A CYLINDER AMPOULE

Abstract: A cylinder ampoule (1) having a first end sealed by a closure through which an injection unit can communicate with a medicament in the ampoule and a second end closed by a piston (3) which can be forced into the ampoule (1) to press out a dose of a medicament stored in the ampoule between the closure and the piston (3) through said injection unit, which cylinder ampoule (1) has a not circular inner cross section and which piston (3) has a not circular cross section corresponding to the inner cross section of the ampoule (1). A piston rod (4) has a pressure foot (5) which has a cross section corresponding to the inner cross section of the ampoule (1) and is inrotateably connected to the piston rod (4).

Description: A cylinder ampouie The invention relates to cylinder ampoules having a first end sealed by a closure through which an injection unit can communicate with a medicament in the ampoule and a second end closed by a piston which can be forced into the ampoule to press out a dose of a medicament stored in the ampoule between the closure and the piston through said injection unit It shall be noticed that a cylinder is defined as a surface described when a line, the genera- trix, with a defined orientation in the space is moved along a guiding curve. What colloquially is called a cylinder is a so-called right circular cylinder, i.e. a cylinder whose guiding curve is a circle and whose generatrix is a line perpendicular to the plane of said circle. When talking about cylinder ampoules the word cylinder should be interpreted in the widest sense of the word although cylinder ampoules known so far is of the kind corresponding to the colloquial interpretation of the word cylinder. Cylinder ampoules may be designed for use in syringes which are e. g. used by diabetics for the injection of insulin. Some insulin types are suspended in a liquid and the ampoule have to be shaken, rotated and turned upside down for some time to re-establish the suspension of the insulin crystals which will form a sediment when the ampoule is not in use. In a common cylinder ampoule having a circular cross-section perpendicular to its axis rotation of the ampoule will only result in a rotation of the ampoule and its content as a whole and when the rotation of the ampoule is stopped the liquid body will continue is rotation and the outer part of the rotating liquid body will break away some of the crystals which have segregated on the inner wall of the ampoule and suspend them in the said outer part of the rotating liquid body whereas a homogeneous suspension where the concentration of crystals are equally suspended in the outer part and the part near the axis is difficult to obtain. Alternatively the ampoule may rotate without immediately drawing the liquid body with it. Also in this case a suspension of the segregated crystals in the outer part of the liquid body may be obtained when the ampoule wall moves relative to the liquid body but also in this case a homogeneous suspension is difficult to obtain. From EP 235 691 it is known to place in the ampoule one or more mixing bodies in the shape off balls made from a material having another density than has the liquid. When the ampoule is rotated the balls will run along the wall and loosen crystals sediments. However, the balls may have a grinding effect on the crystals which may then be deactivated. It is an object of the invention to provide an ampoule in which sediments can be re- suspended without the use of mixing bodies. This is obtained by an ampoule of the kind described in the opening of this application which ampoule according to the invention has a not circular inner cross section and the piston has a not circular cross section corresponding to the inner cross section of the ampoule. In known syringes the piston is pressed into the ampoule by a piston rod which acts on the piston directly or through a pressure foot, the piston rod being inrotatable but axially dis- placeable in the syringe. Many dose setting devices are based on engaging threads on the piston rod and a dose setting member, respectively, and a dose is set by rotating the dose setting member relative to the piston rod. E.g. from EP 327 910 is known a device by which doses may be set by increasing the total length of a piston rod, which abuts a piston of an ampoule in the device, and a piston rod extension which is through a thread connection coupled to the piston rod. The increase is obtained by rotating the piston rod extension relative to the piston rod by rotating a dose setting member which can be rotated relative to the housing and consequently relative to the piston rod. A connection between the dose setting member and the piston rod extension makes the piston rod extension follow the rotation of the dose setting member. By the resulting increase of the total length of the piston rod and its extension, the outer end of the piston rod extension which were previously flush with the end of the housing is passed out through the end of the housing. The projecting end of the piston rod extension is used as an injection button which can be pressed until jt again is flush with the housing. Thereby the piston is pressed into the ampoule a distance corresponding to the set increase of the total length of the piston rod and the piston rod extension. By such dose setting devices the piston rod must be secured against rotation relative to the housing of the syringe so that the rotation of the dose setting member relative to the piston rod may be performed by holding the house of the syringe and rotate the dose setting member relative to this housing an consequently relative to the piston rod. This securing of the piston rod against rotation relative to the housing is commonly obtained by using a piston rod which has a not circular cross section and which pass through a conforming guiding opening through a guiding element secured to the housing. In a cylinder ampoule according to the invention the piston has a cross-section corresponding to the inner cross-section of the ampoule and as this cross-section is not circular it is ensured that the piston cannot be rotated relative to said housing. According to the invention this requirement may be complied with by providing the piston rod with a pressure foot which has a cross section corresponding to the inner cross section of the ampoule and is inrotatably connected to the piston rod. In another embodiment the piston rod may be secured inrotatably to the piston. A cylinder ampoule according to the invention may make out a syringe housing and the piston rod may be threaded to form a part of a dose setting mechanism. In the following the invention is explained in further details with references to the drawing , in which figure 1 schematically shows a cylinder ampoule with a not circular cross section and with a piston having a corresponding not circular cross section. An ampoule 1 has a triangular cross section. At one end the ampoule is provided with a neck part with a flange 2 along which a rubber membrane may seal to close this end of the am- poule. The other end of the ampoule is closed by a piston 3 having a cross section corresponding to the inner cross section of the ampoule. The demand is that the cross section of the ampoule must be not circular. The triangular shape may only be seen as an example and in the principle any not circular cross section may have been chosen. It must be noticed that a cross section of a cylinder means a section perpendicular to the generatrixces of the cylinder. A threaded piston rod 4 acts on the piston 3 through a pressure foot 5 which may be integral with the piston rod or secured to this piston rod 4 in a way making the piston rod inrotatable relative to the pressure foot 5. The pressure foot 5 is sketched as having a cross section corresponding to the cross section of the piston 3 and the inner cross section of the ampoule 1. This way the piston rod is made inrotatable relative to the piston 3. The piston 3 is provided with a recess 6 having a triangular cross section. In this recess a piston rod provided with an end part having a corresponding triangular cross section may be inserted so that the piston rod is inrotatably secured to the piston without any intermediate pressure foot. A nut 7 is screwed onto the threaded piston rod and may be rotated relative to this piston rod 4 which is kept inrotatable by the ampoule. If the nut is originally abutting an end edge 8 of the ampoule, a dose may be set by screwing the nut 7 away from said edge 8 and the dose may be injected by pressing the piston rod 4 so far into the ampoule that the nut 7 again abuts the edge 8. This dose setting mechanism is independent of the housing the ampoule is mounted into and in fact no special housing is needed as the ampoule with the piston and the piston rod in itself may form a disposable syringe by which a number of doses may be set and injected. Only a needle receiving piece has to be provided at the neck end of the ampoule so that a needle hub with an injection needle communicating with the medicine in the ampoule may be mounted. Alternatively the described elements could be part of a more comprehensive mechanism serving the same purpose: Injection of a medicine. In the above example a cylinder ampoule with a triangular cross-section is described. The cylinder may have another polygonal cross-section, an elliptic cross-section, or a cross section showing combinations of straight lines and curves, without deviating from the scope of the invention, the only condition being that the cross-section is not circular.

