DE3515624A1 - Medicament metering device having a main store and a metering chamber - Google Patents

Abstract

A metering device has a main store (1) and a metering chamber (3) for a medicament (5). The volume of the metering chamber (3) is chosen such that it is in the middle range between the volume of the main store (1) and the volume of the lowest dose of the medicament (5) predetermined for administration. A metering drive (25;29;50) is arranged such that it only acts upon the medicament (5) present in the metering chamber (3) during the metering process. Once the metering chamber (3) is empty it is filled up from the main store (1). The advantage of the arrangement is that disturbances due to administration, e.g. changes in temperature or environmental pressure, affect the metering process in the metering chamber (3), but not in the main store (1), only with regard to the medicament volume. <IMAGE>

Description

Drug dosing device with-a-main memory and

a metering chamber The invention relates to a metering device with a Main memory and a dosing chamber for a drug, with a control unit, the expulsion of the drug located in the dosing chamber by a Outlet line controls, with an outlet valve in the outlet line and with one Connection line between the main memory and the dosing chamber.

In the field of medicament dosing devices, in particular for implantable ones Devices, the following requirements should be well met: a) Those with the drug Parts that come into contact should be as little as possible mechanically with this during operation interact so as not to unnecessarily damage the drug, i.e. e.g. B. that that Medication should be squeezed as little as possible or should be tumbled during the pumping process; b) very small volumes (approx. 1 pl) should be able to be dosed precisely in terms of time; c) the device should be insensitive to application-related interference, such as z. B. Temperature changes, forces and pressure, gas bubbles in the drug tract, or the like; d) the components for the device should be miniaturized; and e) the dosing drive of the dosing device should have a low energy consumption.

There are currently no fully satisfactory requirements for the above-mentioned requirements Solution: A. With common dosing devices that contain a roller pump as a dosing drive, conditions b) and c) are well met. However, the conditions must a), d) and e) compromises are made.

B. For valve pumps with a small pump stroke (approx. 1 Pl) is so far unsatisfactory that they are disabled by very small gas bubbles. The reason for this is that the dead volume between the valves from constructive Reasons cannot be made small compared to the stroke volume. The compression is so bad that when gas is filled in the valve tract, the opening pressure of the valves does not is achieved.

C. There are also suggestions in which the metering drive is on the whole Storage volume (approximately 10 ml) acts. The disadvantage here is that unavoidable Changes in temperature or pressure, volume shifts occur, so that the above conditions b) and c) cannot be fulfilled. Compensation and shielding measures are theoretically conceivable, but especially for those that apply to implantable devices Boundary conditions such as B. Condition d), not feasible.

D. Dosing devices, in which the drug by the vapor pressure of a easily evaporated substance is expelled are mainly because of their hitherto not sufficiently controllable security risks uncontrollable peaceful. The drug is under constant excess pressure. Therefore, error cases like z. B. a leaky valve, lead to an uncontrolled overdose.

In the European patent 0,039,124 a dispenser is the initially described type. The dosing device contains a main memory for a drug made by a pressurized liquid under vapor pressure is applied. A connecting line leads from the main memory to a as the first flow limiter acting capillary, with which a basal rate for the Drug can be adjusted to a mixing chamber. A secondary line that lies parallel to the flow limiter and also opens into the mixing chamber a second flow limiter, a metering chamber, a controllable valve and a third flow restrictor. The dosing chamber is permanent over the second Flow limiter refilled. The medication is discharged via the controllable valve of the dosing chamber via the third flow limiter as the lower rate of the basal rate mixed in. The control of the valve turns the dosing chamber into so-called Infused bolus rates, such as those used in insulin as a drug e.g. B. someone with insulin must be consumed at meals. No measures are provided for this dosing device with which, for example, an increase in the basal rate due to a temperature-related Overpressure in the main memory can be compensated. Furthermore, there is a failure of the valve is given a continuous flow of medication in addition to the basal rate.

