Self-metering cartridge

Details Self-metering cartridge Self-metering cartridge

1999-07-12

2001-04-10

Kennedy, Sharon (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

Reexamination Certificate

active

06213984

ABSTRACT:

BACKGROUND
1. Field of Invention
This invention relates to multidose, medical injection syringes used for the vaccination and treatment of livestock diseases. More specifically, it relates to a process and a closed handling and delivery system for those injectable animal health products used in syringes and how the dosage level administered to the patient is controlled or metered.
2. Description of Prior Art
Generally speaking, in multidose, pistol grip livestock syringes, the precise metering of the dosage dispensed is accomplished by restricting the stroke of the plunger rod. Heretofore, the stroke of the plunger rod has been controlled by mechanical systems incorporated into the syringe body and trigger mechanisms. Original designs of pistol grip syringes commonly include ratchet and pawl mechanisms, wherein the trigger is squeezed and a pawl attached to the trigger engages a ratchet, formed on the plunger rod. The plunger rod is then advanced forward to dispense the medicament from the barrel of the syringe.
Metering is accomplished by an adjustable stop attached to either the trigger, as is demonstrated in U.S. Pat. No. 3,110,310 to Cislak (1963), or to the syringe body as is shown in U.S. Pat. 4,014,331 to Head (1977). The adjustable stop restricts the forward movement or stroke of the plunger rod, therefore metering the amount of medicament dispensed. Similar mechanisms for dosage metering are employed when pre-filled cartridges are used with pistol grip syringe bodies as is shown in U.S. Pat. No. 4,738,664 to Prindle (1988) and U.S. Pat. No. 3,517,668 to Brickson (1967).
Phillips et al. (1988), in U.S. controlled by a threaded adjustment on the anterior end of the syringe body. Other known cartridge type systems generally utilize a single dose system wherein one full squeeze of the trigger dispenses the entire contents of the cartridge as is shown in U.S. Pat. No. 4,576,591 to Kaye et al. (1986) and U.S. Pat. No. 4,968,303 to Clarke et al. (1990).
With those methods of dosage metering, the amount of medicament dispensed from a multi-dose cartridge is determined by a setting or an adjustment made to the syringe or applicator by the technician. Mechanical dosage settings are often bumped or may slip to the next setting so that many animals may be injected with the improper dosage before the mistake has been detected and the correction is made. It is also not uncommon for the technician to accidentally set the dosage adjustment to an improper setting. Most medicaments have a prescribed dosage level, which technically could eliminate the need for dosage adjustment by the technician.
There has not heretofore been provided a self-metering cartridge system or a system for automatically metering a predetermined dosage of a medicament from a cartridge.
SUMMARY OF THE PRESENT INVENTION
Dosage levels for most medicaments, particularly vaccines, are constant and prescribed by the manufacturer of the vaccine. As an example, a vaccine for the prevention of X disease may require a 5 milliliter dose while a different vaccine for Y disease may prescribe a 2 milliliter dose. In our self-metering cartridge system, all syringe bodies are capable of dispensing any dosage level up to the largest dosage that may be prescribed. The self-metering cartridge will dictate the length of the stroke of the plunger rod therefore dictating the dosage level of the medicament dispensed with each squeeze of the trigger.
In practice, a 2-milliliter dose product will be packaged in a self-metering cartridge that will restrict the forward movement of the plunger rod and allow precisely 2 milliliters of medicament to be dispensed from the cartridge. Similarly a 5-milliliter dose self-metered cartridge will stop the forward movement of the plunger rod when 5 milliliters of medicament have been dispensed from the cartridge. If the loaded cartridge in the chamber is not equipped with the self-metering aspect, a full squeeze of the trigger will allow the plunger rod to advance as far forward as is mechanically possible. That full squeeze will dictate the largest dosage that the syringe is capable of administering. As an example, an unrestricted full squeeze may dispense 10 milliliters of medicament.
The advantage to the self-metering cartridge is that no human error or mechanical malfunction of an adjustable metering mechanism can cause the syringe to give an improper dosage. Even if the wrong medicament has been accidentally loaded into the syringe, the proper dosage for that particular medicament will be given. In addition, the stop mechanism for metering the dosage level has bene simplified to no adjustable or moving parts. When a cartridge is loaded into the barrel of a syringe body, the metering is automatic and specific to the product contained in the cartridge.
Other features and advantages of the present invention will be apparent from the following detailed description and the accompanying drawings.


REFERENCES:
patent: 5190191 (1993-03-01), Reyman
patent: 5733258 (1998-03-01), Lane
patent: 5759171 (1998-06-01), Coelho et al.
patent: 5964736 (1999-10-01), Lane

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