Dual-Layer Colon Drug Delivery System
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Solution Overview
Problem
Current oral colon-targeted drug delivery systems face challenges in ensuring complete drug arrival at the colon site due to individual differences in gastrointestinal pH and length, leading to premature drug release in the small intestine and systemic side effects, with pH-dependent systems being unreliable and bacterial flora-sensitive systems prone to premature drug release due to water absorption.
Innovation Solution
A dual-layer oral colon-targeted delivery system combining a pH-sensitive layer with a bacterial flora-sensitive layer, using β-cyclodextrin derivatives and plant extracts, and methacrylic acid-methyl methacrylate copolymer, to protect drugs until they reach the colon, ensuring selective release and reducing side effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pH-dependent or time-dependent delivery system is used, then the system structure is simple, but the drug release location cannot be precisely controlled due to individual differences in gastrointestinal pH and length, leading to premature release in the small intestine
Solution Approach 1:
The delivery system is divided into multiple functional layers: an outer pH-sensitive polymer layer (Eudragit S100) that dissolves at pH≥7, a middle bacterial flora-sensitive layer (crosslinked β-cyclodextrin polymer) that degrades via bacterial enzymes, and an inner drug core. This segmentation allows each layer to perform its specific function sequentially, ensuring the drug reaches the colon before release.
Solution Approach 2:
The invention uses composite materials combining pH-sensitive polymers (Eudragit S100) and bacterial flora-sensitive materials (crosslinked β-cyclodextrin polymer). This composite structure leverages the advantages of both materials: the pH-sensitive layer provides initial protection through the small intestine, while the crosslinked bacterial-sensitive layer ensures final colon-specific release, overcoming the limitations of single-material systems.
2Reliability
If azo-containing compounds are used for bacterial flora sensitivity, then colon targeting is enhanced, but the compounds are strong carcinogens
Solution Approach 1:
The invention replaces permanent carcinogenic azo compounds with a biodegradable crosslinked β-cyclodextrin polymer structure. This polymer is designed to be stable during transit through the gastrointestinal tract but degrades completely upon encountering bacterial flora in the colon, releasing the drug without leaving harmful residues. The temporary nature of the carrier structure eliminates long-term carcinogenic risks.
3Object-affected harmful factors
If polysaccharides are used as bacterial flora-sensitive materials, then the system is safe and biodegradable, but the materials are extremely easy to absorb water and swell causing premature drug release
Solution Approach 1:
The β-cyclodextrin polymer is crosslinked to create a network structure with controlled porosity and water absorption characteristics. The crosslinking density and network architecture are specifically designed to allow gradual water penetration and enzymatic degradation only under colonic conditions, preventing premature swelling and drug release in the stomach and small intestine while maintaining safety and biodegradability.
4Reliability
If a dual-layer system combining pH-sensitive and bacterial flora-sensitive mechanisms is used, then selective dissolution and release at the colon site is enhanced, but the device complexity increases
Solution Approach 1:
The delivery system employs a nested multi-layer structure where the pH-sensitive polymer layer (Eudragit S100) forms the outer protective shell, the crosslinked β-cyclodextrin polymer forms the middle layer, and the drug core is nested at the center. Each layer is sequentially degraded or dissolved as the system progresses through the gastrointestinal tract, with the outer layer dissolving first at pH≥7, followed by the middle layer degrading via bacterial enzymes in the colon, ensuring controlled drug release without requiring complex external control mechanisms.
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
The system effectively enhances drug delivery to the colon site, reducing the frequency of administration and systemic side effects, while maintaining therapeutic efficacy through targeted nanoparticle delivery and slow release of drugs at the inflammatory site.
Implementation Method 1
a pH sensitive layer which contains any polymer composition dissolved under the condition of pH≥7
Implementation Method 2
These bacterial floras can secrete many specific reductases and hydrolases, such as β-glucuronidase, β-glucosidase, cellulase, nitroreductase, azo reductase, α-decarboxylase, cholesterol dehydrogenase and the like, while azo polymers, polysaccharides and other materials can be degraded by colon-specific enzymes
Implementation Method 3
The polysaccharides comprise β-cyclodextrin derivative and/or plant extracts and derivatives thereof
Data Source
AI summary
An oral colon-targeted delivery system is described, which includes a bacterial flora sensitive layer which contains polysaccharides and covers the exterior of active ingredients, a pH sensitive layer which contains any polymer composition dissolved under the condition of pH≥7 and covers the exterior of the bacterial flora sensitive layer. A preparation method and applications of the delivery system are also described. According to the oral colon-targeted delivery system combined with the pH sensitive and bacterial flora sensitive mechanisms, the selective dissolution and release of active ingredients in the colon site are effectively improved by using double-layer protection so that the therapeutic or diagnostic effect is enhanced, and the application prospect is broad.