Lenalidomide Salt Formulation Stability via Proton Transfer Control
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Solution Overview
Problem
Existing pharmaceutical compositions of lenalidomide acid addition salts lack satisfactory stability and solubility, leading to potential bioavailability issues and challenges in commercial-scale production.
Innovation Solution
A pharmaceutical formulation comprising lenalidomide in the form of a pharmaceutically acceptable acid addition salt, specifically using an acid with a pKa of 4 or less, and excipients that are not capable of accepting protons, to enhance chemical and physical stability and dissolution profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If lenalidomide is formulated with conventional excipients (magnesium stearate, croscarmellose sodium, lactose), then the formulation is manufacturable and processable, but the chemical and physical storage stability deteriorates due to proton acceptance by basic excipients
Solution Approach 1:
The patent removes basic excipients (magnesium stearate, croscarmellose sodium, lactose) that accept protons from the formulation. This extraction of harmful components eliminates the stability-deteriorating interaction while maintaining manufacturability through alternative excipient selection that does not interfere with the acid addition salt stability.
Solution Approach 2:
The patent changes the pH parameter of the formulation by selecting excipients with pKa values that maintain an acidic environment (pH < pKa of lenalidomide salt). This parameter change prevents proton transfer reactions and stabilizes the acid addition salt form during storage and processing.
2Quantity of substance
If strong acids with pKa < -2 are used to form lenalidomide acid addition salts, then water solubility improves, but dissociation increases leading to reduced stability
Solution Approach 1:
The patent optimizes the acid strength parameter by selecting acids with pKa values between -2 and 4, specifically avoiding very strong acids (pKa < -2). This parameter optimization achieves adequate water solubility improvement while minimizing dissociation extent, thereby maintaining formulation stability. The balanced pH range prevents both insufficient solubility and excessive dissociation.
3Object-affected harmful factors
If basic excipients are present in the formulation, then the formulation maintains neutral pH which is generally safe, but proton transfer occurs causing conversion of acid addition salt to free base and deteriorating stability
Solution Approach 1:
The patent applies preliminary anti-action by pre-selecting excipients that cannot accept protons (acids with pKa > 4 or non-basic excipients) before formulation assembly. This preventive measure eliminates the possibility of proton transfer reactions that would convert the acid addition salt to free base, thereby maintaining stability while ensuring pH safety through careful excipient selection.
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 achieves superior storage stability, improved in-vitro dissolution, and processability, maintaining bioavailability and suitability for commercial production.
Implementation Method 1
pharmaceutical composition of lenalidomide pharmaceutically acceptable acid addition salt
Implementation Method 2
excipients which are not capable of accepting proton can enhance the physicochemical stability of lenalidomide
Implementation Method 3
enable the required dissolution and bioavailability of the drug
Data Source
AI summary
The present invention provides solid pharmaceutical formulations and methods for making the same, wherein the pharmaceutical formulations comprise lenalidomide in the form of a pharmaceutically acceptable salt. The pharmaceutical formulations of the present invention exhibit superior stability especially in terms of disproportionation of the lenalidomide salt: this undesired effect is prevented by incorporating an acid into the formulation and/or by avoiding the use of proton-accepting excipients and/or by selecting a combination of excipients such that the resulting formulation exhibits acidic properties.