Polymer Composite Solid Dispersions for pH-Independent API Release
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Solution Overview
Problem
Poorly water-soluble APIs exhibit variable absorption and bioavailability due to pH-dependent solubility profiles in the gastrointestinal tract, leading to inconsistent therapeutic effects and drug release, which existing solid dispersion formulations using single polymers fail to address effectively.
Innovation Solution
Combining water-soluble and pH-sensitive polymers, along with pharmaceutically acceptable surfactants, to form a matrix that enhances solubility and stabilizes API dissolution across varying pH levels in the GI tract, ensuring consistent absorption and reduced food effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a water-soluble polymer is used for solid dispersion, then API solubility in aqueous medium is improved, but supersaturation of API occurs causing recrystallization that reduces bioavailability
Solution Approach 1:
The patent combines water-soluble polymers with pH-sensitive polymers to create a composite solid dispersion system. The water-soluble polymer component provides initial solubility enhancement, while the pH-sensitive polymer component controls dissolution to prevent supersaturation and recrystallization, thereby maintaining reliable bioavailability across different GI pH conditions.
Solution Approach 2:
The patent utilizes pH-sensitive polymers that change their solubility parameters in response to pH changes along the GI tract. This parameter change allows the formulation to maintain API solubility at low pH while preventing supersaturation at higher pH, thus resolving the contradiction between solubility improvement and bioavailability maintenance.
2Quantity of substance
If an enteric polymer is used for solid dispersion, then solubility of weakly basic APIs at higher pH is improved, but API dissolution in gastric fluid is delayed causing difficulty to maintain therapeutic concentration
Solution Approach 1:
The patent creates a composite system combining enteric (pH-sensitive) polymers with water-soluble polymers. The enteric polymer provides pH-dependent solubility enhancement for weakly basic APIs at higher pH, while the water-soluble polymer ensures adequate dissolution in gastric fluid, together maintaining reliable therapeutic concentrations throughout the GI tract.
Solution Approach 2:
The formulation exploits pH parameter changes to achieve differential dissolution behavior. The pH-sensitive polymer remains relatively insoluble at gastric pH to allow controlled release, while becoming soluble at intestinal pH to enhance API solubility, thus resolving the contradiction between maintaining therapeutic concentration and improving solubility at higher pH.
3Quantity of substance
If a gastric-soluble polymer is used for solid dispersion, then solubility of weakly acidic APIs at lower pH is improved, but precipitation of polymer in intestine fluid causes variable drug absorption and bioavailability
Solution Approach 1:
The patent combines gastric-soluble polymers with pH-sensitive polymers in a composite formulation. The gastric-soluble polymer enhances API solubility at lower gastric pH, while the pH-sensitive polymer prevents precipitation in intestinal fluid by maintaining solubility at higher pH, thus ensuring consistent and reliable drug absorption across the GI tract.
Solution Approach 2:
The formulation utilizes pH parameter changes to control polymer solubility dynamically. The gastric-soluble polymer provides solubility enhancement at low pH where it is needed, while the pH-sensitive polymer undergoes parameter change at higher intestinal pH to prevent precipitation, resolving the contradiction between improving low-pH solubility and maintaining absorption consistency.
4Device complexity
If only one polymer is used for solid dispersion, then formulation complexity is reduced, but variable API dissolution in GI fluid causes variable pharmacokinetics profiles
Solution Approach 1:
The patent employs composite materials comprising both water-soluble polymers and pH-sensitive polymers in specific combinations. This composite approach provides complementary functions that ensure consistent API dissolution across varying GI pH conditions, achieving reliable pharmacokinetics profiles while managing formulation complexity through systematic polymer selection and ratio optimization.
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 formulation provides reproducible and continuous drug release throughout the GI tract, ensuring consistent API absorption and stable PK profiles with minimized pH sensitivity, thereby improving bioavailability.
Implementation Method 1
Solid dispersion of a poorly water soluble API can be prepared by dispersing the API in a polymer matrix of either a water-soluble or a pH sensitive polymer in nature to improve the aqueous solubility
Implementation Method 2
pH sensitive polymer in nature to improve the aqueous solubility... For solid dispersion of API with an enteric polymer, very low level of API dissolution in gastric fluid of low pH range
Data Source
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AI summary
This present invention is concerned with novel solid dispersion pharmaceutical compositions for preparation of composition which is comprised of a compound with poor water solubility (a weakly basic, neutral and/or non-ionizable, or a weakly acidic compound), water-soluble polymer(s), pH-sensitive polymer(s) (either enteric polymer or gastric- soluble polymer that is soluble at gastric fluid and insoluble at intestine pH range such as Eudragit E), and/or pharmaceutical acceptable surfactant(s) that would improve the solubility/dissolution of the compound in aqueous media of both low and neutral pHs and provide a relative pH-independent dissolution profile.