Topical Fipronil Permethrin Formulation Stability
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Solution Overview
Problem
Current formulations for combating parasitic infestations, particularly those involving ectoparasites like stable flies and ticks, face challenges in achieving effective solvency, stability, and bioavailability, leading to inconsistent results and the need for more effective topical formulations that can maintain active ingredient concentrations and prevent oxidation of fipronil to fipronil sulfone.
Innovation Solution
A stable topical formulation combining permethrin and fipronil with a solvent system comprising N-methyl pyrrolidone and a glycol, glycol ether, glycol ester, or neutral oil, which limits fipronil oxidation and maintains effective concentrations, providing enhanced repellency and parasiticidal activity against stable flies and other ectoparasites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional solvent systems are used in topical formulations, then the formulations can be manufactured, but the active ingredient concentrations cannot be maintained and fipronil oxidizes to fipronil sulfone
Solution Approach 1:
The patent changes the chemical parameters of the solvent system by specifying precise ratios of N-methyl pyrrolidone (25-44%) combined with specific glycols, glycol ethers, glycol esters, or neutral oils (11-18%). This parameter optimization prevents fipronil oxidation to sulfone while maintaining formulation stability and active ingredient concentrations.
Solution Approach 2:
The patent employs a composite solvent system combining N-methyl pyrrolidone with specific glycols, glycol ethers, glycol esters, or neutral oils in defined ratios. This composite approach provides both solvency for the active ingredients and stability to prevent oxidation, resolving the contradiction between formulation manufacturability and chemical stability.
2Quantity of substance
If high concentrations of active ingredients are used to achieve effective parasiticidal activity, then efficacy improves, but solvency and stability become difficult to maintain
Solution Approach 1:
The patent optimizes the concentration parameters of active ingredients (permethrin 30-55% and fipronil 2-15%) within specific ranges that maintain solvency and stability. The solvent system parameters are also precisely controlled to match the active ingredient concentrations, ensuring both high efficacy and formulation stability are achieved simultaneously.
Solution Approach 2:
The patent uses the solvent system (N-methyl pyrrolidone combined with glycols, glycol ethers, glycol esters, or neutral oils) as an intermediary that enables high concentrations of active ingredients to be maintained without compromising stability. The solvent system acts as a mediator between the high active ingredient load and formulation stability requirements.
3Reliability
If the formulation is designed to provide excellent solvency for active ingredients, then bioavailability improves, but excessive fipronil sulfone formation occurs
Solution Approach 1:
The patent changes the chemical environment parameters by selecting specific solvent combinations (N-methyl pyrrolidone with glycols, glycol ethers, glycol esters, or neutral oils in defined ratios) that provide excellent solvency for bioavailability while simultaneously suppressing the oxidation pathway that generates harmful fipronil sulfone.
Solution Approach 2:
The patent converts the potentially harmful effect of N-methyl pyrrolidone (which can promote oxidation) into a beneficial system by carefully controlling its concentration (25-44%) and combining it with stabilizing agents (glycols, glycol ethers, glycol esters, or neutral oils). This transforms the oxidation risk into a controlled system that provides both solvency and stability.
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 unexpected enhanced repellency and superior efficacy against stable flies and other ectoparasites by maintaining active ingredient solubility and stability, preventing excessive fipronil sulfone formation, and ensuring effective concentrations post-administration.
Implementation Method 1
The solvent system of the formulations provide excellent solvency and reduce the amount of fipronil sulfone formation over a wide range of conditions
Implementation Method 2
maintain active ingredient solubility and stability, preventing excessive fipronil sulfone formation
Data Source
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AI summary
The subject matter disclosed herein is directed to stable, highly-effective topical formulations comprising permethrin, fipronil and a solvent system that is sufficient to solubilize these two active ingredients and limit degradation of fipronil to its sulfone, and their uses in topical applications on animals and the environment. Useful formulations comprise from about 30 % to about 55 % (w/w) permethrin and about 2 to 15 % (w/w) fipronil and a solvent system that comprises N-methyl pyrrolidone and a glycol, glycol ether, glycol ester, fatty acid ester or neutral oil, wherein the N-methyl pyrrolidone and glycol, glycol ether, glycol ester, fatty acid ester or neutral oil are present in a weight: weight ratio of from about 1:2.0 to about 1:3.5, glycol, glycol ether, glycol ester, fatty acid ester or neutral oil to n-methyl pyrrolidone. These two actives when combined in the described amounts have been found to have unexpected enhanced repellent activity against stable fly. However, it is the formulations described herein that provide solvency and stability that maintain synergistic concentrations after application on an animal.