Abstract
Summary
The absorption and excretion of penicillins X, G, dihydro F and K in humans have been studied in an effort to evaluate the influence of the marked differences in the degrees of binding of these substances by serum protein.
The duration of the serum concentrations afforded by all 4 penicillins after intramuscular injection of 300,000 units to humans were uniform within the limits of the method of assay. During the period when all of the penicillins were present in measurable concentrations there was no difference among the 4 except for the lower peak of penicillin K 15 minutes after injection. Evidence was presented that previous findings of higher and more prolonged serum concentrations of penicillin X, and lower, rapidly disappearing concentrations of penicillin K were artifacts created by differences in the antagonistic action of the serum on penicillin during the actual bioassay procedure. Thus differences in therapeutic effectiveness of the individual penicillins cannot be explained on the basis of differences in height and duration of serum concentrations after equal doses.
Although the total excretion of penicillin K was low, the rate of excretion and the renal clearance suggest that the mechanism of removal of penicillin K by the kidney differs from that observed with the other penicillins.
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