Takeda T, Suzuki Y, Inazu K, Sakamoto T, Maekawa H
Yakugaku Zasshi. 1989 Jun;109(6):395-401. doi: 10.1248/yakushi1947.109.6_395.
Cephalothin sodium (CET-Na) in crystals can be obtained by freezing the aqueous solution and subsequent warming at a fixed temperature for facilitating crystallization prior to vacuum application for drying. The product has, however, been found to unavoidably contain traces of the amorphous CET-Na, which causes a rapid color development during storage. By using thermal analysis, differential scanning calorimetry (DSC), electric conductometry, and polarized light cryomicrographic techniques, the solubilities in water, freezing point, eutectic point, and melting behavior of CET-Na in aqueous solution were investigated. The investigation demonstrated that CET-Na in supersaturated aqueous solution is very stable, and that seeding with microcrystalline CET-Na to the supersaturated solution and subsequent cooling of the mixture till its freezing point gives neither any evidence for crystallization nor for growth of the seed crystals. The freeze-drying of CET-Na in the supersaturated solution after seeding has been demonstrated to give crystalline CET-Na containing neither of amorphous nor of quasi-crystalline form.
通过冷冻水溶液并随后在固定温度下升温以促进结晶，然后进行真空干燥，可以得到结晶形式的头孢噻吩钠（CET-Na）。然而，已发现该产品不可避免地含有痕量的无定形CET-Na，这会导致储存期间迅速显色。通过热分析、差示扫描量热法（DSC）、电导率测定法和偏光低温显微技术，研究了CET-Na在水溶液中的溶解度、冰点、共晶点和熔化行为。研究表明，过饱和水溶液中的CET-Na非常稳定，向过饱和溶液中加入微晶CET-Na晶种，然后将混合物冷却至其冰点，既没有结晶的迹象，也没有晶种生长的迹象。已证明，在接种后对过饱和溶液中的CET-Na进行冷冻干燥，可得到既不含有无定形也不含有准晶形式的结晶CET-Na。
