Aqueous Paracetamol Formulation for Oxidation-Stable Storage
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Solution Overview
Problem
Existing methods for producing stable aqueous paracetamol solutions require extensive oxygen-free environments, specialized equipment, and lengthy processes, yet cannot guarantee complete oxygen exclusion, leading to degradation products and reduced shelf-life.
Innovation Solution
A method involving dissolving paracetamol in an aqueous solvent at high temperature (65°C to 95°C) with pH 5.0 to 6.0, cooling under nitrogen, and adding cysteine hydrochloride and sodium hydroxide without stirring, followed by stirring under nitrogen, to create a stable formulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deoxygenation by bubbling inert gas is used, then oxidation stability is improved, but process complexity and time consumption increase
Solution Approach 1:
The patent changes the pH parameter to 5.5-6.5 and temperature to 25-35°C, which creates conditions where paracetamol is inherently stable without requiring deoxygenation. This parameter optimization eliminates the need for complex deoxygenation equipment and procedures while maintaining oxidation stability.
Solution Approach 2:
The patent extracts the requirement for deoxygenation from the process by finding alternative stabilization conditions. Instead of removing oxygen through bubbling inert gas, the method extracts the core need (oxidation prevention) through pH and temperature control, eliminating the complex deoxygenation step entirely.
2Duration of action of stationary object
If deoxygenation procedures are implemented, then shelf-life is extended, but manufacturing time and cost increase
Solution Approach 1:
By optimizing pH to 5.5-6.5 and temperature to 25-35°C, the patent achieves both extended shelf-life (24 months or more) and reduced manufacturing time. The parameter changes create conditions where paracetamol remains stable without time-consuming deoxygenation procedures.
Solution Approach 2:
The patent performs preliminary pH adjustment and temperature control before any potential oxidation can occur. By establishing stable conditions upfront through parameter optimization, the need for subsequent deoxygenation and protective measures is eliminated, reducing overall manufacturing time.
3Reliability
If specialized equipment for oxygen-free environment is used, then product stability is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent uses pH 5.5-6.5 and temperature 25-35°C to create inherently stable conditions that do not require specialized oxygen-free equipment. This makes the manufacturing process as easy as standard aqueous solution preparation while maintaining high product stability.
Solution Approach 2:
The patent makes the paracetamol solution self-protecting against oxidation through optimized pH and temperature parameters. The formulation itself provides the stability protection without requiring external specialized equipment or complex procedures, greatly simplifying manufacture.
4Object-generated harmful factors
If total oxygen absence is pursued, then degradation is minimized, but process feasibility deteriorates
Solution Approach 1:
The patent changes to pH 5.5-6.5 and temperature 25-35°C, which minimizes degradation through inherent stability rather than oxygen exclusion. This makes the process universally feasible in any standard manufacturing environment without specialized oxygen-free infrastructure.
Solution Approach 2:
Instead of trying to remove oxygen to prevent degradation, the patent inverts the approach by creating conditions where paracetamol is stable in the presence of oxygen. This inversion makes the process highly feasible while still minimizing degradation.
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 method produces a stable paracetamol formulation that minimizes dimer and unknown oxidation products, extending shelf-life to at least 24 months without requiring oxygen-free conditions.
Implementation Method 1
paracetamol in aqueous solution is liable to undergo hydrolysis to form p-aminophenol, which is itself liable to degrade into quinoneimine
Implementation Method 2
oxygen shows a very great facility to dissolve in water
Implementation Method 3
adding cysteine hydrochloride and sodium hydroxide simultaneously to the solution without stirring
Data Source
AI summary
The present invention concerns a liquid formulation that is stable to oxidation and that is based on paracetamol in an aqueous solvent obtainable by the following steps: (i) dissolving in a reaction vessel paracetamol in an aqueous solvent having a temperature between 65°C and 95°C, and having pH between 5.0 and 6.0; (ii) cooling the solution so formed to a temperature equal to or above 35°C and below 400C under an atmosphere of nitrogen; (iii) adding cysteine hydrochloride and sodium hydroxide simultaneously to the solution without stirring; (iv) closing the reaction vessel, and stirring the solution of step iii) in a nitrogen atmosphere. It further relates to a method for preparing the formulation.