Liposomal Composition for Ambient-Temperature Weak Acid Encapsulation
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Solution Overview
Problem
Existing methods for encapsulating weak acid drugs like prostaglandins in liposomes suffer from low encapsulation efficiency at ambient temperatures, require heating which accelerates drug degradation, and result in unstable compositions for long-term storage, leading to potential overdose and stability issues.
Innovation Solution
A liposomal composition is developed using a lipid mixture with a hydrophilic polymer conjugated lipid at less than 3% molar percentage, encapsulating a weak acid salt and a mild acidic agent, allowing encapsulation at ambient temperature and providing sustained release, enhanced stability, and reduced side effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heating above transitional temperature is used to increase liposome permeability for loading prostaglandins, then encapsulation efficiency is improved, but drug degradation accelerates and stability deteriorates
Solution Approach 1:
The patent changes the temperature parameter from elevated (>60°C) to ambient temperature for the loading process. This parameter change allows encapsulation to proceed without thermal degradation of the prostaglandin drug, resolving the contradiction between achieving sufficient encapsulation efficiency and maintaining drug stability.
Solution Approach 2:
The patent introduces a weak acid salt as an intermediary substance that facilitates prostaglandin loading into liposomes at ambient temperature. The weak acid salt creates a pH gradient that drives prostaglandin encapsulation without requiring elevated temperatures, thus maintaining drug stability while achieving encapsulation efficiency.
2Ease of manufacture
If conventional liposomal dispersion is used with passive loading, then preparation simplicity is improved, but encapsulation efficiency deteriorates leading to overdose problems
Solution Approach 1:
The weak acid salt acts as a mediator that enables efficient prostaglandin encapsulation without complex procedures. By utilizing the pH gradient created by the weak acid salt, the system achieves high encapsulation efficiency while maintaining the simplicity of ambient temperature preparation, avoiding both overdose and complex manufacturing.
3Stability of the object's composition
If high concentration of hydrophilic polymer conjugated lipid is used in liposome membrane, then liposome stability is improved, but encapsulation efficiency of weak acid drugs deteriorates
Solution Approach 1:
The weak acid salt serves as an intermediary that enables efficient drug loading even in the presence of hydrophilic polymer conjugated lipids. The pH gradient mechanism driven by the weak acid salt overcomes the reduced permeability caused by high polymer lipid concentrations, achieving both liposome stability and high encapsulation efficiency.
Solution Approach 2:
The patent utilizes pH as a controlling parameter, creating a pH gradient through the weak acid salt. This parameter change enables the driving force for encapsulation to overcome the barrier presented by high concentrations of hydrophilic polymer conjugated lipids, simultaneously achieving stability and efficiency.
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 method achieves high encapsulation efficiency (>85%) of prostaglandins in liposomes, ensuring stable storage for at least one year and reducing side effects by controlled release, suitable for clinical use.
Implementation Method 1
U.S. Patent no. U.S. Pat. No. 5,939,096 utilizes a proton shuttle mechanism involving the salt of a chemical entity to generate a higher inside/lower outside pH gradient
Implementation Method 2
the interior space is separated from the aqueous medium by a membrane comprised of a lipid mixture
Implementation Method 3
the surface of liposome is coated with poly (ethylene glycol) (PEG). PEG-derivatized liposomes, known as stealth liposomes
Data Source
AI summary
Provided is a method for preparing a liposomal composition. The method comprises the step of contacting a liposome solution with a mild acidic agent for a limited time. The liposome solution comprises a weak acid salt encapsulated within an aqueous interior space separated from the aqueous medium by a membrane comprised of a lipid mixture containing one or more lipids and a hydrophilic polymer conjugated lipid at a molar percentage of less than 3% based on the total amount of the lipid mixture. The time for encapsulating the agent to a desired amount at a predetermined ratio to lipids is dramatically reduced even under a condition without elevating the temperature to above ambient environment.