Context: Although several methods have been investigated to measure the film thickness of tablets and its correlation with the dissolution behavior, much fewer such investigations exist for pharmaceutical pellets.
Objective: To study the possibility of measuring the film thickness and predicting the dissolution behavior of pellets produced in different fluid bed equipments with Raman spectroscopy.
Materials and methods: Pyridoxine hydrochloride-layered pellets were produced and coated in two different Strea-1 equipments. Raman spectra were collected and analysed to set up a calibration model based on the film thickness data calculated from Camsizer analysis results. Dissolution tests were done according to Ph. Eur. standards.
Results: Raman spectroscopy proved to be a good tool in the measurement of film thickness. Polymer weight gain showed a linear correlation with film thickness but was a poor predictor of dissolution results below a threshold value.
Conclusion: The Raman spectroscopic measurement of a small sample can provide accurate data of the film thickness. The investigation suggests that a threshold value might exist for the film thickness above which it can be used to judge future dissolution results.
Keywords: Chemometric analysis; PCA; PLS; Raman; dissolution; film thickness; pellet.