Rowe R C
J Pharm Pharmacol. 1978 Nov;30(11):669-72. doi: 10.1111/j.2042-7158.1978.tb13361.x.
The effect of some formulation and process variables on the surface appearance of film-coated tablets has been examined by measuring the arithmetic mean roughness, Ra, values across the faces of tablets before and after they were coated with hydroxypropyl methyl-cellulose. For all tablet cores except those that were very porous, film coating resulted in an increasing surface roughness; for very porous cores a decrease was found. Tablets with rough surfaces were produced by coating with low molecular weight grades of the polymer; increasing the polymer molecular weight resulted in a smoother finish with a minimum roughness at intermediate molecular weight grades. Increasing the polymer concentration above 2% w/v caused an increase in roughness as did increasing film thickness to 140 micrometer. There was a minimum in roughness at film thickness of 20 micrometer. The addition of pigment in low concentrations (0--25% v/v) caused a marginal increase in surface roughness but at concentrations above the critical pigment volume concentration, the surfaces were very rough. The results illustrate the potential of the method in the optimization of film formulations and process conditions during product development.
通过测量用羟丙基甲基纤维素包衣前后片剂表面的算术平均粗糙度（Ra）值，研究了一些制剂和工艺变量对薄膜包衣片表面外观的影响。对于除非常多孔的片剂芯之外的所有片剂芯，薄膜包衣导致表面粗糙度增加；对于非常多孔的芯，发现粗糙度降低。用低分子量级别的聚合物包衣可生产出表面粗糙的片剂；增加聚合物分子量会使表面更光滑，在中等分子量级别时粗糙度最小。聚合物浓度增加到2% w/v以上以及薄膜厚度增加到140微米时，粗糙度都会增加。薄膜厚度为20微米时粗糙度最小。低浓度（０-25% v/v）添加颜料会使表面粗糙度略有增加，但在高于临界颜料体积浓度时，表面会非常粗糙。结果表明该方法在产品开发过程中优化薄膜制剂和工艺条件方面的潜力。
