Elastomeric Stopper Plunger for Lyophilized Drug Carpules
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Solution Overview
Problem
There is a need for an improved system to easily and efficiently deliver drugs that come in two forms, such as lyophilized matter or powder and liquid solvent, which requires premixing, while ensuring sterilizability, using disposable carpules, and allowing for blood aspiration to prevent injection into blood vessels.
Innovation Solution
An elastomeric lyophilization stopper that can be partially inserted into a carpule for freeze-drying and fully inserted as a plunger for injection, facilitating both pre-mixing and injection by sealing and venting functions, and allowing fluid communication during the freeze-drying process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional stopper is used in the carpule, then the carpule can be sealed for freeze-drying, but an additional plunger device is required for injection, increasing device complexity
Solution Approach 1:
The patent combines the stopper and plunger into a single integrated elastomeric component. The stopper plug seals the carpule during freeze-drying, while the plunger rod extends from the stopper to enable fluid injection. This merging eliminates the need for separate stopper and plunger devices, reducing overall device complexity while maintaining both sealing and injection functions.
Solution Approach 2:
The elastomeric stopper-plunger assembly performs multiple functions: it seals the carpule during freeze-drying, allows vapor escape through channels during processing, and subsequently acts as a plunger for injecting the reconstituted medication. This multi-functional design eliminates the need for ancillary equipment and simplifies the overall system.
2Reliability
If the stopper is fully inserted to seal the carpule, then the carpule is hermetically sealed, but fluid communication is blocked during freeze-drying
Solution Approach 1:
The stopper is designed with non-uniform structure: the front end contains vapor escape channels that allow fluid communication during freeze-drying, while the rear end provides sealing when fully inserted. This local differentiation of properties allows the stopper to maintain both vapor escape functionality during processing and hermetic sealing upon completion.
Solution Approach 2:
The stopper transitions between different functional states: during freeze-drying, it maintains a position that allows vapor escape through its channels; after freeze-drying, it can be fully inserted to provide hermetic sealing. The elastomeric material allows dynamic adjustment of the sealing interface with the carpule bead.
3Reliability
If multiple devices are used for pre-mixing and injection, then each function can be optimized, but waste and cross-contamination risks increase
Solution Approach 1:
The patent integrates the pre-mixing and injection functions into a single disposable carpule system with an integrated stopper-plunger. The elastomeric stopper with vapor escape channels serves both the freeze-drying sealing function and the subsequent plunger function for injection. This eliminates the need for multiple devices, reducing waste from discarded equipment and minimizing cross-contamination risks between procedures.
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 efficient and cost-effective pre-mixing and injection of lyophilized drugs with reduced waste, minimizing human error, and avoiding cross-contamination and residual medication, while reducing the need for ancillary equipment.
Implementation Method 1
The freeze-drying process involves freezing the material and then dehydrating the material by reducing the surrounding pressure to allow the frozen water in the material to sublime directly from the solid phase to the gas phase
Implementation Method 2
The lyophilization stopper includes recesses which, when the stopper is partially inserted into a rear opening of an otherwise sealed carpule containing material to be freeze-dried, facilitates fluid communication between the interior of the carpule and the freeze dryer, allowing vapors generated during the lyophilization process to escape from the carpule
Implementation Method 3
When the hollow rod is removed, the elastomeric material of the thin central portion will 'seal itself' around the puncture hole
Implementation Method 4
After the lyophilization operation, shelves provided within the freeze dryer are typically lowered to contact the stopper and then push it deeper into the carpule to a position whereat the evacuated chamber of the carpule, with its dehydrated contents, is sealed for later use
Data Source
AI summary
An elastomeric stopper that can be partially inserted in a rear opening of a glass carpule and that also serves, when fully inserted in the carpule, as a plunger for forcing fluid inside the carpule out through a front opening thereof. The stopper has a thin central portion at its front end that can be readily pierced by a pointed hollow rod of a syringe. When the hollow rod is removed, the elastomeric material of the thin central portion will “seal itself” around the puncture hole. The stopper also has a retractable lip at its rear end that allows the entirety of the stopper to be pushed down and into a fluid-containing glass carpule, thereby acting as a plunger and ejecting fluid from the front opening of the carpule.