Nitroimidazole Gel Composition Stabilized by Organic Acids
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current aqueous compositions of nitroimidazoles like metronidazole and tinidazole face challenges due to limited solubility in water, leading to the presence of insoluble crystals and the need for organic co-solvents or cyclodextrins, which are undesirable in higher concentration formulations.
Innovation Solution
Aqueous compositions that include a nitroimidazole at concentrations higher than its solubility limit in water, stabilized by a crystallization-inhibiting amount of organic acids such as acetic acid or citric acid, without organic co-solvents or cyclodextrins, and optionally thickened with hydroxypropyl methylcellulose or polyacrylic acid to form a gel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nitroimidazole concentration is increased above solubility limit, then therapeutic effectiveness is improved, but nitroimidazole crystals precipitate
Solution Approach 1:
The patent uses organic acids (acetic acid, citric acid, tartaric acid, malic acid) as intermediary substances to mediate between nitroimidazole and water. These acids form soluble complexes with nitroimidazole, enabling higher concentrations to remain in solution without crystallizing. The organic acid acts as a bridge that allows the nitroimidazole to dissolve beyond its normal solubility limit while maintaining solution stability.
Solution Approach 2:
The patent changes the pH parameter of the aqueous solution by adding organic acids, which shifts the equilibrium and increases nitroimidazole solubility. By adjusting the pH to acidic ranges (pH 3-6), the nitroimidazole remains in its protonated, water-soluble form rather than precipitating as crystals. This parameter change allows concentration increases while maintaining stability.
2Quantity of substance
If organic co-solvents or cyclodextrins are added to increase solubility, then nitroimidazole dissolution is improved, but composition complexity and potential adverse effects increase
Solution Approach 1:
Instead of adding complex co-solvents or cyclodextrins, the patent simply changes the pH parameter by adding straightforward organic acids. This single parameter change (pH adjustment) achieves the solubility enhancement without introducing complex formulation components. The approach maintains simplicity while effectively increasing nitroimidazole dissolution.
Solution Approach 2:
The patent employs simple, inexpensive organic acids (acetic acid, citric acid) that are readily available and easily handled. These basic substances replace expensive or complex co-solvents and cyclodextrins, providing an economical and simple solution for enhancing nitroimidazole solubility without adding formulation complexity.
3Quantity of substance
If organic co-solvents are used to achieve higher concentrations, then nitroimidazole solubility is improved, but physiological safety and composition purity are compromised
Solution Approach 1:
The patent uses simple organic acids (acetic acid, citric acid, tartaric acid, malic acid) that are physiologically safe and commonly found in biological systems. These benign substances replace potentially harmful organic co-solvents, enabling high nitroimidazole concentrations while maintaining physiological safety. The chosen acids have favorable safety profiles and do not introduce adverse effects.
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 compositions achieve higher solubility and stability of nitroimidazole, eliminating crystals and enabling effective treatment of bacterial and protozoal infections and dermatologic conditions without adverse physiological effects.
Implementation Method 1
a nitroimidazole crystallization-inhibiting amount of at least one organic acid
Data Source
AI summary
An aqueous nitroimidazole composition comprises metronidazole, tinidazole or a combination thereof at a concentration greater than the solubility of the free base form of the nitroimidazole in water at 20° C., and a nitroimidazole crystallization-inhibiting amount of at least one organic acid. The organic acid preferably is a lower alkyl carboxylic acid (e.g., acetic acid), a polybasic acid (e.g., citric acid, tartaric acid, malic acid, polyacrylic acid, and the like), or a combination thereof. The composition can further include a thickening agent, to form a gel. The composition is free from organic co-solvents, water-soluble vitamins, and cyclodextrins; and free from nitroimidazole crystals at an ambient temperature of about 20° C. Methods of preparing the composition are also described.