Aqueous Capsaicin Injection Formulation for Solubility and Oxidation Stability
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Solution Overview
Problem
Existing capsaicin formulations are poorly soluble in water and unstable for injection, leading to potential oxidation and loss of efficacy during storage and distribution.
Innovation Solution
Use of a polyethylene glycol ester of a long-chain hydroxyalkanoic or hydroxyalkenoic acid, such as KOLLIPHOR HS 15, as a solubilizing agent to enhance capsaicin solubility and stability in aqueous formulations, preventing oxidation and improving storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If capsaicin is formulated in aqueous solution for injection, then the formulation is suitable for parenteral administration and distribution, but capsaicin solubility is poor and stability is insufficient leading to oxidation during storage
Solution Approach 1:
The patent employs antioxidants (such as ascorbic acid, tocopherol, or sulfites) as intermediary substances that prevent oxidation of capsaicin in aqueous formulations. These intermediaries sacrificially react with oxidizing agents or free radicals, protecting the capsaicin molecule from degradation during storage and distribution, thus resolving the contradiction between aqueous suitability and oxidative stability.
Solution Approach 2:
The patent modifies formulation parameters by adjusting pH levels, using chelating agents to bind metal ions that catalyze oxidation, and controlling storage conditions. These parameter changes create an environment that minimizes oxidative reactions while maintaining capsaicin solubility and biological activity in aqueous injectable formulations.
2Duration of action of stationary object
If capsaicin is stored in aqueous formulation during distribution, then the formulation can be transported and administered, but capsaicin degrades through oxidation over time
Solution Approach 1:
The patent incorporates antioxidants and stabilizing agents into the formulation before distribution, performing preliminary protective action against oxidation. This preemptive measure ensures that capsaicin is protected from degradation throughout the distribution and storage period, maintaining efficacy without requiring special handling or reduced storage duration.
3Ease of manufacture
If conventional capsaicin formulations are used, then the formulation is simple to prepare, but solubility in water is poor and injection suitability is compromised
Solution Approach 1:
The patent creates composite aqueous formulations combining capsaicin with solubilizing agents (such as cyclodextrins, surfactants, or cosolvents) and antioxidants. This composite approach maintains ease of manufacture by using compatible ingredients that can be mixed in standard pharmaceutical equipment, while dramatically improving capsaicin solubility and stability in water-based injectable formulations.
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
Achieves higher capsaicin solubility and stability in aqueous solutions suitable for injection, maintaining efficacy and reducing impurity formation.
Implementation Method 1
Use of a polyethylene glycol ester of a long-chain hydroxyalkanoic or hydroxyalkenoic acid, such as KOLLIPHOR HS 15, as a solubilizing agent to enhance capsaicin solubility
Implementation Method 2
polyethylene glycol ester of a long-chain hydroxyalkanoic or hydroxyalkenoic acid... as a solubilizing agent to enhance capsaicin solubility in aqueous formulations
Implementation Method 3
about 0.001% (w/w) to about 2% (w/w) of an antioxidant... preventing oxidation and improving storage stability
Data Source
AI summary
The invention provides stable, aqueous capsaicin injectable formulations, a unit dose containing such injectable formulations, medical kits, and methods for using such injectable formulations and unit doses to treat patients suffering from pain, such as osteoarthritic knee pain. The stable, aqueous capsaicin injectable formulations may contain, for example, capsaicin, a solubilizing agent (e.g., a polyethylene glycol ester of a (C15-C25) hydroxyalkanoic acid), an antioxidant, and water.