The present invention is based on the idea that both metering devices with extremely small pump volumes as well as dosing devices that use the entire drug store in the Funding mechanism is integrated, have major disadvantages. A mediocre at which the distance to both extreme solutions is about the same, could be preserve the specific disadvantages of the two extreme solutions.

The object of the invention is therefore to provide a metering device of the type mentioned at the beginning Art to be trained in such a way that as many of the requirements a) to e) mentioned as possible are good are fulfilled.

This object is achieved according to the invention in that in the connecting line an inlet valve is arranged that the drug in the main memory at most is under ambient pressure that the metering chamber has a volume which is im middle range between the volume of the main memory and the volume of the smallest, by the application predetermined dosage of the drug is, and that a Dosing unit is provided with a dosing drive, which is under the control of the control unit stands and acts on the metering chamber, the metering drive for suction of the drug from the main memory and for dispensing the drug into the Outlet line ensures. It is particularly advantageous if the metering unit of the metering chamber has an auxiliary pumping circuit.

By choosing the medium volume "the mentioned conditions a) to c) are essentially fulfilled equally well. When using a piston pump or A roller pump in conjunction with an auxiliary pumping circuit makes the drug special little mechanical stress. Due to the dimensioning of the piston pump, this, like the roller pump, has very small volumes (approx. 1 pl) with exact timing dose. Application-related interference, like the mentioned temperature changes or the effects of force or pressure, only develop their effect during the dosing process on the (relatively small) average volume and are therefore harmless. the The solution according to the invention does not require any further structural components apart from the second valve, to compensate for temperature fluctuations or pressure fluctuations. The individual structural components can largely be produced in miniaturized form. The metering drive only acts on the average volume.

Further advantages and configurations of the invention emerge from the following description of the figures in conjunction with the subclaims. It 1 shows a first exemplary embodiment of the invention with a piston drive, Fig. 2 shows a second embodiment of the invention with a roller pump and a Auxiliary pumping circuit, and FIG. 3 shows a third exemplary embodiment of the invention with a prestressed bellows as a metering chamber According to Figure 1 are as parts of a metering device a main memory 1 and a metering chamber 3 for a medicament 5, in particular insulin, intended. The main memory 1 is designed so that its content, the drug 5, regardless of the level to ambient pressure or a lower pressure is located. This can be implemented, for example, as a main memory 1 a pliable sack or a vessel with a weakly resilient wall is provided, is used.

The area around the dosing device is considered to be the in which the main memory 1 is installed.

It is a dosing device implanted in a patient around the pressure in the patient's body, i.e. essentially around normal pressure the atmosphere in which the person wearing the dispenser is currently located.

A connecting line 7 leads from the main memory 1 to the metering chamber 3. In the connecting line 7, an inlet valve 9 is arranged. The inlet valve 9 is preferably a check valve, which in the presence of one at the inlet valve 9 set pressure difference between the main memory 1 and the dosing chamber 3 allows a drug flow to the metering chamber 3 and in the absence of one Sufficient pressure difference, the backflow of the drug 5 into the main memory 1 prevented. As an alternative to this, the inlet valve 9 can also be an externally controllable one Valve, in particular an electrically operated miniature valve.

An outlet line 11 leads from the dosing chamber 3 to a connection part, to which a catheter 13 is connected. In the outlet line 11 is located an outlet valve 15. The outlet valve 15 is preferably also a check valve, which at a predetermined pressure difference from the metering chamber 3 to the catheter 13 allows a throughflow and which one upon reversal of the pressure direction Backflow of the medicament 5 from the catheter 13 into the metering chamber 3 is prevented.

