MANIFOLD

Abstract: A manifold for a syringe designed for concomittant injection of two different medicines from two cylinder ampoules (2) comprises a body (5) manufactured from a plastic compatible with the medicines. Two needles (9) are embedded in the body (5) each having a pointed end projecting from the rear side of the body (5) with a spacing corresponding to the spacing of the piercable closures (3) of the two cylinder ampoules (2). The other ends of the needles (9) open into a mixing chamber (6) from which an injection needle (11) projects through the front side of the body (5). The injection needle (11) is mounted in a needle hub (12) screwed onto a thread surrounding the mixing chamber (6) at the front side of the body (5) and the injection needle passes through a rubber membrane (7) sealing the mixing chamber (6). Alternatively, the injection needle may be embedded in the body (5).

Description: MANIFOLD The invention relates to an apparatus for simultaneous injection of two different kinds of preparations in a preset proportion. It is known to use insulin preparations for treating diabetes. Originally 5 such preparations were quick acting and had to be injected with short time intervals. To avoid the inconvenience by such frequent injections, a preparation with a prolonged action was provided. The injection procedure has been eased by the provision of pen-shaped syringes allowing the patients to easily inject themselves with doses which may easily be set by the patient immediately before the injection 0 and this way be adapted to the patient's immediate need. By using insulin preparations having a prolonged action the number of injections a day may be minimized. However, an injection with a quick-acting preparation is necessary before a meal. To minimize the numbers of injections a mixture of the two sorts of s preparations is injected before the meal, this mixture containing the amount of quick- acting preparation to cover the need induced by the meal and the amount of preparation with prolonged action to cover the basal need until the time for the next injection. The patient may mix his insulin himself by sucking the wanted doses of the two different types of preparations from two different vials into a syringe. If he wants 0 to use a pen syringe, he has to use in his pen a cartridge with a pre-mixed mixture of the two types in a ratio which has to be chosen once for each filling of the pen. As it is wanted to vary the mixture ratio throughout the day, a pen- shaped syringe is wished for, which syringe may be adapted to two ampoules containing a quick-acting preparation and a preparation with prolonged action, 5 respectively. The pen syringe should futher be equipped with setting means for setting a dose composed of an arbitrarily set dose of one of the preparations and another arbitrarily set dose of the other preparation, and the composed dose should be injectable by one single injection. Pen-shaped syringes for injecting set doses from a single ampoule o being known, the provision of a two-barrelled pen syringe seems to be only a question of arranging two such syringes parallel with each other and providing a yoke connecting the two injection buttons of the two syringes, so that these buttons may be pressed simultaneously. However, also the needles of the two syringes should be unified in a single needle, and furthermore the volume of the flow path after the point of union should be as small as possible as this path will by each new injection contain a mixture having the ratio of the preceding injection. A manifold may be molded from a plastic material, which manifold has two pointed needles, each penetrating the rubber closure of the respective cartridges, and ducts leading from the needles to a unifying chamber which may be closed by a rubber membrane. A hypodermic needle which is pointed at both ends may be screwed onto the manifold so that one end pierces the rubber membrane and the other may be used for injecting the usual way. The plastic material used for the molding must be chosen to allow the use of very thin thread-shaped cores for the ducts, and the plastic materials known as being compatible with the medicine cannot be used for this kind of molding. Consequently it is the object of the invention to provide a manifold for a two-barrel pen syringe, which manifold is compatible with the medicine and has a very small dead space in which a mixture having one mixing ratio is transferred from one injection to the succeeding one which may be intended to have another mixing ratio. This is obtained by a manifold which according to the invention comprises a molded plastic body, a pair of needles each having a sharp end designed for piercing a rubber membrane of a cartridge, the needles being embedded in the plastic and so shaped that their sharp ends project from one side of the body with a spacing bringing them in a position to pierce the rubber membranes of the cartidges in the syringe when the manifold is mounted thereon, and the other ends of the needles opening into a mixing chamber from which a third needle leads to the outside of the body projecting from the opposite side thereof and ending in a sharp point. Hereby a manifold is obtained which could be molded with a very high precision allowing the mixing chamber to be minimized. The mixing chamber may be formed by the meeting ends of the three needles matching together, whereby the chamber is reduced to a mixing point from which the two needle tubes leading from the two cartridges continue in a common third tube forming the injection needle. The needles being embedded in the plastic material of the body are sealingly held in position without any need for welding or soldering the meeting needle ends together. The mixing chamber may alternatively be provided as a cavity in the plastic body, into which cavity the three needles open. The plastic body in which the needles are sealingly embedded makes the manifold appear as a disposable unit by which all three needles are cahnged at the same time. In another embodiment of the invention the two needles connected to the cartridges open into the cavity at one end thereof, the other end of this cavity being closed by a rubber membrane through which the third needle opens into the cavity. By this embodiment the body may be provided with a thread for receiving a hub with a double pointed needle so that one end of this needle pierces the membrane which closes the cavity. This way a manifold is provided by which the injection needle may be changed without changing the needles connected to the cartridges. The thread may likewise be so accurately provided that the one end of the needle just penetrates the membrane, allowing the depth of the mixing chamber to be minimized. As the diameter of the chamber is kept very small, it is appropriate to design the holder for the membrane covering the cavity as a needle guide having a diameter corresponding to the diameter of the chamber. In the following the invention is described in further details referring to the drawing, in which Figure 1 shows schematically a sectional view of an end part of a two- barrel pen syringe with a manifold having a mixing chamber appearing as a cavity in the body, and Figure 2 shows a view as in Figure 1 with a manifold having the mixing chamber minimized to a mixing point. In Figure 1 the housing of a pen syringe has a wall 1 surrounding two medicine cartridges 2 each being at its front end closed by a rubber membrane 3. At their rear ends the cartridges are closed by pistons 4 which are influenced by the dosing mechanism to press out optional doses from each cartridge. A manifold comprises a molded plastic body 5 having at its front end a mixing chamber 6 being forwardly closed by a rubber membrane 7 secured by a needle guide 8 pressed, bonded, or welded into the body. Two needles 9 are s embedded in the plastic body leading from the mixing chamber 6 to the outside of the body from the rear side of which they project having at their projecting ends sharp points spaced by a distance corresponding to the distance between the centres of the rubber membranes 3 of the cartridges 2 in the syringe housing. At its rear end the manifold is provided with a snap lock 10 by which the manifold is secured to the housing with the sharp ends of the needles 9 passed through the rubber membranes 3 of the cartridges 2. The needles 9 are shown leading to the bottom of the mixing chamber, the base area of which may be made even smaller than the total area of the two neighbouring ends of the needles 9 as only the openings of the needles have to be free. The needles could also lead through the side walls of the mixing chamber, the base area of which is then only limited by the fact that an injection needle 11 should be allowed to be received in the chamber. The injection needle 11 is of the well known type being pointed at both ends and being mounted in a hub 12 having an internally threaded ring 13 which may be screwed onto an external thread on the part of the body 5 surrounding the mixing chamber 6, the membrane 7, and the needle guide 8. The needle guide 8 which secures the membrane 7 in the body 5 has a central bore 14 the same size as the base of the mixing chamber 6 and placed opposite this chamber to ensure that the injection needle when passed throug the needle guide 8 will pass into the interior of the chamber 6. In Figure 2 the same reference numbers are used for the same parts as in Figure 1. The meeting ends of the needles 9 connected to the cartridges 2 are cut to form a V in which a correspondingly cut end of the injection needle 11 is received all three needles being embedded in the plastic body whereby leaks between meeting end faces are sealed by the plastic which is compatible with the medicine.

