Cefaloglycin

The article deals with experimental determination of ionization constants and solubility for the compounds (target products, initial β-lactams, acylating agents and by-products) involved in enzymatic synthesis of some therapeutically used aminopenicillins and aminocephalosporins, namely ampicillin, amoxicillin, cephalexin, cephadroxil, cephaloglycin, cefaclor, cefprozil, cefatrizine. Methodology of investigations and the evaluation of experimental data for the determination of ionization constants and solubility of the different type electrolytes are presented. Applications of the methods based on acid-base potentiometric titration and on determination of solubility-pH dependence of assayed substances are discussed. The original data on ionization constants and solubility of amoxicillin, cefprozil, cefatrizine, cephadroxil and initial β-lactams for production of cefaclor, cefprozil and cefatrizine, as well as solubility of by-product D-(-)-p-hydroxyphenylglycine are presented.

The nephrotoxic beta-lactam antibiotics (beta-lactams) cephaloridine, cephaloglycin and imipenem are toxic to the mitochondrial transport and (secondarily) oxidation of succinate and other dicarboxylic substrates. However, compared to cephaloglycin, cephaloridine is minimally toxic to the mitochondrial uptake and uncoupled oxidation of the short-chain fatty anion butyrate. Further studies were therefore done to compare the early effects of nephrotoxic doses (300 mg/kg body weight) of imipenem, cephaloridine and cephaloglycin on the mitochondrial metabolism of three important monocarboxylic substrates, butyrate, valerate and pyruvate, in rabbit renal cortex. The following was found: 1) imipenen reduces the oxidation of all three monocarboxylates, within 0.5 to 1 hr after administration. 2) The respiratory toxicity of cephaloglycin is essentially the same as that of imipenem with all three substrates. 3) cephaloridine causes little or no toxicity to pyruvate or butyrate oxidation and is significantly less toxic than imipenem or cephaloglycin to valerate oxidation.

The fluorescent organic anion fluorescein (FL) accumulates in proximal tubular cells of the kidney during renal secretion. In freshly isolated and permeabilized proximal tubular cells, the uptake was reduced but still sensitive to probenecid, suggesting a concentrative mechanism that is associated with intracellular compartments. Previous studies have shown that one of these compartments may be mitochondrial. In this study, we further investigated the transport characteristics of FL in isolated rat kidney cortex mitochondria. Mitochondrial uptake of 100 microM FL was rapid, with an initial rate of 60 pmol/mg protein.min, and reached equilibrium after 5 min. To characterize the transport system(s) involved, FL uptake was studied in the absence and presence of substrates or inhibitors specific for the various mitochondrial anion carriers. Phenylsuccinate (10 mM), an inhibitor of the alpha-ketoglutarate carrier, reduced uptake significantly with a maximum inhibition of 33% and an inhibitory constant (-log IC(50)) of 4.

The role of an alpha-amino group on interaction with the intestinal and renal peptide carriers (PEPT 1 and PEPT 2, respectively) has been the subject of much investigation. Studies have differed in their conclusions about the role of an alpha-amino group on carrier-mediated absorption. Most studies have used brush-border membrane vesicles or perfused intestinal segments. These techniques enable the determination of membrane uptake and luminal disappearance, respectively, but not transepithelial transport. Transepithelial transport should be more predictive of absorption because it includes basolateral efflux, which could be the rate-limiting process in drug absorption. The objective of this study was to evaluate the influence of an alpha-amino group on PEPT 1-mediated transepithelial transport in Caco-2 cells. The apical-to-basolateral permeability coefficients of cephalosporins with or without a free alpha-amino group were determined in the presence and absence of a pH gradient.