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 5 min 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.