Bogardus J B
J Pharm Sci. 1982 Jan;71(1):105-9. doi: 10.1002/jps.2600710125.
The phase diagram for the binary system nafcillin sodium-water, was determined using differential scanning calorimetry (DSC) and polarized light microscopy. In the temperature range of -20-30 degrees, three crystalline forms and an amphiphilic liquid crystalline phase were detected. The stable crystalline form of nafcillin sodium (form alpha) and water exhibit a eutectic mixture containing 28% drug (w/w) at -1 degrees. In more dilute solutions a lower temperature eutectic (-5 degrees) occurs. The composition and form of nafcillin sodium in this eutectic are not known. The form -5 degrees eutectic was found to be metastable above 28% concentration and converted to form alpha. Two other crystalline forms were observed at 9 degrees (form beta) and 22 degrees (form gamma) at concentrations above 40%. The crystalline forms could not be further characterized due to their transient nature and existence in highly concentrated mixtures. A lamellar mesophase is present near ambient temperature in mixtures containing more than 55% nafcillin sodium. The phase equilibria were highly susceptible to supercooling. Temperature cycling methods were devised which gave reproducible DSC data and allowed construction of the phase diagram.
使用差示扫描量热法（DSC）和偏光显微镜确定了二元体系萘夫西林钠 - 水的相图。在 -20至30摄氏度的温度范围内，检测到三种晶型和一种两亲性液晶相。萘夫西林钠的稳定晶型（α型）和水在 -1摄氏度时形成含有28%药物（w/w）的低共熔混合物。在更稀的溶液中会出现更低温度的低共熔物（-5摄氏度）。该低共熔物中萘夫西林钠的组成和晶型未知。发现 -5摄氏度的低共熔物在浓度高于28%时是亚稳的，并会转变为α型。在浓度高于40%时，在9摄氏度（β型）和22摄氏度（γ型）观察到另外两种晶型。由于这些晶型的瞬态性质以及它们存在于高浓度混合物中，无法进一步对其进行表征。在含有超过55%萘夫西林钠的混合物中，接近室温时存在层状中间相。相平衡对过冷高度敏感。设计了温度循环方法，可得到可重复的DSC数据并能构建相图。