The metering chamber 3 is formed by a housing part 17, which is closed at the end by a piston 19. The piston 19 is in both directions linearly movable, which is indicated by a double arrow, so that the volume the dosing chamber 3 is reduced and can be enlarged. Preferably the housing part 17 is formed as a hollow cylinder, and the piston 19 is at the end an optionally left and right rotating spindle 21 attached. The dimensions of the housing part 17 and the available movement distance of the piston 19 are dimensioned so that that the metering chamber 3 can assume a predetermined maximum volume. This predetermined maximum volume is in the middle range between the volume of the Main memory 1 and the volume of the lowest, predetermined by the application Dosage amount of the drug 5.

The mean volume is understood here to be the logarithmic mean. Do the volumes differ e.g. B.

by 6 powers of ten, the mean volume has "of both reference volumes the same logarithmic distance of 3 powers of ten. Is it the one Drug 5, for example insulin, is a convenient size for main memory 1 a volume of approx.

10 ml. The lowest sensible dose of insulin is with a small basal rate is required for the drug 5 and is in the supply of one average human patient at approx. 1 P1. Choosing the size of the Dosing chamber 3 corresponding to the logarithmic mean between the two volumes 10 ml and 1 μl results in a size of approx. 100 μl than for this example Desired size of the dosing chamber 3.

In another drug 5, which z. B. in greater concentration and therefore smaller, very small doses must be available, this value can be adjusted accordingly be smaller. The range of values for the size of the dosing chamber 3 and thus for the predetermined maximum volume is likely to be 5 for different drugs and main memory sizes between 10 and 1000 P1.

The metering chamber 3, the piston 19 and the spindle 21 are parts of a Dosing unit 23, which continues to have a dosing drive 25 includes. The metering drive 25 can be a common stepper motor that drives the spindle 21 Rotates choice back and forth. The metering drive 25 is activated by a control unit 27, in which, for example, the value for the basal rate plus various Retrieval programs for additional rates are stored. Control units 27 and dosing units 23 of the type mentioned are known per se in the art. The new properties of the control unit 27 are explained in more detail below.

As already mentioned, the inlet valve 9 and the outlet valve 15 check valves are preferably used. The rotates in normal dosing mode Dosing drive 25 according to the pending control program in the control unit 27 the spindle 21 forward. It thus causes the piston 19 to advance A pressure gradient builds up, which sets the specified response pressure of the outlet valve 15 overcomes and a flow of the medicament 5 in the outlet line 11 allows. From there it reaches the application site in the patient via the catheter 13. This Feed continues until the piston 19 ciii a stop (not shown) has arrived, whereby the metering chamber 3 has assumed its minimum volume. This piston position is sent to the control unit by a sensor (not shown) 27 reported, whereupon it reverses the polarity of the metering drive 25 and the spindle 21 in the opposite direction Direction is rotated. The piston 19 is moved back again, whereby in the metering chamber 3 builds up a negative pressure.

As an alternative to the stop measurement of the piston 19 by a sensor in the control unit 27, a program can also be set in such a way that after reaching of, for example, 20 revolutions of the spindle 21 of the metering drive 25 reversed and the 20 revolutions are run back in one go. A (not Device shown) for measuring the number of revolutions made in the metering drive 25, which is known in the art.

Due to the negative pressure produced when the piston 19 moves back in the metering chamber 3 there is a pressure gradient in the blocking direction at the outlet valve 15 and in the release or flow direction at the inlet valve 9. It is thereby Medication 5 from the main memory 1 into the dosing chamber 3 in relatively refilled in a short time.

If the dosing chamber 3 is filled with medicament 5 in this way, the metering drive 25 is reversed again via the control unit 27, so that further Control pulses advance the piston 19 in the direction of compression. The normal dosing operation according to the stored control program is continued until the Piston 19 again its stop or a distance corresponding to z. B. 20 spindle revolutions has covered. The cycle then repeats itself with polarity reversal and the piston moving backwards 19 and the associated refilling of the metering chamber 3 again.

