Desiccant-Entrained Valve Material for pMDI Moisture Control
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Solution Overview
Problem
Pressurized metered dose inhalers (pMDIs) face challenges in maintaining the stability of fine particle mass (FPM) due to moisture ingress, which affects the consistency of drug delivery over the shelf-life, especially under high humidity and temperature conditions, and existing solutions like moisture-impermeable overwraps provide limited protection once the device is removed.
Innovation Solution
Incorporating a desiccant-entrained material within the pMDI closed container system, specifically in the metering valve assembly, to capture moisture and maintain the stability of the FPM without the need for a moisture-impermeable overwrap, ensuring consistent drug delivery over extended storage periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a moisture-impermeable overwrap is used to protect the pMDI, then moisture ingress is prevented during storage, but the protection is limited once the device is removed from the overwrap
Solution Approach 1:
The moisture protection function is extracted from the external overwrap and integrated into the pMDI device itself through the desiccant material. This allows the device to maintain moisture protection independently without relying on an external overwrap, thereby extending the duration of protection throughout the entire shelf-life of the product.
Solution Approach 2:
A desiccant material is introduced as an intermediary component within the closed container system to actively manage moisture. This desiccant acts as a mediator between the formulation and the external environment, absorbing moisture that penetrates through the container walls and maintaining stable FPM throughout storage.
2Loss of time
If the pMDI is stored under high humidity and temperature conditions, then shelf-life testing is accelerated, but FPM stability deteriorates
Solution Approach 1:
The desiccant material is pre-installed within the closed container system before storage, providing advance protection against moisture ingress. This beforehand cushioning allows the device to withstand accelerated storage conditions (high humidity and temperature) without FPM deterioration, enabling reliable shelf-life testing while maintaining composition stability.
3Device complexity
If no desiccant material is used, then the device structure is simpler, but FPM stability cannot be maintained over extended storage periods
Solution Approach 1:
The desiccant material utilizes porous structure to provide effective moisture absorption capacity. The porous nature of the desiccant allows it to capture moisture molecules efficiently while occupying minimal space within the closed container system, thereby extending FPM stability without significantly increasing device 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 desiccant-entrained material effectively stabilizes the FPM, maintaining consistency even under harsh storage conditions (40°C/75% RH for 6 months or 30°C/65% RH for 9-12 months), equivalent to an 18-month shelf-life at standard storage conditions, by managing moisture levels within the formulation.
Implementation Method 1
a water permeable polymer body which contains a desiccant to capture water molecules within the body
Implementation Method 2
a desiccant to capture water molecules within the body
Implementation Method 3
the propellant rapidly vaporises leaving a fast moving cloud of drug particles
Implementation Method 4
the channelling agent which facilitates the transmission of water into the body
Data Source
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AI summary
In one aspect of the invention there is provided use of a desiccant-entrained material of the type defined herein in a pMDI closed container system to stabilise the fine particle mass of an inhalation drug formulation emitted by the system. The material may be in a component of the metering valve assembly 50, such as the gathering ring 18.