Stable Paracetamol Injection via Cyclodextrin and Antioxidant Complex
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Solution Overview
Problem
Paracetamol solutions for intravenous administration are unstable in aqueous media due to chemical oxidation and deacetylation, leading to degradation and the formation of hepatotoxic compounds, making it challenging to develop a stable, transparent injectable formulation.
Innovation Solution
A pharmaceutical composition with an optimal pH of 6.0 (ranging between 5.5 and 6.5) comprising paracetamol, 2-hydroxypropyl-beta-cyclodextrin, monothioglycerol, and EDTA, which stabilizes and solubilizes paracetamol, preventing degradation and maintaining solution clarity, even at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If paracetamol is dissolved in aqueous medium for intravenous administration, then it becomes available for parenteral use, but it degrades through oxidation and deacetylation leading to solution instability and formation of hepatotoxic compounds
Solution Approach 1:
The patent employs multiple intermediary substances that mediate between paracetamol and the aqueous environment. Cyclodextrins form inclusion complexes with paracetamol, shielding it from water and oxygen. Antioxidants (ascorbic acid, alpha-tocopherol, monothioglycerol) mediate protection against oxidative degradation. These intermediaries collectively prevent direct interaction between paracetamol and degrading agents, resolving the contradiction between solubility and stability.
Solution Approach 2:
The invention creates a composite pharmaceutical formulation combining paracetamol with multiple stabilizing components: cyclodextrins (solubilizing agents), antioxidants (oxidation protectors), and buffering agents (pH controllers). This composite system provides synergistic protection, allowing paracetamol to remain stable in aqueous solution while maintaining its therapeutic efficacy and parenteral administrability.
2Ease of operation
If paracetamol solution is stored at room temperature for long periods, then convenience of storage is improved, but degradation and color formation occur reducing product reliability
Solution Approach 1:
The formulation incorporates preliminary protective actions by pre-incorporating antioxidants, cyclodextrins, and buffering agents into the solution before storage. These pre-installed protective mechanisms actively prevent degradation during storage, allowing the product to maintain reliability at room temperature without requiring refrigeration or special storage conditions.
Solution Approach 2:
The patent optimizes multiple formulation parameters simultaneously: pH is adjusted to 5.0-7.0 (optimal stability range), antioxidant concentrations are precisely controlled (0.01-0.1% w/v), and cyclodextrin:paracetamol ratios are optimized (1:1 to 10:1). These parameter optimizations collectively enable room temperature storage while maintaining product reliability for extended periods.
3Stability of the object's composition
If antioxidants and stabilizing agents are added to prevent degradation, then solution stability is improved, but formulation complexity increases
Solution Approach 1:
The formulation employs multi-functional substances that perform multiple roles simultaneously. Cyclodextrins not only solubilize paracetamol but also protect against oxidation and hydrolysis. Buffering agents maintain pH while potentially providing additional stabilization. This multi-functionality reduces the need for separate additives, managing formulation complexity while maintaining stability.
Solution Approach 2:
The patent establishes specific concentration ranges and ratios that optimize stability while controlling complexity. Antioxidants are present at 0.01-0.1% w/v, cyclodextrin:paracetamol ratios are maintained at 1:1 to 10:1, and pH is controlled at 5.0-7.0. These defined parameters provide a standardized formulation approach that balances stability enhancement with manageable complexity.
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 composition remains stable for over 24 months at room temperature and 3 months at 40°C without visible color or particulate matter, allowing for non-refrigerated storage and use in clear glass or polymer containers, ensuring safety and efficacy of the intravenous paracetamol solution.
Implementation Method 1
comprising at least one stabilizing and one dissolving substance of paracetamol in solution such as a cyclodextrin
Implementation Method 2
one stabilizing and one dissolving substance of paracetamol in solution such as a cyclodextrin, EDTA, monothioglycerol (MTG)
Implementation Method 3
comprising at least one stabilizing and one dissolving substance of paracetamol in solution such as a cyclodextrin, EDTA
Implementation Method 4
Establishing an optimal pH in which the formation of 4-aminophenol is prevented or minimized, as has been indicated by K. Thomas Koshy and Jon L. Lach in the previous indicated reference, the hydrolysis of the acetate group of paracetamol is minimized between pH= 4.5 and pH 6.0
Data Source
AI summary
The invention concerns a stable aqueous paracetamol solution for use in IV infusion comprising at least one stabilizing-dissolving compound for paracetamol in solution selected from the group consisting of hydroxyalkyl-cyclodextrins and at least one stabilizing compound, being EDTA or monothioglycerol, alone or in combination, in a concentration between 0.001% and 20 % m/v.