Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1991-08-28
1993-08-03
Rosenbaum, C. Fred
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604211, 604218, 604232, A61M 500
Patent
active
052324591
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a pre-filled multi-dose syringe for example for the administration by injection of a drug or other pharmaceutical product. It may take various forms; for example it may be generally in the shape of a fountain-pen, or in the shape of a conventional syringe,
BACKGROUND OF THE INVENTION
The invention particularly relates to such a syringe which is constructed relatively inexpensively and is therefore intended to be discarded when the product with which it has been filled has been exhausted.
Conventional disposable syringes contain only a single dose of the drug concerned, but in certain cases multi-dose syringes are advantageous, especially where a patient has to administer doses of the drug himself over a period of time, possibly at a frequency of more than one dose per day. In such a case the total daily dose, or even the total dose for more than one day, could be contained in a single disposable syringe to be administered in stages as required.
One multi-dose syringe is described in W088/07874. It includes a housing for a phial of liquid to be injected, having adjustment means for the dose incorporating a stop to limit the stroke of a plunger for forcing the injectable liquid out of the phial through a needle. The position of the stop is variable by rotation of the adjustment means. Ratchets are provided to ensure that the adjustment means can be rotated only in one direction and that the plunger can be displaced only in one direction. A protective cap is provided for the needle and this can be removed and fitted to the opposite end of the syringe so that an indicator line on the cap can be used as a guide to assist in a zeroing dose measuring scale associated with the adjustment means. Injection is accomplished by pressing on the cap when fitted to the end of the syringe opposite the needle.
This syringe suffers from several disadvantages. Firstly, the protective cap must be removed from the needle before the dose can be set. The needle is susceptible to damage at this time and it would be preferable to be able to set the dose with the cap still fitted over the needle and thus protecting it. Also, it is difficult to carry out injection with the cap still fitted over the end opposite needle but any attempt to remove the cap prior to injection is likely to cause undesired premature discharge of liquid through the needle. Furthermore, the ratchet mechanisms employed in W088/07874 require great precision in manufacture and in practice are likely to be the source of imprecise dosing.
SUMMARY OF THE INVENTION
The multi-dose syringe of this invention is relatively simple in construction and does not involve potentially unreliable ratchet mechanisms. It incorporates an in-built dosing ring to assist in metering the dose to be injected and does not require premature removal of the protective cap for the needle.
According to this invention a pre-filled syringe comprises a phial containing a measured quantity of an injectable product, a fixed wall at one end of the phial to receive a needle, a displaceable wall at the opposite end of the phial and displaceable into the phial by means of a plunger to expel the product out of the phial through the needle, and a two-part housing for the phial and plunger in which the two parts are connected by interengaging screw threads and having a stop surface on one housing part co-operable with a corresponding surface on the plunger to limit displacement of the plunger into the phial, wherein the position relative to the phial of the stop surface can be varied by rotating the two housing parts relative to one another, thus controlling the distance by which the plunger can be displaced into the phial, characterised by a graduated dosing ring mounted coaxial with, adjacent to, and rotatable relative to both housing parts.
Preferably, the first housing part holds the phial and the second housing part incorporates the said stop surface, so that relative rotation of the two housing parts enables the position of the stop surface to
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Kabi Pharmacia AB
Polutta Mark O.
Rosenbaum C. Fred
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