Claims: CLAIMS 1. Manifold for a two-barrel pen syringe having two parallel cartridges for two different kinds of medicine, characterized in that it comprises a molded plastic body, a pair of needles each having a sharp end designed for piercing a rubber membrane of a cartridge, the needles being embedded in the plastic and so shaped that their sharp ends project from one side of the body with a spacing bringing them in a position to pierce the rubber membranes of the cartidges in the syringe when the manifold is mounted thereon, and the other ends of the needles opening into a mixing chamber from which a third needle leads to the outside of the body projecting from the opposite side thereof and ending in a sharp point. 2. Manifold according to claim 1, characterized in that the mixing chamber is formed by the meeting ends of the three needles matching together. 3. Manifold according to claim 1, characterized in that the mixing chamber is provided as a cavity in the plastic body. 4. Manifold according to claim 3, characterized in that the two needles connected to the cartridges open into the cavity at one end thereof, the other end of the cavity being closed by a rubber membrane through which the third needle opens into the cavity. 5. Manifold according to claim 4, characterized in that the body is provided with a thread for receiving a hub with a doubble pointed needle so that one end of this needle pierces the membrane closing the cavity. 6. Manifold according to claim 4 or 5, characterized in that the membrane is fixed over the cavity by a needle guide having an opening corresponding to the opening of the mixing chamber.

Inventors: REX JOERN, REX, JOERN
Applicants: NOVONORDISK AS, NOVO NORDISK A/S
Application year: 1992
Main classification: A61M5
IPC codes: A61M5