Enteric Capsule Coating for High-Speed Filling Durability
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Solution Overview
Problem
Existing processes for preparing enteric-coated hard-shell capsules face challenges in maintaining mechanical resistance during high-speed processing in automated capsule-filling machines, particularly when coated in a pre-locked state, leading to issues like premature release in acidic conditions and reduced dissolution at higher pH.
Innovation Solution
A process for preparing polymer-coated hard-shell capsules using a coating layer comprising anionic cellulose and starches with high amylose content, applied in the pre-locked state, which provides a flexible coating that withstands mechanical stress, ensuring less than 10% active ingredient release at pH 1.2 and rapid dissolution at pH 5.5 or above.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hard-shell capsules are coated with enteric coating in a pre-locked state before filling, then the coating can provide enteric protection, but the mechanical resistance of the capsule is reduced during high-speed processing in automated filling machines
Solution Approach 1:
The patent modifies the coating composition parameters by incorporating specific plasticizers and adhesion promoters in controlled amounts, changing the physical and chemical properties of the coating to achieve both flexibility and strength. This resolves the contradiction by adjusting coating parameters to maintain mechanical resistance while providing enteric protection during high-speed processing.
Solution Approach 2:
The patent uses composite coating materials comprising multiple components including polymers, plasticizers, and adhesion promoters in specific ratios. This composite approach allows the coating to simultaneously provide enteric protection and maintain mechanical resistance during automated filling operations by combining the beneficial properties of different materials.
2Productivity
If the coating layer is applied in the pre-locked state, then the capsule can be processed in automated machines, but the coating may crack or break under mechanical stress
Solution Approach 1:
The patent employs a flexible coating film design with controlled thickness and composition that can accommodate mechanical stresses during high-speed processing. The coating is formulated to be flexible enough to prevent cracking while maintaining integrity, enabling reliable automated machine processing without compromising coating reliability.
3Reliability
If the coating is applied thickly to ensure enteric protection, then dissolution at higher pH is improved, but the mechanical resistance and flexibility are reduced
Solution Approach 1:
The patent optimizes coating thickness parameters and compositional parameters to achieve the desired balance. By controlling the amount of polymer, plasticizer, and adhesion promoter, the coating provides sufficient enteric protection and dissolution properties while maintaining mechanical resistance and flexibility for automated processing.
Solution Approach 2:
The composite coating formulation includes multiple components in specific ratios that work synergistically. The polymer provides enteric protection, while plasticizers and adhesion promoters maintain mechanical properties. This composite approach enables the coating to be sufficiently thick for reliable dissolution without becoming brittle or losing mechanical resistance.
Data Source
Figure 1
AI summary
The invention is concerned with a process for preparing a polymer coated hard-shell capsule, filled with a fill comprising a biologically active ingredient, wherein the hard-shell capsule is comprising a body and a cap, wherein in a closed state the cap overlaps the body either in a pre-locked state or in a final-locked state, wherein the material of the body and the cap comprises an ethyl-, methyl- or propyl-ether of cellulose, starch or pullulan, wherein the hard-shell capsule is coated with a coating layer that covers the hard-shell capsule in the pre-locked state, wherein the coating layer is comprising one or more anionic cellulose(s), ethyl cellulose and/or one or more starches comprising at least 35 % by weight amylose, wherein the coating layer is present in an amount of about 1 to 5.8 mg/cm2, wherein a dried film with a thickness of 250 µm, corresponding to the composition of the coating layer, shows an elongation at break of about 15 to 500 %, wherein the polymer-coated hard-shell capsule is provided in the pre-locked state to a capsule-filling machine, which performs the steps of separating the body and the cap, filling the body with the fill and rejoining the body and the cap in the final-locked state.