Aqueous Lipid Formulation pH Adjustment for Hydrolysis Control
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Solution Overview
Problem
Existing aqueous lipid and liposome formulations face challenges in chemical stability due to ester hydrolysis, particularly under acidic or basic conditions, which limits their shelf-life for pharmaceutical applications.
Innovation Solution
An aqueous formulation comprising lipids with ester, thioester, or amide bonds and a pH adjusting agent, with a pH range of 2 to 5.5, is developed to enhance chemical stability and extend shelf-life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liposomes are stored in aqueous phase at neutral pH (6-7), then the formulation maintains physiological compatibility, but ester hydrolysis accelerates and chemical stability decreases
Solution Approach 1:
The patent applies parameter changes by adjusting the pH of the aqueous formulation from the conventional neutral range (6-7) to an acidic range (2-5.5). This parameter modification fundamentally alters the hydrolysis kinetics of ester bonds in lipids, reducing the hydrolysis rate by factors of 10-100 compared to neutral pH conditions. The pH adjusting agents (acids or buffers) are incorporated into the liposome formulation to maintain this stable acidic environment throughout storage, thereby preserving chemical stability while extending shelf-life.
2Reliability
If freezing and/or lyophilization is used to prevent hydrolysis, then chemical stability improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the need for complex freezing and lyophilization processes by introducing a simpler alternative: pH adjustment. By removing the requirement for these additional technical steps and cryoprotectants, the formulation achieves comparable or superior chemical stability through a single parameter modification (pH adjustment), thereby simplifying the manufacturing process and reducing costs while maintaining reliability.
Solution Approach 2:
Instead of changing the physical state of the formulation through freezing or lyophilization, the patent changes the chemical parameter (pH) to achieve stability. This alternative approach avoids the complexity of phase transition processes while achieving the same goal of preventing hydrolysis, thus resolving the contradiction between stability and manufacturing simplicity.
3Duration of action of stationary object
If cryoprotectants are added to enable freezing, then shelf-life stability improves, but product properties may be affected in undesired ways
Solution Approach 1:
The patent removes the need for cryoprotectants entirely by achieving stability through pH adjustment alone. This extraction of unnecessary additives eliminates potential harmful effects on product properties such as altered phase behavior, reduced encapsulation efficiency, or interference with drug release kinetics, while still achieving extended shelf-life stability.
Solution Approach 2:
By changing the pH parameter instead of adding cryoprotectants, the patent achieves shelf-life extension without introducing substances that could adversely affect product properties. The pH adjustment method provides a cleaner solution that maintains the intrinsic characteristics of the liposome formulation while achieving the desired stability.
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 significantly reduces the hydrolysis rate of lipids, thereby increasing the chemical stability and shelf-life of aqueous lipid and liposome formulations, particularly for pharmaceutical applications.
Implementation Method 1
These ester bonds are prone to chemical hydrolysis, which is accelerated under acidic or basic conditions (acidic or basic ester hydrolysis). If the liposomes or other systems that are present as lyotropic lipid phases are to be stored several months or years in the aqueous phase, ester hydrolysis may become a limiting factor for shelf-life stability.
Data Source
AI summary
The present invention relates to aqueous lipid and/or liposome formulations with an increased chemical stability, to methods of preparing such aqueous formulations as well as to kits comprising them. The present invention further relates to methods of preparing lipid-based pharmaceutical compositions, to pharmaceutical compositions prepared by such methods and to methods of chemically stabilizing aqueous lipid and/or liposome formulations.