Preliminary assessment of an image analysis method for the evaluation of pharmaceutical coatings

This article describes the development and preliminary assessment of an innovative image analysis method for the evaluation of pharmaceutical coatings. Nonpareils previously hot-melt coated with a red water-soluble dye incorporated into polyethylene glycol were employed to develop and evaluate the new method. Digital images of batch samples were acquired and transferred to a PC for evaluation by image analysis software. Standard deviations generated for the optical densities of individual nonpareils in each batch sample were utilized to evaluate coating uniformity. Mean optical densities generated for each batch sample were used to evaluate the mean coating thickness. Method precision determinations, using an average sample size of 221 nonpareils, returned a relative standard deviation of 2.47% for coating uniformity and 1.71% for coating thickness. The new method is rapid, objective, and relatively inexpensive. It proved to be both qualitative and quantitative for coating uniformity, qualitative for coating thickness, and maintained a high degree of precision. The method can be used independently or in conjunction with other methods to eliminate their subjective aspects regarding sample selection.