult after single o r al dosage of 600 mg was found to be very low; i. e. 0 mcg/ml (1 hr. ), 0. 34 (2 hrs) and O. 3 2 (4 hrs). Only O. 6 % was recovered from his u rine in 4 hrs.
4) In vitro sensitivity of staphylococci to JM: In vitro sensitivity of 28 strains of Staphylococcus aureus to JM was examined and compared with the sensitivity of the same strains to other antibiotics, i. e. spiramycin, olean d omycin, triacetyl-oleandomycin, erythromycin, tetracycline, doxycycline, lincomycin, clinimyc in, kanamycin and kanendoamycin. Generally speaking, the sensitivity of staphylococci to JM was qui t e similar to that to triacetyl-oleandomycin, higher than that to spiramycin, but lower than those t o the other antibiotics.
5) Clinical trials: Five cases of b ronchitis, pneumonia or tonsillitis were treated with oral JM (1200 to 2400 mg daily) administration, which was effective in one case of bronchitis. Nausea was the only adve r s e effect, of which one of the five cases complained.
