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F Chiba

Publications and source records attributed to F Chiba.

5 recordsLinked to original sources

[Tissue distribution of cefminox in beagle dogs].

A new cephamycin antibiotic, cefminox (MT-141, CMNX), was intravenously infused into Beagle dogs at a dose of 40 mg/kg in order to study it's distribution to various tissues. The following results were obtained. The maximum serum concentration of CMNX observed at the end of the infusion period was 102.3 micrograms/ml, and then the concentration decreased. The biological half-life of CMNX in serum was 37.0 minutes. This half-life was similar to the results of previous studies with Beagle dogs and rabbits. The maximum concentrations in tissues and body fluids were highest in B-bile followed by kidney, urinary bladder, serum, liver, vagina, uterus, pericardiac fluid, trachea, ovary, lung, gallbladder, parotid gland, heart, tonsil, thymus, spleen, pancreas, aqueous humor and cerebrospinal fluid, in that order and not detected in brain. The maximum concentrations in gallbladder, B-bile, pericardiac fluid and cerebrospinal fluid were found at 1-2 hours after administration. In other tissues and body fluids, they were obtained at the end of the infusion period. The area under the tissue concentration curve (AUC) was highest in the urinary bladder followed by the kidney, vagina, liver, uterus, gallbladder, trachea, ovary and lung, in that order. These results suggest that CMNX is useful for various infectious diseases in these tissues. The pharmacokinetic parameter (K1i/K2i) derived from serum and tissue concentrations using the deconvolution method well correlated to maximum tissue concentrations.

Animals↗

A novel method to predict the elimination half-lives and the renal excretion mechanisms of cephalosporins.

A novel method was proposed to predict the elimination half-lives of cephalosporins from plasma protein binding (unbound fraction, f) and fraction of the dose excreted into urine (f*) on the basis of the following four assumptions. 1) The drug is only distributed to the extracellular fluid, 2) the bound fraction of the drug in plasma is independent of the plasma drug concentration, 3) the binding protein of the drug is albumin, 4) the unbound drug in plasma is excreted by the glomerular filtration and the contribution of active secretion and reabsorption is negligible. The VSS's and t1/2 beta's of MT-141, one of cephalosporins, in rabbits, dogs and healthy human subjects were well predicted, whereas in rats, the prediction of the both values was failed. The t1/2 beta's of various cephalosporins in healthy subjects were calculated from f and f*, in reasonably good agreement with the observed ones, except for some cephalosporins which have been reported to be secreted actively in the renal tubules. Thus, the comparison of the calculated t1/2 beta's with the observed ones makes it possible to presume the renal excretion mechanism. Moreover, this method will be applicable to other drugs which satisfy the above four assumptions.

Animals↗