薬物水溶液の凍結相における電気伝導度変化(第2報)セファロチンナトリウム水溶液の凍結状態

概要

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The electrical conductivity (conductivity) of cephalothin sodium (KF) in the aqueous frozen phase was measured at increasing temperature with varying concentrations. Above concentration of 5.0%, a sharp increase in the conductivity was found at -18--22℃. This phenomenon occurred during rewarming after recooling from -5℃ to -50℃. On the other hand, below concentration of 1.5%, the conductivity fell after a rise with increasing temperature. This change of conductivity did not occur during rewarming. A sharp increase in the conductivity was found to correspond to the small endothermic peak of DSC. The concentration dependence of pH of KF in the aqueous solution was measured to demonstrate micelle formation. It may be attributed to the micelle formation that changes of the conductivity of KF in the aqueous frozen phase depend on the concentration of KF. The heat of solution of a drug easily capable of spontaneous nucleation and crystallization in the aqueous frozen phase was compared with that of a drug hardly capable of such a transformation : it was found out that a drug having a low heat of solution hardly transform to crystal owing to spontaneous nucleation. The difficulty of spontaneous transformation to crystal of KF in the aueous frozen phase will certainly be due to its low heat of solution, and the absence of hydrated crystals in spite of the micelle formation.
公益社団法人日本薬学会の論文
1984-09-25