Weak Acid Liposome Loading via pH Gradient Without Bicarbonate Instability

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Solution Overview

Problem

Current methods for loading weak acid drugs into liposomes suffer from poor drug loading efficiency and unsatisfactory controlled release, with bicarbonate salts causing destabilization and premature drug release.

Innovation Solution

A pharmaceutical composition comprising liposomes with a bicarbonate salt in the internal aqueous medium and a weak acid drug, maintained in an external medium with a specific molar ratio and pH gradient to enhance drug encapsulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If bicarbonate salt is used for drug loading, then drug encapsulation efficiency is improved, but liposome stability deteriorates due to gas accumulation and premature drug release

Engineering Contradiction:

Improvedrug encapsulation efficiencyVSAvoidliposome stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent uses formic acid as an intermediary substance to establish the pH gradient for drug loading instead of bicarbonate salt. Formic acid serves as a mediator that creates the necessary internal/external pH difference without causing gas accumulation, thereby resolving the contradiction between drug encapsulation efficiency and liposome stability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical parameter (pH gradient establishment method) from using bicarbonate salt to using formic acid. This parameter change allows achieving high drug encapsulation efficiency while avoiding the destabilizing effects of bicarbonate, thus resolving the contradiction between quantity of drug loaded and stability of liposome structure

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If higher pH gradient is established for weak acid drug loading, then drug encapsulation efficiency is improved, but controlled release performance deteriorates

Engineering Contradiction:

Improvedrug loading efficiencyVSAvoidcontrolled release rate

Core Design Contradiction:

Quantity of substanceVSDuration of action of moving object

Solution Approach 1:

The patent optimizes the pH gradient parameters by using formic acid at controlled concentrations (50-1000 mM) to establish a moderate pH difference between internal and external media. This parameter optimization achieves high drug loading efficiency while maintaining controlled release characteristics, resolving the contradiction between drug loading quantity and release duration

Inventive Principle:

Principle #35Parameter changes

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 high drug encapsulation efficiency and controlled release, effectively delivering therapeutic agents to treat respiratory diseases.

Implementation Method 1

the pH gradient is established by a salt of a weak acid

Methodology Applied

Scientific EffectpH gradient:

Implementation Method 2

A method for establishing a lower outside/higher inside pH gradient in liposomes is provided

Methodology Applied

Scientific EffectProton gradient:

Data Source

PatentUS12551437B2Liposome compositions comprising weak acid drugs and uses thereof

Publication Date: 2026.02.17 PHARMOSA BIOPHARM INC

AI summary

The present invention relates to a pharmaceutical composition comprising a weak acid drug, with the use of a bicarbonate salt to achieve a high incorporation of the drug into the liposome and a better therapeutic efficacy. Also disclosed is a method for treating a respiratory disease using the pharmaceutical composition disclosed herein.