Schmidt P C, Herzog R
Department of Pharmaceutical Technology, University of Tübingen, FRG.
Pharm World Sci. 1993 Jun 18;15(3):105-15. doi: 10.1007/BF02113938.
Ten commercially available calcium phosphates used for direct tableting were evaluated. The particle size distributions, powder properties, sorption isotherms and pH values of aqueous slurries were compared. All samples showed good or at least sufficient flowability. Scanning electron micrographs illustrated the different kinds of manufacturing and gave hints on their expectable behaviour under compaction pressure. The sorption isotherms of identical chemical substances, which had been manufactured by different methods, differed strongly. This can be related to their specific surface areas. Most of the hydroxylapatites have large surface areas and can absorb up to more than 15% water at 93% relative humidity. Dibasic calcium phosphate dihydrate was non-hygroscopic and absorbed less than 1% water. With the exception of monobasic calcium phosphate monohydrate all calcium phosphates behaved quite neutral in water. Monobasic calcium phosphate monohydrate can be regarded as a solid acid. Although the calcium phosphates are usually stable substances, the role of crystal water in the case of dibasic calcium phosphate dihydrate and monobasic calcium phosphate monohydrate is problematic due to possible interactions with active ingredients.
对十种市售的用于直接压片的磷酸钙进行了评估。比较了它们的粒度分布、粉末性质、吸附等温线和水性浆料的pH值。所有样品均表现出良好或至少足够的流动性。扫描电子显微镜图像展示了不同的制造方式，并给出了它们在压制压力下预期行为的线索。通过不同方法制造的相同化学物质的吸附等温线差异很大。这可能与它们的比表面积有关。大多数羟基磷灰石具有较大的表面积，在相对湿度为93%时可吸收高达15%以上的水分。磷酸二钙二水合物不吸湿，吸水量小于1%。除磷酸二氢钙一水合物外，所有磷酸钙在水中表现出相当中性的性质。磷酸二氢钙一水合物可被视为固体酸。尽管磷酸钙通常是稳定的物质，但由于可能与活性成分发生相互作用，磷酸二钙二水合物和磷酸二氢钙一水合物中结晶水的作用存在问题。
