Binding of antibiotics to bovine and ovine serum

The degree of binding of 37 antibiotics to bovine and ovine serum, after treatment at therapeutic doses, was determined by equilibrium dialysis and ultrafiltration methods. In general, binding values obtained by the two methods were comparable. The extent of binding varied from 0% for cephaloridine and kanamycin to >95% for novobiocin and fusidic acid. Of the 37 drugs studied, one-fourth were less than 25% bound, one-fourth were more than 75% bound, and the percentage binding of about half of the antibiotics ranged from 25 to 75%. Animal to animal variations in the extent of binding of a particular antibiotic were very small. The capacity of bovine or ovine serum to bind antibiotics was, with a few exceptions, similar to the reported capacity of human serum. At drug concentration ranges usually achieved during therapy, variations in drug levels in serum did not influence the degree of binding except with cephalexin, lincomycin, clindamycin, and chloramphenicol. With these antibiotics, the extent of binding increased two- to sevenfold with the decrease in drug concentration in serum.

Serum protein binding of the aminoglycoside antibiotics

The binding of four aminoglycoside antibiotics by human serum was investigated under controlled conditions of physiological pH and temperature, by means of an ultrafiltration technique. No serum binding was demonstrable for gentamicin, tobramycin, or kanamycin, whereas streptomycin was 35% bound. Previous conflicting studies are discussed, and some of the pharmacological implications are considered.

Use of a tabletop computer for antibiotic assays

The increasing need for rapid and accurate assay of antimicrobial agents in body fluids requires technical improvement of skills in these areas. A method for using a tabletop computer to simplify and shorten the statistical analysis of the laboratory data obtained by bioassay with the Olivetti Underwood Programma 101 has been developed so that a secretary or laboratory helper can rapidly develop the standard curves for each day's assays.

Specific assay of aminoglycosidic- or polymyxin-type antibiotics present in human sera in combination with cephalosporins

Monitoring of serum concentrations of aminoglycosidic or polymyxin antibiotics when administered concurrently with cephalosporins or penicillins requires a special assay technique. Selective enzymatic degradation of the beta-lactam antibiotic from the serum specimen allows subsequent assay of the antibiotic being monitored. This report gives details of a simple procedure for laboratory production of a crude enzyme capable of degrading cephalosporins or penicillins. An assay procedure for quantitating aminoglycosidic or polymyxin antibiotics after enzymatic degradation of a coexisting beta-lactam antibiotic is described.