The advantage of the arrangement shown is that changes in volume due to temperature or pressure fluctuations in the relatively large main memory 1 have practically no influence on the dosing behavior of the dosing device. Since the Dosing chamber 3 in volume by a factor of z. B. 100 is chosen smaller than the main memory, a negative effect is also reduced by a factor of 100. A failure of the outlet valve 15 does not inevitably result in an emptying of the Main memory 1 towards the exit end of the catheter 13 after themselves. The same applies to a failure of the inlet valve 9. Due the predetermined condition that the content of the main memory 1 is at most Ambient pressure is, if the inlet valve 9 fails, there is no driving force present, which could empty the main memory 1. So there will be a high level of security against valve failure and against temperature and pressure fluctuations and Like. Achieved. At the same time, disadvantages that would arise are avoided, if the pump stroke of the metering unit 23 were too small. The one in the exit valve 15 existing dead space is very small in relation to the volume of the dosing chamber 3. There is no possibility that an in the dead space of the outlet valve 15 Existing gas bubble simply compressed and again by the pumping stroke of the piston 19 is relaxed without the drug is promoted. These benefits all apply also for the two embodiments described below.

In FIGS. 2 and 3, the same reference numerals are used for the same components used as in Figure 1. Figure 2 shows a main memory 1, which has a Connecting line 7 is connected to a metering chamber 3. In the connecting line 7 an inlet valve 9 is arranged.

An outlet line 11 leads from the metering chamber 3 to a catheter 13. In the outlet line 11, an outlet valve 15 is arranged. These components and their function are the same as described in FIG.

In the embodiment of Figure 2, the metering chamber 3 is on one Side closed with a flexible membrane 29 instead of the piston 19. the Dosing chamber 3 is here essentially formed by a hollowed-out body, in which an inlet and outlet opening is let.

A chamber 31 adjoins the flexible membrane 29. The chamber 31 is in particular also formed by a hollowed-out body. The outer wall of the chamber 31 has an opening 33 which is connected to a connecting piece 35 is provided. A flexible hose 37, preferably a flexible hose, is attached to the connecting piece 35 Silicone hose, connected. The hose 37 is inserted into a roller pump 38. At the end of the hose 37 there is a storage container 39, which is used for storage an auxiliary liquid 41 is used. The storage container 39 can be used as a slack sack be trained. The roller pump 38 serves only as a metering drive 25 for the auxiliary liquid 41. The roller pump 38 is functionally connected to a control unit 27. The control unit 27 sends, for example, pulses to an electric stepping motor or DC motor in roller pump 38. The stepper motor has at the end of its Shaft in a known manner on a roller carrier 43 which, depending on the number of incoming pulses are rotated more or less. The direction of rotation is included reversible.

As already mentioned, the function of the main store 1 is the dosing chamber 3, the connecting line 7, the inlet valve 9, the outlet line 11 and the Outlet valve 15 is identical to the function described in FIG. 1. Instead of of the piston 19 described there, the flexible membrane 29 is arranged here. Ever according to the extent to which auxiliary liquid 41 is pumped into the chamber 31 the flexible membrane 29 is bent. It thus drives the drug 5 out of the Dosing chamber 3 into outlet line 11. Is the flexible membrane 29 ready bent so that it is located near the wall of the metering chamber 3, so rotates the control unit 27 reverses the direction of rotation of the roller pump 38 and then gives in a short time Time many control impulses to the motor of the scooter pump 38. The Pump head 43 will rotate relatively quickly and that located in chamber 31 will rotate Pump auxiliary liquid 41 back into the reservoir 39.

The flexible membrane 29 is sucked downwards, with the result has that the drug 5 is conveyed from the main memory 1 into the dosing chamber 3 until there is a predetermined maximum volume of approx. 100 μl in the dosing chamber 3 is located. This cycle is repeated until main memory 1 is emptied.

