PubMed · 9376934
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F Manresa. 1997. [Resistant pneumococcus].. https://doi.org/10.1016/s0300-2896(15)30560-3
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Cephalosporins with 3-pyazolylpyridinium at C-3 position, which is supposed to exhibit synergic activity of ceftazidime and cefoselis, were synthesized and their antibacterial activity against gram-positive and gram-negative was inspected.
Micellar electrokinetic chromatography (MEKC) was introduced to evaluate the hydrophobicity of cephalosporins (cefpim, cefpirom, cefazolin, ceftazidim, cephradin, cefuroxim, cefotaxim, cephapirin and cephalothin). Partition coefficients of cephalosporins were calculated between a micelle and an aqueous phases from the measurement of the migration time, provided the critical micelle concentration and the phase ratio are known. Thermodynamic quantities such as enthalpy and entropy changes of micellar solubilization were calculated from the temperature dependence on the partition coefficients. Sodium glycodeoxycholate in low-salt aqueous solutions was employed to prepare a micellar solution. Substances for pharmaceutical purposes have to meet several requirements to be well-tolerated. Therefore, they are often derived from naturally occurring ones, e.g., from the bile salts in bile juice. The electrophoretic velocity of a micelle and the phase ratio between the micelle of the glycodeoxycholic acid and the aqueous phase were calculated. Partial specific volumes at different temperatures (from 20 to 45 degrees C) were measured using dynamic light scattering. The logarithm of the partition coefficients and the migration factor in the micellar system were correlated with the logarithm of the 1-octanol-water partition coefficients.
A new electrokinetic chromatographic method was applied to the determination of the partition coefficient between water and micelle for a group of cephalosporins (cefmetazol, cephradin, cefaclor, ceftazidim, cefodizim, cephapirin, cephalothin and ceftriaxon) using sodium dodecyl sulphate as an anionic surfactant in microemulsion and in micellar systems. In the new method, the running buffer contains both the micelles and the drug, and the injected solution contains the same concentration of micelles as the running buffer but not the drug. The mobility of the drug can be measured from a negative peak recorded the chromatogram. The required parameters for the determination of the capacity factor (mu(aq) and /mu(me) are the electrophoretic mobilities of the solutes in the aqueous and the micelle phases, mu(eff) is the effective mobility in the micellar system or in the microemulsion) were measured by the new micellar and microemulsion electrokinetic chromatography technique. Linear log-log relationships were found between both the micelle-water partition coefficient and the capacity factor and the n-octanol-water partition coefficient.