. Therapeutic doses of colistin sulphomethate sodium B.P. (Colomycin), pento‐N sulphomethylpolymyxin B sodium (Thiosporin) and ampicillin B.P. (Penbritin) as well as normal saline have been given to volunteers with normal kidney function.
. A blind crossover technique was used and the effects of the compounds on blood levels and clearances of urea and creatinine studied.
. All four treatments resulted in some changes in the parameters measured but were reversible. The most marked changes were found with pento‐N sulphomethylpolymyxin B sodium and were also associated with severe side‐effects.
. In contrast to penicillins it is established that the process of tubular secretion sensitive to probenecid block plays no part in the renal excretion of polymyxins.