薬物水溶液の凍結相における電気伝導度変化(第1報)共晶温度および非晶凍結時の崩壊温度の測定

概要

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Changes in the electrical conductivity (conductivity) of various drugs in aqueous frozen phase were measured at increasing temperature and logarithm of the conductivity was plotted against reciprocal of absolute temperature. The change in the conductivity after the frozen solution being led to its eutectic state by either annealing or seeding was examined to obtain eutectic temperature. Investigation disclosed the relationship between collapse temperature (cp) observed during freeze-drying and the change in the conductivity observed in the process of amorphous freezing. Ascorbic acid, xylose, etc., when subjected to amorphous freezing, were found to show a bend, while cephalothin sodium, cephamandol sodium, etc. exhibited a sharp increase in the conductivity at individual cp. When the curve shows a bend, cp varies with the concentration of drug : this dependence of cp upon concentration was not observed in cases when a sharp increase in the conductivity can be observed. The sharp increase in the conductivity can be correlated with an endothermic peak or DSC. Generation of a sharp increase in the conductivity is interpreted to indicate glass transition accompanied with heat absorption in amorphous-frozen state of an aqueous drug solution.
公益社団法人日本薬学会の論文
1984-09-25