Polymeric Steric Stabilizer for Dispersed Particulate Material
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Solution Overview
Problem
Existing administrable compositions face challenges in maintaining particulate material in a dispersed state, especially in high ionic strength liquid carriers and upon administration, leading to potential flocculation and ineffective dosing.
Innovation Solution
A composition with particulate material less than 0.5 microns, stabilized by a polymeric steric stabilizer comprising a steric stabilizing and anchoring polymeric segment derived from ethylenically unsaturated monomers, polymerized by living techniques, which secures the stabilizer to the particulate material and provides steric repulsion for stability across diverse liquid carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional stabilisers are used in high ionic strength liquid carriers, then the composition can be formulated with isotonic properties, but the stabilisers become ineffective and particulate material flocculates
Solution Approach 1:
The invention changes the chemical parameters of the stabiliser by using polymeric materials with specific functional groups (carboxylic acid, phosphonic acid, phosphate, sulfonic acid, or hydroxyl groups) that can function effectively in high ionic strength environments. The polymer composition and molecular weight are specifically controlled to maintain stability in isotonic carriers where conventional stabilisers fail.
Solution Approach 2:
The invention uses composite polymeric stabilisers that combine multiple functional groups within a single polymer structure. These composite materials provide both the necessary anchoring to particulate material and the steric stabilization required in high ionic strength environments, overcoming the limitations of single-function stabilisers.
2Ease of operation
If the volume of liquid carrier is increased relative to particulate material, then the composition becomes more flowable, but the equilibrium shifts and particulate material flocculates
Solution Approach 1:
The invention changes the stabiliser concentration parameter and uses polymers with specific molecular weights (1,000 to 50,000) and functional group densities that maintain effective stabilisation even when the liquid carrier volume is increased. The polymeric structure provides sufficient steric barrier at lower concentrations to prevent flocculation during dilution.
Solution Approach 2:
The stabiliser is pre-attached to the particulate material surface in sufficient quantity before administration. This preliminary stabilisation ensures that when the composition is diluted in the body (increasing liquid volume), the particulate material remains protected from flocculation because the stabiliser is already in place on the particle surface.
3Quantity of substance
If particulate material concentration is increased above 40 wt.%, then the therapeutic dose is higher, but the particulate material cannot remain in a dispersed and readily flowable state
Solution Approach 1:
The invention uses composite polymeric stabilisers with multiple functional groups that provide enhanced anchoring and steric stabilization. This allows the formulation to maintain dispersed, flowable states at higher particulate material concentrations (above 40 wt.%) that would otherwise cause aggregation and poor flow properties.
Solution Approach 2:
The invention changes the stabiliser-to-particulate material ratio parameter and uses polymers with optimized molecular weights and functional group densities. These parameter changes enable the system to maintain stability and flowability at high particulate concentrations that are therapeutically beneficial but traditionally cause flocculation.
4Reliability
If electrostatic stabilisers are used, then they provide repulsion forces in low ionic strength environments, but they fail in high ionic strength liquid carriers
Solution Approach 1:
The invention changes the stabilisation mechanism from electrostatic to steric by using polymeric materials. This parameter change allows the stabiliser to function effectively across the full range of ionic strengths, including high ionic strength isotonic carriers where electrostatic stabilisers fail because steric repulsion is not screened by ions.
Solution Approach 2:
The polymeric stabiliser acts as an intermediary between the particulate material and the liquid carrier. The polymer chains extend into the carrier medium and provide physical steric barriers that prevent particle aggregation, mediating the interaction in a way that is insensitive to ionic strength variations.
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 composition achieves stable dispersion of particulate material at both high and low concentrations, maintaining stability in vivo and across various liquid environments, enhancing therapeutic and diagnostic applications.
Implementation Method 1
the anchoring polymeric segment has an affinity toward the surface of the particulate material and secures the stabiliser to the particulate material
Implementation Method 2
presenting electrostatic and/or steric repulsion forces that help maintain the particulate material in a dispersed state
Data Source
Figure 1~2
AI summary
The present invention relates to a composition suitable for administration to a subject, the composition comprising pharmacologically acceptable particulate material dispersed throughout a pharmacologically acceptable liquid carrier, the particulate material being maintained in the dispersed state by a steric stabiliser, wherein the steric stabiliser is a polymeric material comprising a steric stabilising polymeric segment and an anchoring polymeric segment, one or both of which are derived from one or more ethylenically unsaturated monomers that have been polymerised by a living polymerisation technique, wherein the steric stabilising polymeric segment is different from the anchoring polymeric segment, and wherein the anchoring polymeric segment has an affinity toward the surface of the particulate material and secures the stabiliser to the particulate material.