An alternative to controlling the roller pump 38 is to that according to the volume of the filled metering chamber 3, for example, 100 pump head revolutions are necessary until the flexible membrane 29 has reached its upper end position. the Control unit 27 adds the revolutions of the roller carrier 43 until they reach the specified Number has reached 100. Then the direction of rotation of the motor is reversed, and the 100 revolutions are reversed without interruption, the membrane 29 its assumes the lower end position, so that the metering chamber 3 returns to its initial filled state achieved. The control unit 27 occupies the stepper motor in normal metering mode rrlt Control signals that correspond to the delivery of the desired amount of medication. The basal rate and the infusion rate can be freely selected.

FIG. 3 again shows a main memory 1, which is connected via a connecting line 7 is connected to a metering chamber 3. In the connecting line 7 is an inlet valve 9 arranged. An outlet line 11 leads from the metering chamber 3 to a catheter 13. In the outlet line 11, an outlet valve 15 is arranged. How it works these components and their interaction has already been described in FIG.

In this embodiment, the wall of the metering chamber 3 is through an elastic bellows 50 is formed. The bellows 50 is biased so that it a medicament located in the dosing chamber 3 without the presence of a counterforce 5 through the outlet valve 15 and the off that line 11 would drive out. Of the Bellows 50 is surrounded by a cylindrical housing 52. The housing 52 has on Bottom a bore or opening to which a first line 54 is connected. The first line 54 branches out into a second line 56 and a third Line 58. In the course of the second line 56 is a pump 60 whose The conveying direction points in the direction of the arrow 62. In the course of the third line 58 is a flow-controlling element 64. It can be, for example around a controllable valve or a capillary with a controllable outlet cross-section Act. The second and third lines 56, 58 lead into a storage container 39, in which an auxiliary liquid 41 is stored.

In this embodiment, the bellows 50 is in cyclical movements pulled together and pulled apart. For contraction, the flow-controlling Element 64 actuated by the control unit 27. If the flow path is through the third line 58 released, then-caused by the pretensioning of the bellows 50 flows Auxiliary liquid 41 through the third line 58 into the interior of the housing 52 into the outer environment of the bellows 50. The bellows 50 contracts and drifts so the drug 5 out of the outlet line 11 out. This happens until the bellows 50 has reached its end position and the metering chamber 3 is almost empty. Then the pump 60 is actuated by the control unit 27, whereupon the auxiliary liquid 41 is pumped back from the interior of the housing 52 into the storage container 39. The stock container 39 is, for example, a pliable one Sack that does not oppose a change in volume. With pump operation the pump 60 creates a negative pressure on the outside of the bellows 50, which this again in his retracts the expanded form shown in FIG. At the same time the dosing chamber 3 filled with medicament 5 from the main memory 1. This is repeated here as well previously described cycle until main memory 1 is emptied.

The exemplary embodiments shown have a significant advantage on that due to temperature or Umwelteinwir effect pressure changes during Only influence the dosing chamber 3 in the dosing process. The main memory 1 is loaded with the same temperature and environmental effects, what but due to the structural design of the main memory 1 as z. B. pliable Sack shows no effects on the dosing behavior of the dosing device.

Another advantage of using an auxiliary pumping circuit is that also known dosing devices with the smallest Dos.ervolumen (1 pl) are used can be.

Since the auxiliary pumping circuit is usually a complete manufacturing process Part is that later does not have to be refilled or serviced by the user the occurrence of gas bubbles is avoided.

