High-Pressure Measurement Cell for pMDI Propellant Analysis
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Solution Overview
Problem
The stability of therapeutic suspensions in pressurized metered-dose inhalers (pMDIs) is challenging due to the rapid boiling of propellants at standard atmospheric pressure and temperature, making it difficult to measure electrophoretic mobility and particle size, which are crucial for assessing colloidal stability and ensuring drug efficacy and safety.
Innovation Solution
A high-pressure measurement system capable of retaining pMDI propellants in a liquid state, using a measurement cell designed to operate at pressures up to 700 kPa, combined with a bubble mitigation system and a rapid release adapter to inject the pressurized liquid sample into the measurement device, allowing for accurate electrophoretic mobility and particle size analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard atmospheric pressure and temperature are used for measurement, then the measurement system is simple and easy to operate, but the propellant rapidly boils and cannot maintain liquid state, making electrophoretic mobility and particle size measurement impossible
Solution Approach 1:
The patent applies parameter changes by increasing the pressure parameter from standard atmospheric pressure to high pressure (up to 700 kPa) to maintain the propellant in liquid state during measurement. This pressure parameter change prevents rapid boiling and enables accurate electrophoretic mobility and particle size measurements that would otherwise be impossible under atmospheric conditions.
Solution Approach 2:
The patent implements beforehand cushioning by pre-establishing a high-pressure measurement system capable of withstanding up to 700 kPa before the actual measurement occurs. The measurement cell and associated equipment are designed and prepared in advance to maintain the required pressure conditions, preventing boiling during the measurement process.
2Reliability
If high pressure measurement system is used to retain propellant in liquid state, then electrophoretic mobility and particle size can be measured accurately, but the device complexity and cost increase
Solution Approach 1:
The patent applies universality by designing a high-pressure measurement system that can perform multiple functions: maintaining propellant in liquid state, enabling electrophoretic mobility measurement, and conducting particle size analysis. The same high-pressure cell and equipment serve all these purposes, reducing the need for separate specialized devices for each function.
Solution Approach 2:
The patent uses an intermediary approach by introducing a high-pressure measurement cell as a mediator between the propellant sample and the measurement instruments. This intermediary device maintains the required pressure conditions and allows accurate measurements without requiring the propellant to be in a specific state or the measurement equipment to be overly complex.
3Measurement precision
If propellant is kept in liquid state at high pressure, then accurate measurements can be performed, but the measurement time and pressure maintenance requirements increase
Solution Approach 1:
The patent applies continuity of useful action by maintaining high pressure throughout the entire measurement process to keep the propellant in liquid state continuously. This continuous pressure maintenance ensures consistent measurement conditions without interruptions, allowing for accurate and reliable particle size and electrophoretic mobility measurements.
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
Enables precise measurement of electrophoretic mobility and particle size of pMDI suspensions, ensuring quality assurance and evaluating the suitability and longevity of propellants, thereby improving drug delivery and safety for COPD patients.
Implementation Method 1
A high-pressure measurement system capable of retaining pMDI propellants in a liquid state, using a measurement cell designed to operate at pressures up to 700 kPa
Implementation Method 2
a rapid release adapter to inject the pressurized liquid sample into the measurement device
Implementation Method 3
enables precise measurement of electrophoretic mobility and particle size of pMDI suspensions
Data Source
AI summary
A method and apparatus for measuring the physical properties of a drug formulation suspended in a pressurized liquid propellant and a system to enable such measurements is disclosed. Drug formulations suspended in pressurized liquid propellant used in Pressurized Metered Dose Inhalers (pMDIs) are propelled in their native liquid state into an analytical instrument with a measurement cell capable of withstanding the pressure required to retain the sample in liquid form by employing a device to rapidly release the contents of the pMDI canister into the measurement instrument wherein the sample's electrophoretic mobility and size may be determined by MP-PALS or other techniques. A series of valves permits the maintenance of the high pressure in the system. Once the measurements are made, the pressurized liquid is allowed to pass to waste or another analytical instrument by opening an exit valve.