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Formulation and Delivery - Chemical

(M1230-07-39) A Comparative Approach in the Evaluation and Optimization of Enteric Coating for Tablet Formulation

Monday, October 21, 2024
12:30 PM – 1:30 PM MT
Purpose: The principal objective of this study was to perform a comparative analysis between Eudragit® and Acryl-EZE® as polymers used in the formulation of enteric coating for delayed-release tablets. By observing the release profile, this study effectively evaluates an optimal polymer, given the conditions and constraints of the Research and Development (R&D) facility.

Methods: Three separate studies were performed for this enteric coating analysis of this delayed-release tablet formulation. The first study introduced the application of Eudragit® as the primary polymer in the enteric coating formulation and compared the performance of both active and placebo batches. The second study modified the formulation of Eudragit® by increasing the amount of plasticizer on only a placebo batch. The last study evaluated the performance of Acryl-EZE® on both active and placebo batches. Active and placebo batches were manufactured as part of this study. Formulating the active batch required dispensing, screening, and blending all intra-granular materials, producing the pre-blend. Next, the pre-blend was roller compacted into ribbons and milled into granules. The granules were combined with extra-granular ingredients, and a final blend was produced. Comparatively, the placebo batch involved only dispensing, screening, and blending to produce a final blend. Furthermore, both active and placebo batches underwent compression using an oval-shaped tooling. Both the batches were coated to 2% seal coating using PVA-based Opadry® II polymer1. Opadry® II was dissolved in purified water and coating dispersion was prepared. Core tablets were coated to 2% weight gain. In-process samples were weight checked periodically. Ultimately, the seal-coated tablets were adequately stored until needed to perform enteric coating. Eudragit®, Eudragit® (5% more plasticizer), and Acryl-EZE® are powdered polymers that were dissolved in purified water for a minimum of 45 minutes before use. A 12% coating level was standardized among the three enteric coating polymers, ensuring a uniform, thin finish on the tablets. After coating, all batches remained uncured and were stored according to formulation requirements. The coated tablets from each batch were subjected to biphasic dissolution testing. First, a sample of six tablets was placed in an acidic media for 120 minutes. Immediately after, the same tablets were immersed in buffer media for 90 minutes. Acid resistance testing was performed on these tablets using a disintegration tester. The data collected reports a pass/fail condition depending on visible tablet swelling or rupturing (fail) and produces a dissolution profile for active batches.

Results: Two studies were conducted evaluating the performance of Eudragit® as an enteric coating polymer: an active batch and a placebo batch. Results for both batches indicated batch failure due to visible swelling and breaching in the acidic solution (Figure 1). A dissolution profile of the active batch was obtained for further analysis (Figure 2). An additional placebo study was conducted utilizing Eudragit® with 5% additional plasticizer. Once again, the data indicated batch failure due to swelling (Figure 1). The repeated breaching led to future implication of Acryl-EZE® as an ideal polymer. The next two batches utilized Acryl-EZE® for enteric coating on both the placebo and active tablets. After testing, results indicated a passing condition due to no swelling or breaching within the acid media (Figure 1). Dissolution testing for the active batch provided an optimal drug release profile (Figure 2). The dissolution profiles indicated that Acryl-EZE® provides better resistance to gastric conditions than Eudragit® for this formulation, ultimately maintaining coating integrity for delayed release. Analyzing both polymers, Acryl-EZE® has two additional excipients when compared to Eudragit®: anhydrous silica and sodium bicarbonate. Anhydrous silica acts as an anti-caking agent which helps maintain the polymer suspension, increasing stability and preventing agglomeration. Additionally, anhydrous silica has a large surface area and is hygroscopic2. Sodium bicarbonate acts as an alkalizing agent which helps maintain a stable drug microenvironment3. In development, Acryl-EZE® is a co-processed powder prepared by spray drying the polymer with excipients4. The anhydrous silica absorbs excess moisture content, providing a dried coating without requiring additional curing time2. In comparison, Eudragit® is a dry powder, commonly requiring additional processing such as curing under certain conditions4.

Conclusion: In conclusion, this study demonstrated Acryl-EZE® to be the ideal polymer for this enteric coated tablet formulation as compared to Eudragit®. Both active and placebo batches show high resistance to acidic media and the dissolution profile of the active batch showed desired release patterns. Utilizing Acryl-EZE® to externally coat tablets can lead to better manufacturability, better API release, and better product stability.

References: 1. Kerva, A. (2008). Maximizing the gloss of PVA-based film Coating Systems-Colorcon
2. Editorial, P. (2023). Anhydrous colloidal silica excipient: Uses, suppliers, and specifications.
3. Bigoniya, P., Shukla, A., Singh, C. S., & Gotiya, P. (2011). Comparative anti-ulcerogenic study of pantoprazole formulation with and without sodium bicarbonate buffer on pyloric ligated rat. Journal of Pharmacology and Pharmacotherapeutics, 2(3), 179–184. doi:10.4103/0976-500x.83283
4. Technical Information EUDRAGIT® L 30 D-55. (2011, December).

Figure 1. Disintegration testing for all batches

Figure 2. Dissolution profile comparison