Evaluating the suitability of a pH-dependent pore former in a sustained release film-coating formulation

Since the development of polymers for enteric coating in the late 1950’s, numerous investigations have illustrated the application of these functional excipients such as poly(methacrylic acid-co-ethyl acrylate). Also mixtures with other polymers like poly(vinyl acetate) have already been well described.

The combination of an insoluble and an enteric polymer allows the alteration of the drug release rate of a coated dosage form during its passage through the gastro intestinal tract of the human body. This allows for instance to achieve a constant release pattern for weak basic drugs. While solubility of basic drugs is high in acid media (gastric passage), the permeation through the coat is restricted by the enteric pore former. As soon as pH-value increases (dosage form enters the intestines), the permeation rate increases due to the solubility of the enteric polymer in this milieu. Hence, the decreasing solubility of the drug is balanced.

The aim of the present investigations was the evaluation of poly(methacrylic acid-co-ethyl acrylate) as pH-dependent pore former in a poly(vinyl acetate) based coat. Of particular challenge was the incompatibility of the two polymer dispersions, disabling a direct formulation of the two components as polymer mixture. In order to gain a homogeneous coat consisting of both polymers in the required ratio, the two dispersions were applied simultaneously in a fluid bed coating process by combining bottom and top spray technology.

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Thorsten Cech 1, Michael G. Herting 2, Susann Just 1, Karsten Mäder 3
1European Application Lab, Pharma Solutions Sales Europe, BASF SE, Germany
2QM Systems, NCM & Processes, BASF SE, Germany
3Faculty of Pharmacy, Martin-Luther-University Halle, Germany
Corresponding author: [email protected]

This is the first poster in a series of several more BASF posters on enteric coating we will publish in the next weeks until our webinar about the newest version of BASF ZoomLab™ with the new enteric coating module on the 24th of September. We also did an interview with one of the “masterminds behind ZoomLab™”. We will publish this interview on the first of September.