Automatic injector with anti-coring needle

Inventors

Wilmot, John G. • Whittier, John • Hill, Robert L. • Cain, Seth P. • Mesa, C. Michael

Assignees

Meridian Medical Technologies Inc

Abstract

In one embodiment, an automatic injector comprises a cartridge adapted to contain a charge of medicament, a seal structure disposed toward a forward end of the cartridge, a plunger normally disposed in a generally rearward end of the cartridge and movable through the cartridge toward a generally forward end thereof in response to an actuating procedure. The movable plunger rearwardly confines the medicament within the cartridge. A needle normally disposed in communication with the medicament container provides a passage in which the medicament is released into an individual's flesh in response to an actuating procedure projecting the needle into the flesh of the individual. The cartridge having an increased friction region so as to slow the motion of the plunger when the forward end of the needle travels through the seal in order to eliminate coring.

Core Innovation

The invention relates to an automatic injector that includes a medicament cartridge, a seal structure disposed toward a forward end of a housing, and a needle projectable from the forward end of the housing through the seal structure. A charge of medicament contained in the cartridge is confined by a movable plunger that is normally disposed in a generally rearward end of the cartridge and is movable through the cartridge toward a generally forward end thereof in response to a predetermined actuating procedure. The movement of the plunger forces the medicament through the needle and into the flesh of an individual, while a releasable energy source projects the needle and slidingly drives the plunger through the cartridge in sealed relation.

A key aspect of the invention is that the needle is defined as a hollow rigid tubing having a cylindrical wall and a lumen opening or longitudinal passage. The needle includes a forward pointed portion comprising a lancet shaped tip or a forward end tip, with the tip bent in a curve and structured to shield the entire cross section of the lumen opening or longitudinal passage cross section perpendicular to the longitudinal axis. The tip includes primary and secondary facets, with the secondary facets ground at an angle at the inner surface of the needle, and further includes an angle-defined bend geometry in which the forward tip portion is bent at an angle approximately between 51 degrees and 100 degrees.

The disclosed anti-coring concept addresses coring associated with needle piercing of the seal structure by modifying the cartridge/plunger interaction to reduce needle speed while piercing the seal. An increased friction region in the cartridge/plunger interaction includes a narrowed diameter portion or a corrugated friction region that slows plunger/needle acceleration so that needle speed while piercing the seal is kept below about 680 inches/s and preferably kept above about 150 inches/s. Documented test results in the disclosure indicate reduced coring frequency and smaller core particle size when the increased friction region is provided.

Additional anti-coring needle/tip configurations and damping mechanisms are also disclosed in the document. The needle tip geometry includes a curved C-tip shielding the lumen, and the disclosure further references different tip forms and needle wall effects. An optional anti-coring conformal coating material is disclosed as Parylene or polyparaxylylene on the needle tip, including an indicated coating thickness range, and an alternative damping mechanism is described using a damping disk that reduces needle acceleration through viscous flow resistance.

Claims Coverage

The document includes three independent claims, each covering an automatic injector with a housing, a seal structure toward a forward end, a medicament cartridge, a movable plunger, and a projectable needle driven by a releasable energy source to expel medicament into flesh in response to a predetermined actuating procedure. Across these independent claims, the main inventive features focus on needle tip geometry that shields the lumen cross section and, in at least one claim, quantitative bending-angle definition; additional dependent claim coverage specifies polyparaxylylene coating on the needle tip and a defined coating thickness range.

Across the independent claim set, the core claim coverage centers on an automatic injector with a seal structure and a projectable needle driven through a medicament cartridge by a movable plunger and a releasable energy source, where the needle includes a bent tip that shields the lumen or longitudinal passage cross section. Additional inventive features supported by the dependent claim set include polyparaxylylene coating on the needle tip and a defined polyparaxylylene coating thickness range, as well as a defined forward tip bend angle between 51 degrees and 100 degrees.

Stated Advantages

Documented Applications