Buffered Coated Can for pMDI pH Stability
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Solution Overview
Problem
Current pressurized metered dose inhalers (pMDIs) lack a practical method to maintain the apparent pH of formulations containing corticosteroids and long-acting beta agonists (LABAs) with hydrofluoroalkane (HFA) or hydrofluoroolefin (HFO) propellants, affecting stability, shelf life, and consistent medication delivery.
Innovation Solution
An internally coated can with materials like epoxy-phenol resin, perfluorinated polymers, and fluorinated-ethylene-propylene (FEP) coatings acts as a pH buffering system, stabilizing the apparent pH between 2.5 and 5, eliminating the need for external buffering agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If external buffering agents are added to stabilize pH, then pH stability is improved, but formulation complexity and potential degradation increase
Solution Approach 1:
The invention extracts the buffering function from the bulk formulation and relocates it to the canister coating layer. The coating material (fluorinated polymer or epoxy-phenol resin) provides pH buffering capacity specifically at the interface where degradation occurs, eliminating the need for buffering agents throughout the entire formulation.
Solution Approach 2:
The buffering action is localized to the canister interior surface where pH control is most critical for preventing degradation. The coating layer creates a localized buffering zone at the formulation-canister interface, providing pH stability exactly where it is needed without affecting the bulk formulation composition.
2Ease of manufacture
If conventional can materials are used without coating, then manufacturing simplicity is maintained, but particle adhesion and deposition occur
Solution Approach 1:
The invention uses composite material systems where fluorinated polymers or epoxy-phenol resins are applied as coating layers on conventional metal canisters. This composite structure combines the manufacturing simplicity of standard canister fabrication with the particle-repelling properties of the coating material.
Solution Approach 2:
The coating layer acts as an intermediary between the canister surface and the formulation. This intermediate layer prevents direct contact between the formulation particles and the canister surface, eliminating adhesion and deposition while maintaining manufacturing simplicity.
3Reliability
If HFA propellants are used, then efficacy and compatibility are improved, but environmental harm increases
Solution Approach 1:
The invention changes the chemical composition parameters of the canister coating material to provide pH buffering capacity that is specifically effective with HFA propellants. The fluorinated polymer or epoxy-phenol resin coating creates a chemical environment that maintains formulation stability and pH control when used with HFA propellants.
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 coated can maintains stable apparent pH over time, enhancing the stability and reproducibility of the formulation, ensuring consistent aerosol delivery and prolonged shelf life without additional buffering agents, while reducing greenhouse warming potential.
Implementation Method 1
the coated can acts as a pH buffering system, stabilizing the apparent pH between 2.5 and 5
Implementation Method 2
Fluorocarbon polymers are commonly used to coat the interior can surfaces of pMDIs to eliminate particle adhesion, or deposition on can walls
Implementation Method 3
A pMDI device typically presents a medical-containing canister (or a 'can' as herein referred to), and an actuator housing having a mouthpiece... a propellant to expel droplets containing the pharmaceutical products to the respiratory tract as an aerosol
Data Source
AI summary
The present invention generally relates to an aerosol formulation comprising formoterol and beclomethasone dipropionate, said formulation being contained in a coated can, particularly useful for the use in a pressurised metered dose inhaler for the treatment of respiratory diseases.