How to determine a coating level Evaluating different methods to gain reliable data

摘要

In pharmaceutical film-coating applications, various approaches are known to evaluate the coating level (1-3). Yet huge differences in accuracy and reliability can be seen when comparing methods such as weight, colour and photometrical measuring. The determination of a tracer added to the coating formulation (photometrical measuring) was found to be the best method. A huge advantage is seen in the fact that the amount of coating material applied onto an individual tablet can be determined. This allows a precise correlation of a tablet's dissolution profile and the individually borne coat. Gravimetric measuring showed a standard deviation too high for reliable testing and colour measuring couldn't indicate the coating level at all. In the present case study of a solid oral dosage form, the taste masking functionality and the dissolution profile in phosphate buffer respectivelycould clearly be correlated with the coating level determined photometrically. If could be shown that 3.5 mg/cm~2 of applied coating formulation already offer maximum functionality.