Hydroxyalkyl Methylcellulose Viscosity Stability in Liquid Diluents
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Solution Overview
Problem
Liquid compositions comprising an organic liquid diluent and cellulose ethers, such as hydroxypropyl methylcellulose, often exhibit unstable viscosity upon storage, leading to increased costs and limitations in active ingredient concentration due to viscosity issues, which complicates storage and processing.
Innovation Solution
Incorporating hydroxyalkyl methylcellulose with a specific ratio of substituted and unsubstituted hydroxyalkoxyl groups, where the ratio of substituted to unsubstituted hydroxyalkoxyl groups is at least 0.30, improves viscosity stability by reducing the rate of viscosity increase during storage, allowing for higher concentrations of cellulose ether without compromising flowability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid compositions comprise cellulose ether (hydroxypropyl methylcellulose) and organic liquid diluent, then active ingredients can be incorporated and spray-dried to produce solid dispersions, but the viscosity increases hugely after storage over extended time period
Solution Approach 1:
The invention changes the chemical structure parameters of the cellulose ether by specifying a hydroxyalkyl methylcellulose with a particular ratio of substituted to unsubstituted hydroxyalkoxyl groups (at least 0.30). This parameter change in the polymer structure fundamentally alters the viscosity stability behavior, allowing the liquid composition to maintain stable viscosity upon storage while still enabling high active ingredient incorporation and subsequent spray-drying to produce solid dispersions.
2Reliability
If storage temperature is reduced below room temperature to avoid viscosity increase, then viscosity stability improves, but storage costs increase and storage becomes more complicated
Solution Approach 1:
The invention changes the chemical composition parameters of the liquid composition by selecting a specific hydroxyalkyl methylcellulose with a defined ratio of substituted to unsubstituted hydroxyalkoxyl groups (at least 0.30). This parameter change enables the composition to maintain viscosity stability at room temperature, eliminating the need for refrigerated storage and thereby reducing storage complexity and costs.
3Quantity of substance
If higher concentration of cellulose ether is used in liquid composition, then more active ingredient can be incorporated, but viscosity increases limiting the achievable content
Solution Approach 1:
The invention changes the molecular structure parameters of the cellulose ether by specifying a hydroxyalkyl methylcellulose with a particular ratio of substituted to unsubstituted hydroxyalkoxyl groups (at least 0.30). This structural parameter change allows higher concentrations of cellulose ether to be incorporated into the liquid composition without causing excessive viscosity increase, thereby enabling higher active ingredient loading while maintaining processability.
Data Source
AI summary
A liquid composition which comprises an organic liquid diluent and a hydroxyalkyl methylcellulose which has a certain distribution of substituted hydroxyalkoxyl groups and unsubstituted hydroxyalkoxyl groups is stable over an extended time period. In the hydroxyalkyl methylcellulose hydroxyalkoxyl groups are classified into a fraction (A) and a fraction (B), wherein fraction (A) represents the sum of all molar fractions of substituted hydroxyalkoxyl groups having hydroxyl groups substituted further with methoxyl groups and fraction (B) represents the sum of all molar fractions of unsubstituted hydroxyalkoxyl groups having hydroxyl groups not substituted further with methoxyl groups and wherein the ratio fraction (A)/fraction (B) is at least 0.30. The liquid composition is useful for preparing a solid dispersion comprising at least one active ingredient in at least one hydroxypropyl methylcellulose by spray-drying.