Multi-Acid Aqueous Anesthetic Formulation for High Solubility
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Solution Overview
Problem
Existing anesthetic formulations for poorly soluble drugs like bupivacaine and ropivacaine face limitations in solubility, leading to large and cumbersome infusion pumps for continuous administration, and can cause local injection site irritation due to acidic formulations.
Innovation Solution
A stable aqueous formulation of free-base anesthetics using a combination of three or more acids, such as acetic, phosphoric, and hydrochloric acid, to achieve solubilization of 100 mg/mL or more of the drug, reducing irritation and enabling smaller pump sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional solubilizing approaches using solvents, surfactants and co-solvents are used, then solubility of poorly soluble drugs is improved, but device complexity and formulation complexity increase
Solution Approach 1:
The patent removes traditional solubilizing excipients (surfactants, co-solvents, lipids) from the formulation and extracts only the essential component: acid. This simplifies the formulation while maintaining enhanced solubility through acid-mediated mechanisms.
Solution Approach 2:
The patent employs a composite acid system combining multiple acids (e.g., citric acid, acetic acid, hydrochloric acid) to achieve synergistic solubilization effects, allowing high drug concentration without traditional complex excipients.
2Quantity of substance
If acidic formulations are used to increase solubility of basic drugs, then solubility is improved, but local injection site irritation increases
Solution Approach 1:
The patent optimizes acid concentration parameters and pH levels to achieve the minimum acidity required for solubilization while staying below thresholds that cause significant injection site irritation. The multi-acid system allows fine-tuning of these parameters.
Solution Approach 2:
By combining multiple acids with different properties (weak and strong acids), the formulation achieves effective solubilization with a more balanced pH profile compared to using a single strong acid, thereby reducing irritation while maintaining solubility.
3Object-affected harmful factors
If low concentration solutions are used for continuous infusion, then injection site irritation is reduced, but pump size increases due to large required volume
Solution Approach 1:
The patent dramatically changes the concentration parameter of the drug solution, achieving 100-fold or greater increases in solubility. This allows therapeutic doses to be delivered in much smaller volumes, enabling use of compact ambulatory pumps.
4Volume of moving object
If high concentration formulations are used to reduce pump size, then pump size is reduced, but solubility limitations are exceeded
Solution Approach 1:
The patent changes the chemical environment parameters by introducing a multi-acid system that fundamentally alters the solubility characteristics of basic drugs, enabling high concentrations (100 mg/mL or greater) that were previously unachievable.
Solution Approach 2:
The composite acid system creates a unique chemical environment that enhances drug solubility beyond what single acids or traditional excipients can achieve, allowing formulation of highly concentrated solutions.
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 provides enhanced solubility and reduced irritation, allowing for effective analgesia in smaller volumes with comparable efficacy to traditional formulations, reducing pump size by up to 95% and minimizing side effects.
Implementation Method 1
Because both ropivacaine and bupivacaine are basic molecules, lowering the pH of the formulation to obtain various salt forms can have the desired effect of increasing the drug solubility in aqueous media.
Implementation Method 2
The solubility of bupivacaine hydrochloride monohydrate has been reported to be 40-50 mg/mL in water between pH 1.8 and 6.
Data Source
AI summary
This invention describes compositions comprising at least 75 mg/mL of solubilized otherwise poorly soluble drug in an aqueous environment, wherein the composition further comprises a combination of 3 or more acids. Methods of providing analgesia, anti-pyretic effects or reducing pain in a subject presenting with a pain condition, and methods of reducing administration site irritation, inflammation or a combination thereof in a subject presenting with a pain condition, comprising the steps of administering such compositions and infusion pumps containing such compositions are also described.