Claims: Claims 1. A cylinder ampoule having a first end sealed by a closure through which an injection unit can communicate with a medicament in the ampoule and a second end closed by a piston which can be forced into the ampoule to press out a dose of a medicament stored in the ampoule between the closure and the piston through said injection unit, characterised in that the cylinder ampoule has a not circular inner cross section and the piston has a not circular cross section corresponding to the inner cross section of the ampoule. 2. A cylinder ampoule according to claim 1, characterised in that a piston rod has a pressure foot which has a cross section corresponding to the inner cross section of the ampoule and is inrotateably connected to the piston rod. 3. A cylinder ampoule according to claim 1 , characterised in that a piston rod is inrotateably secured to the piston. 4. A cylinder ampoule according to anyone of the preceding claims, characterised in that the ampoule makes out a syringe housing. 5. A cylinder ampoule according to anyone of the claims 2 to 4 characterised in that the piston rod is threaded.

Inventors: BUCH-RASMUSSEN THOMAS, JENSEN JENS MOELLER, POULSEN JENS ULRIK, BUCH-RASMUSSEN, THOMAS, JENSEN, JENS, MOELLER, POULSEN, JENS, ULRIK
Applicants: NOVONORDISK AS, NOVO NORDISK A/S
Application year: 1998
Main classification: A61M5
IPC codes: A61M5