17 claims 3 figures List of Reference Numbers 1 Main storage 3 Dosing chamber 5 Medication 7 Connection line 9 Inlet valve 11 Outlet line 13 Catheter 15 Outlet valve 17 Housing part 19 Piston 21 Spindle 23 Dosing unit 25 Dosing drive 27 Control unit 29 flexible membrane 31 Chamber 33 Opening 35 Connection 37 Hose 38 Roller pump 39 Storage tank 41 Auxiliary liquid 43 Roller carrier 50 Bellows 52 Housing 54 1st line 56 2nd line 58 3rd line 60 Pump 62 arrow 64 Flow-controlling element

Claims (17)

Claims 1. Dosing device with a main memory and a Dosing chamber for a drug, with a control unit that controls the expulsion of the controls located in the dosing chamber medicament through an outlet line, with an outlet valve in the outlet line and with a connecting line between the main storage and the dosing chamber t that in the connecting line (7) an inlet valve (9) is arranged that the drug (5) in the main memory (1) is at most under ambient pressure that the metering chamber (3) has a volume which is between the volume of the main memory (1) and the volume of the smallest, due to the application predetermined dosage amount of the medicament (5), and that a dosage unit (23) is provided with a metering drive (25) which is under the control of the control unit (27) and thereby acts on the metering chamber (3), the metering drive (25) for a suction of the drug (5) from the main memory (1) and for one Provides delivery of the drug (5) into the outlet line (11). 2. Dosing device according to claim 1, d a d u r c h g e -k e n n z e i c h n e t, that the outlet valve (15) is a check valve that the reflux of the drug (5) to the dosing chamber (3) locks. 3. Dosing device according to claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t that the inlet valve (9) is a non-return valve that controls the reflux of the drug (5) to the main memory (1) locks. 4. Dosing device according to claim 1, d a d u r c h g e -k e n n z e i c n e t that the starting and / or the inlet valve (15, 9) is an electrically controllable valve. 5. Dosing device according to one of claims 1 to 4, d a -d u r c h g It is not noted that the drug (5) is insulin and the dosing chamber (3) holds a maximum volume in the range between 10 and 1000 pl. 6. Dosing device according to claim 5, d a d u r c h g e -k e n n z e i c It does not mean that the metering chamber (3) has a volume of approx. 100 pl. 7. Dosing device according to one of claims 1 to 6, d a -d u r c h g It is not noted that the main memory (1) has a volume of approx. 10 ml grasps. 8. Dosing device according to one of claims 1 to 7, d a -d u r c h g e k e n n n n n e i n e t that the outlet line (11) is directly connected to a catheter (13) connected. 9. Dosing device according to one of claims 1 to 8, d a -d u r c h g it is not noted that the dosing chamber (3) is a variable space, which is closed at the end by a piston (19) which is driven by the metering drive (25) movable in the sense of reducing and increasing the volume of the room is. 10. Dosing device according to claim 9, d a du r c h g e -k e n n z e i c h n e t that the space is formed by a hollow cylindrical body, and that the piston (19) at the end of a spindle (21) that rotates either left or right is attached. 11. Dosing device according to one of claims 1 to 10, d a -d u r c h it is not indicated that the Dosing chamber (3) a flexible one Has membrane (29) which adjoins a chamber (31) of an auxiliary pumping circuit, which part of the metering drive (25) is. 12. Dosing device according to claim 11, d a d u r c h g e -k e n n z e i c h n e t that the auxiliary pumping circuit is a bidirectionally drivable roller pump (38) includes. 13. Dosing device according to claim 10, d a d u r c h g e -k e n n z e i c h n e t that the metering chamber (3) is designed as a bellows (50) that is filled in State is tense. 14. Dosing device according to one of claims 1 to 13, d a d u r c h g It is noted that the control unit (24) integrates the dosing unit (23) controls that a basal rate with attached, given polling rate. 15. Dosing device according to one of claims 1 to 14, d a d u r c h g e k e n n n n z e i c h n e t that the main memory; 1) is designed so that it is at ambient pressure regardless of its level. 16. Dosing device according to one of claims 1 to 10, d a -d u r c h it is not indicated that the dosing chamber (3) is part of the dosing unit (23) is. 17. Method for operating a metering device with a main memory and a dosing chamber, d u r c h e k e n n n e i c h n e t that from the Dosing chamber both the basal rate and the additional rate is dosed.