Aqueous Gel Topical Anesthesia Formulation
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Solution Overview
Problem
Current anesthetic agents for topical administration, such as subconjunctival injections of lidocaine and tetracaine drops, face issues like anxiety, pain, inefficacy due to short residence time, and potential toxicity, necessitating a more effective formulation for rapid and prolonged anesthesia with reduced anxiety and pain.
Innovation Solution
An aqueous gel formulation comprising water, an anesthetic (like lidocaine), a viscoelastic polymer (e.g., hydroxypropylmethylcellulose), and a tonicity modifier (e.g., sodium chloride), free of preservatives and phosphate buffer, designed for topical application to increase residence time and anesthetic duration, with a pH adjusted to minimize irritation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If subconjunctival injections of aqueous lidocaine are used, then anesthesia is achieved, but patient anxiety and pain increase due to needle phobia and injection pain
Solution Approach 1:
The patent introduces a gel carrier as an intermediary substance that delivers the anesthetic agent without requiring direct needle injection into sensitive tissues. The gel formulation allows topical application, serving as a mediator between the anesthetic and the target tissue, thereby eliminating injection-related anxiety and pain while maintaining anesthetic efficacy.
Solution Approach 2:
The patent changes the physical state of the anesthetic delivery system from an injectable aqueous solution to a topical gel formulation. This parameter change in delivery method transforms the administration route from invasive injection to non-invasive topical application, reducing patient anxiety and pain while preserving the anesthetic effect.
2Ease of operation
If tetracaine drops are used for topical administration, then needle-related problems are avoided, but residence time on the eye is limited to less than one minute
Solution Approach 1:
The patent changes the physical properties of the topical formulation by incorporating gel-forming polymers, which increase viscosity and residence time on the ocular surface. This parameter change transforms the formulation from a rapidly draining liquid drop to a sustained-release gel, extending contact time while maintaining ease of topical application.
Solution Approach 2:
The patent creates a composite formulation by combining the anesthetic agent with gel-forming polymers and other excipients. This composite material structure provides both the therapeutic anesthetic effect and the extended residence time property, overcoming the limitation of simple aqueous drops while preserving topical applicability.
3Ease of operation
If tetracaine drops are used, then topical administration is achieved, but anesthetic onset is not rapid and duration is limited
Solution Approach 1:
The patent optimizes multiple parameters of the formulation including anesthetic concentration, gel viscosity, and polymer composition to achieve both rapid onset and prolonged duration. By adjusting these parameters, the formulation delivers fast anesthetic action while maintaining extended residence time on the ocular surface, eliminating the time loss associated with conventional drops.
Solution Approach 2:
The patent ensures continuous anesthetic action by creating a gel formulation that maintains sustained contact with the ocular surface. The gel matrix provides continuous release of the anesthetic agent over an extended period, eliminating the interruptions and repeated applications needed with conventional drops, thereby reducing total time loss.
4Reliability
If conventional anesthetic formulations are used, then anesthesia is provided, but corneal toxicity may occur
Solution Approach 1:
The patent changes the chemical composition parameters of the formulation by selecting anesthetic agents and excipients with improved safety profiles. The gel formulation uses lower concentrations of potentially toxic substances and incorporates cornea-safe polymers, maintaining anesthetic efficacy while reducing corneal toxicity risks compared to conventional formulations.
Solution Approach 2:
The patent employs a single-use disposable gel formulation that eliminates the need for preservatives and long-term storage. This disposable approach uses sterile, biocompatible materials that are safe for corneal contact, reducing toxicity risks associated with preservative-containing multi-use formulations while maintaining reliable anesthetic action.
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 rapid onset and prolonged anesthesia, reducing anxiety and pain, with increased safety and stability, suitable for various medical procedures without the need for subsequent injections, and is less toxic to the cornea compared to tetracaine.
Implementation Method 1
The formulation includes a viscoelastic polymer which increases the residence time of the formulation on the tissue or organ
Implementation Method 2
The formulation may also contain a pH adjusting agent or a product produced as a result of pH adjustment
Implementation Method 3
The aqueous gel formulation is free of preservatives and phosphate buffer, is isotonic with physiological fluids
Data Source
AI summary
Disclosed is a stable aqueous gel formulation suitable for topical use comprising water, an anesthetic (e.g., lidocaine hydrochloride), a viscoelastic polymer, and a tonicity modifier, wherein the aqueous gel formulation is free of preservatives and phosphate buffer, is isotonic with physiological fluids, and is sterile and has low particulate count. Also disclosed is a method of inducing topical anesthesia on a tissue or organ, e.g., the eye, of an animal comprising providing a stable aqueous gel formulation comprising water, an anesthetic, a viscoelastic polymer, and a tonicity modifier, wherein the aqueous gel formulation is free of preservatives and phosphate buffer, is isotonic with physiological fluids, and is sterile, and topically administering an effective amount of the aqueous gel formulation to the tissue or organ of the animal.