Non-destructive determination of the coating film thickness by X-ray powder diffractometry and correlation with the dissolution behavior of film-coated tablets.

The goal of this project was to determine the effect of the thickness of the coating film on the dissolution behavior of tablets. Commercially available film-coated tablets containing aspirin, acetaminophen and caffeine, were used as the model system. First, a non-destructive X-ray microdiffractometric technique was developed to quantify the thickness of the film-coating in intact tablets. The same tablets were then subjected to dissolution tests. There was an inverse correlation between the cumulative amount of drug in solution at 5min and the thickness of the coating film. As the coating thickness increased, the initiation of tablet dissolution was delayed, resulting in a decrease in the cumulative amount of drug in solution. Finally, the technique was applied to formulations marketed by different companies. The X-ray microdiffractometric technique has the potential to predict the dissolution behavior of tablets.