Multi-Layer pH-Dependent Coating for Colon Release
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Solution Overview
Problem
Existing formulations for targeted release of active ingredients in the colon are unreliable due to inter-individual variability in intestinal pH, leading to premature, delayed, or failed release, with a narrow working range that does not account for fluctuations in pH values.
Innovation Solution
A multi-layer coating system where each layer is soluble or permeable within specific pH ranges, ensuring that only one layer dissolves at a time, with the innermost layer dissolving upon entry into the cecum and the outer layers protecting against gastric and intestinal environments, allowing for controlled release in the colon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single pH threshold coating is used to trigger release, then the formulation is simple to manufacture, but the working range is very narrow (around 0.5 pH levels) and unreliable due to inter-individual variability in intestinal pH
Solution Approach 1:
The single coating layer is segmented into multiple layers with different pH thresholds. The formulation uses a multi-layer coating system where each layer has a specific solubility threshold (e.g., first layer at pH 6.0, second layer at pH 6.5, third layer at pH 7.0), allowing the system to accommodate inter-individual variability in intestinal pH and ensure reliable release in the large intestine regardless of the maximum pH reached in the small intestine.
2Adaptability or versatility
If the solubility threshold of the anionic polymer is lowered to achieve release in individuals with lower pH values, then the working range is extended, but release may occur too early in individuals with higher pH values
Solution Approach 1:
Instead of using a single polymer with a lowered threshold, the system segments the coating into multiple layers with progressively lower pH thresholds. This ensures that release only occurs when all layers dissolve, which happens when the pH drops sufficiently in the large intestine, preventing both premature and delayed release.
Solution Approach 2:
The conventional approach of using a single high threshold is inverted by applying multiple layers with progressively lower thresholds. The outermost layer has the highest threshold and the innermost layer has the lowest threshold, creating a cumulative effect that ensures release only occurs under the right conditions.
3Reliability
If multiple layers with different pH thresholds are used to extend the working range, then release reliability is improved, but the device complexity increases
Solution Approach 1:
The coating is segmented into multiple functional layers, each with a specific pH threshold. This segmentation allows the system to accommodate a wide range of intestinal pH values while maintaining a relatively simple overall structure that can be applied using conventional coating techniques.
Solution Approach 2:
Each coating layer serves multiple functions: it acts as a barrier to acid in the stomach, provides a progressive pH threshold for controlled dissolution, and contributes to the overall structural integrity of the formulation. This multi-functionality reduces the need for additional components.
4Reliability
If a slowly dissolving layer is applied under the enteric layer to delay release, then premature release in the small intestine is prevented, but the release timing becomes more sensitive to pH variability
Solution Approach 1:
The protective function is segmented into multiple enteric coating layers with different pH thresholds rather than relying on a single slowly dissolving layer. This segmentation provides progressive protection and controlled dissolution, preventing premature release while maintaining consistent timing across different individuals.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This system provides a wider working range and increased tolerance to pH fluctuations, ensuring safe and reliable release of active ingredients in the colon, even in individuals with low or variable pH values in the small intestine.
Implementation Method 1
each layer is soluble or permeable within specific pH ranges, ensuring that only one layer dissolves at a time
Data Source
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AI summary
The present invention relates to a formulation for the controlled release of active ingredients after the passage of the ileo-cecal- valve, comprising one or more active ingredients or one or more active ingredient containing cores (W), enveloped by one or more envelopments (C), which are dissoluble or permeable above an individual defined pH value and are dissoluble or permeable below another individual defined pH value, again enveloped by an envelopment (E), which is dissoluble or permeable above still another individual defined pH value.