A High Performance Liquid Chromatographic Method for the Determination of the Amount of Hydroxypropyl Methylcellulose Applied to Tablets During an Aqueous Film Coating Operation

Abstract

A method for determination of the amount of polymer film coat actually applied to tablets as a result of aqueous film coating was developed using gel permeation chromatography (GPC). A styrene-based GPC column (Ultrastyrage]^R 100A) was found to provide good separation of a commercially available polymer film coat (Opadry^R) from other tablet constituents. The assay method is simple, rapid and reproducible with coefficients of variation less than 2.6% in all cases. The assay is sensitive enough to discriminate between tablets containing different levels of microcrystalline cellulose (MCC) when coated simultaneously. The assay was conducted on polymer extracted from the tablets with a solution of 50/50 methanol/methylene chloride. The addition of MCC to tablet formulations was found to increase the amount of film applied, in a competitive coating operation, when all other factors were held constant.