Convertible plungers and methods for assembling the same in a medical barrel
Inventors
Lilly, Brian Russell • Kelly, Kenneth Wade • Rogers, Joseph W. • Giraud, Jean-Pierre • Rabinne, Bruce • Pichot, Herve • Hunt, Benjamin • Freeman, Zachary Dean • Roe, Dalton • Abrams, Robert S.
Assignees
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Publication Number
US-11896807-B2
Publication Date
2024-02-13
Expiration Date
Abstract
Disclosed are plunger assemblies including various convertible plungers and methods of making the same. Each plunger assembly is configured for disposition within a barrel of a medical container, e.g., a syringe, and displaced within the barrel from an engagement position to a release position. The engagement position is configured to provide a compression seal between a storage sealing section of the plunger and an inner wall of the syringe barrel. In the release position, the compression seal is reduced or eliminated. Also disclosed are methods for making convertible plungers and assembling them into syringes, e.g., pre-filled syringes.
Core Innovation
The invention provides a convertible plunger configured to operate in a storage mode and a dispensing mode by changing a condition of a liquid sealing section relative to an interior wall of a medical barrel. The convertible plunger includes first and second subassemblies, with a connector body and a separate plunger head assembled to a distal end of the connector body, and an elongate ring carrier secured to the proximal end of the first subassembly and configured to be secured to a plunger rod.
The ring carrier includes an annular dispensing platform and an annular storage platform distal to the dispensing platform, where the storage platform has a larger maximum diameter or cross-sectional width than the dispensing platform and is more rigid than a compressible and resilient storage ring disposed about the ring carrier and configured to displace axially thereon. An annular insertion platform distal to the storage platform has a smaller maximum diameter or cross-sectional width than the storage platform and is disposed in a recess or axial channel to fixedly secure the subassemblies.
In storage mode, the storage sealing section is maintained in an expanded state by outward radial pressure provided by the storage platform, creating compression between the storage sealing section and the inner wall of the barrel. The expanded state is reducible to a constricted state upon transitioning the storage ring to being disposed about the dispensing platform, thereby reducing or eliminating the compression and rendering the convertible plunger in dispensing mode.
The disclosure also emphasizes an oil-free solution, including an absence of flowable lubricant between a barrel wall and the plunger, to avoid silicone-oil particle/protein degradation and associated immune-response risks for biologics, and it describes optional use of a fluoropolymer film on the liquid sealing section.
Claims Coverage
The provided content includes three independent claims, covering a convertible plunger construction with specific subassemblies and rigidity/compressibility relationship, a pre-filled syringe employing the convertible plunger in storage and dispensing modes with expanded-to-constricted sealing transition, and a convertible plunger with an explicitly symmetric outer surface geometry for the storage ring in an uncompressed state.
Two-subassembly convertible plunger with rigid storage platform and compressible storage ring
A convertible plunger comprising a connector-body first subassembly with a separate plunger head that provides a liquid seal against an interior wall of a medical barrel; an elongate ring-carrier second subassembly with an annular dispensing platform, an annular storage platform distal thereto having a larger maximum diameter or cross-sectional width than the dispensing platform, and an annular insertion platform distal to the storage platform having a smaller maximum diameter or cross-sectional width than the storage platform, where the insertion platform is disposed in a recess or axial channel to fixedly secure the subassemblies; and a compressible and resilient storage ring disposed about the ring carrier and configured to displace axially thereon, wherein the storage platform is more rigid than the storage ring.
Pre-filled syringe with storage-mode expanded seal and dispensing-mode constricted seal
A pre-filled syringe comprising a medical barrel with an inner wall and an injectable drug product disposed in a product containing area, the medical barrel having a distal dispensing end and an open proximal end configured for receipt of a convertible plunger; and a convertible plunger disposed within the medical barrel, where the convertible plunger includes a first subassembly with a connector body and a separate plunger head having a liquid sealing section configured to contact and provide a seal against an interior wall of a medical barrel, and a second subassembly with an elongate ring carrier having an annular dispensing platform and an annular storage platform distal to the dispensing platform, the storage platform having a larger maximum diameter or cross-sectional width than the dispensing platform, and a compressible and resilient storage ring disposed about the ring carrier and configured to displace axially thereon; wherein the storage platform is more rigid than the storage ring; and wherein the storage sealing section, when the storage ring is disposed about the storage platform, is maintained in an expanded state by outward radial pressure provided by the storage platform to create compression between the storage sealing section and the inner wall of the barrel, rendering the convertible plunger in storage mode, the expanded state being reducible to a constricted state upon transitioning the storage ring to being disposed about the dispensing platform whereupon the compression between the storage sealing section and the inner wall of the barrel is reduced or eliminated, thereby rendering the convertible plunger in dispensing mode.
Convertible plunger with symmetric uncompressed storage-ring outer surface
A convertible plunger comprising a connector-body first subassembly with a separate plunger head having a liquid sealing section configured to contact and provide a seal against an interior wall of a medical barrel; and an elongate ring carrier second subassembly with an annular dispensing platform and an annular storage platform distal to the dispensing platform, where the annular storage platform has a larger maximum diameter or cross-sectional width than the dispensing platform, and a compressible and resilient storage ring disposed about the ring carrier and configured to displace axially thereon; wherein the storage ring comprises an outer surface facing generally radially outward away from the ring carrier, and when the storage ring is in an uncompressed state the outer surface comprises a proximal end, a distal end and a radial plane of symmetry between the proximal and distal ends that is equidistant from the proximal and distal ends, wherein the outer surface is symmetrical on either side of the radial plane of symmetry; and wherein the storage platform is more rigid than the storage ring.
Across the independent claims, the main inventive coverage centers on a convertible plunger that uses outward radial pressure from a more rigid annular storage platform to maintain an expanded sealing condition in a storage mode and switches to a constricted sealing condition by relocating the compressible and resilient storage ring to a dispensing platform. The claims further specify the construction using a separate plunger head and a two-subassembly connector-body/ring-carrier arrangement, and in one claim require a symmetric outer-surface geometry for the storage ring in an uncompressed state.
Stated Advantages
Provides container-closure integrity (CCI) with gas-tight sealing in a storage mode.
Switching to a dispensing mode reduces or eliminates compression between the liquid sealing section and the barrel inner wall.
Oil-free operation by absence of flowable lubricant to avoid silicone-oil particle/protein degradation and immune-response risks for biologics.
Very low and consistent breakout and glide forces reported without flowable lubricant.
High-altitude vacuum stability exceeding ASTM requirements reported.
Provides lubricity for convertible-plunger operation.
Reduces or eliminates need for a separate flowable silicone lubricant (silicone oil).
Minimizes extractables and leaching.
Minimizes protein binding.
Protects against drug pH (about 4–10).
Maintains CCI and gas-tight sealing.
Achieves very low, consistent breakout force (Fi) and maintenance force (Fm) without flowable lubricant.
Supports stability during severe high-altitude transport testing with no observable plunger/storage-ring movement.
Documented Applications
Used in a pre-filled syringe for dispensing an injectable drug product, with operation in a storage mode and a dispensing mode using the convertible plunger disposed within the medical barrel.
Parenteral containers and medical barrel systems using a convertible plunger for operation in a storage mode and a dispensing mode, including pre-filled syringes.
Pre-filled syringe and ophthalmic syringe use cases described in connection with ophthalmic drug compatibility.
Storage mode and dispensing mode operation in a convertible plunger disposed within a medical barrel containing an injectable drug product.
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