AU2012100123A4 - Mixing device - Google Patents

Description

1 MIXING DEVICE TECHNICAL FIELD 5 The present invention relates to mixing devices and in particular to devices for mixing medications. BACKGROUND 10 Some pharmacies are compounding pharmacies that can produce customised medication on site. This is typically done when a medication that comprises a mixture of pharmaceutical substances is not readily available in a pre-packaged form from a medication supplier, particularly when the proportions of the various substances in the medication needs to be varied to suit individual patients. Examples of medications made by mixing pharmaceutical is substances includes creams, transdermal oral medications, discontinued medications, and low dosage medications. Traditionally a compounding pharmacist uses a mortar and pestle to mix medications. This is a very time consuming process and all of the equipment used must be carefully cleaned and put 20 away after use. Motorised or automated devices for mixing medications are known, but these devices are typically expensive and the cost of buying such a device often cannot be justified unless the pharmacy is mixing larger numbers of medications. US Patent 5,397,178 (Konietzko) discloses a motorised mixing device having a pedestal 25 mounted motor that is raised and lowered by a hand lever. This device mixes the medication directly in special containers that can be given to the patient and have a plunger to dispense the medication. It has a motor that drives a shaft that passes through an opening in the lid of the special containers to rotate a mixing blade positioned inside the container. 30 A later development of the device shown in US Patent 5,397,178 is the UnguatorTM "Electro Mortar & Pestle" manufactured by GAKO International AG. The Unguator TM has a motor that drives a shaft to mix medications directly in special containers that are similar to those shown in US Patent 5,397,178. The UnguatorTM is constructed in a pedestal arrangement and it has a 2 motorised linear axis that oscillates the container up and down during mixing. The operation of the UnguatorTM is automated and programmable. A disadvantage of the device disclosed in US Patent 5,397,178 and the UnguatorTM for 5 pharmacies only needing to occasionally mix a medication is the cost of purchasing and maintaining these devices. Also, the pedestal construction of these devices occupies considerable bench space and limits their portability. As such, a pharmacist only occasionally needing to mix a medication may be unable to justify buying such a device and may still use a mortar and pestle. 10 The present invention seeks to overcome at least one of the disadvantages of the prior art. SUMMARY OF INVENTION 1 In a first aspect, the present invention consists of a device for mixing medications in a container, the device comprising a housing that the container attaches to, a drive unit movable relative to the housing, and a shaft driven by the drive unit that extends through an opening in the container for rotating a mixing attachment positioned inside the container and attached to the shaft, wherein a bias means biases the drive unit away from the container, and in use a user 20 holds the housing and manually reciprocates the mixing attachment as it is rotated by the drive unit by pushing the drive unit towards the container and allowing the bias means to return it. Preferably, the drive unit is at least partially disposed within the housing and guided for movement by the housing, and the housing has a bore that the drive unit slides in. 25 Preferably, the drive unit comprises an electric motor. Preferably, the bias means comprises a spring. 30 In a second aspect, the present invention consists of a device for mixing medications in a container including a screw-cap with a closable opening thereon, said device comprises an elongate housing and a drive unit with an extending drive shaft and a removable stirrer mountable to a free end thereof, said elongate housing shares a common central longitudinal 3 axis with said drive unit and said drive shaft, said elongate housing having a first end adapted to receive and engage with said container at said screw-cap, said drive unit disposed at a second end of said elongate housing opposed to said first end and at least partially extends within said elongate housing and is telescopically movable relative to said elongate housing, 5 said drive shaft passing through said closable opening in said screw-cap such that said stirrer is positioned inside said container, wherein a bias means biases the drive unit away from the container, wherein in use a user holds said elongate housing and manually reciprocates the stirrer along said central longitudinal axis as it is rotated by said drive unit, said manual reciprocation achieved by said user periodically pushing said drive unit towards the container 10 and allowing said bias means to return it. BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is an elevation view of a preferred embodiment of a mixing device in accordance with is the present invention with a container attached thereto. Fig. 2 is a longitudinal sectional view of the mixing device shown in Fig. 1 with its drive unit in its normal raised position. 20 Fig. 3 is a longitudinal sectional view of the mixing device shown in Fig. 1 with its drive unit pushed down during mixing. DESCRIPTION OF PREFERRED EMBODIMENTS 25 Figs. 1 to 3 depict a preferred embodiment of a mixing device 1 in accordance with the present invention. Mixing device 1 comprises a housing 2 and a drive unit 7. Housing 2 is elongate and axisymmetric about a central longitudinal axis 8. It has a cylindrical body 3 open at its upper end and a flange 4 at its opposed lower end. Drive unit 7 is disposed at the upper end of housing 2, and partially extends within it. Drive unit 7 comprises an electric motor 9 and a 30 motor carrier 10 that supports motor 9. Drive unit 7 shares axis 8 with housing 2 such that they have a common axis and are coaxial with each other. Drive unit 7 is movable along axis 8 relative to housing 2 telescopically by means of motor carrier 10 sliding in a cylindrical bore 11 in housing 2 to guide the movement of drive unit 7.

4 Drive unit 7 is partially disposed within housing 2 with the upper portion of drive unit 7 protruding from the upper end of housing 2. In this embodiment, in the normal raised position shown in Figs. 1 and 2, approximately the top third to top half of drive unit 7 protrudes from 5 housing 2. Motor 9 has a rotating output shaft 12 that protrudes from its lower end. A drive shaft 13 is rigidly attached to the end of output shaft 12 by a coupling 14 such that drive shaft 13 is driven to rotate about axis 8 by drive unit 7. Drive shaft 13 extends through a threaded hole 15 in 10 flange 4 at the lower end of housing 2. A container 5 is temporarily attached to the lower end of housing 2 for the purpose of mixing a medication 6 contained within it. Container 5 has a screw-cap 16 which screws on to the body 17 of container 5. Screw-cap 16 has a threaded male boss 18 with a central opening 20 through 15 it. Container 5 is temporarily attached to housing 2 by screwing threaded male boss 18 into threaded hole 15 in flange 4. Housing 2 thereby is adapted to receive and engage with container 5. In this particular embodiment, container 5 may be given to the patient with medication 6 remaining in it after mixing, and a plunger 19 inside container 5 can be pushed to dispense medication out through opening 20. After medication 6 is mixed and container 5 is 20 detached from housing 2, a cap (not shown) is screwed on to male boss 18 of screw-cap 16 to close opening 20 and seal container 5. A mixing attachment, namely stirrer 21, is removably attached (mounted) to the free end of drive shaft 13 such that it is rotated by drive unit 7. Stirrer 21 may be shaped like an impeller. 25 Drive shaft 13 extends through opening 20 in container 5 such that its free end and stirrer 21 attached thereto are positioned inside container 5. To attach container 5 to housing 2, stirrer 21 is removed from shaft 13, and screw-cap 16 is removed from the body 17 of container 5. Screw-cap 16 is then screwed into threaded hole 15 with shaft 13 passing through opening 20. Stirrer 21 is then attached to the free end of shaft 13, and then the body 17 of container 5, 30 filled with medication 6 to be mixed, is screwed into screw-cap 16. Screw-cap 16 has a seal 25 in opening 20 to seal around drive shaft 13 to prevent medication 6 from entering into housing 2.

5 A bias means, namely coil spring 22, located within the bore 11 of housing 2, pushes on the bottom of motor carrier 10 to bias drive unit 7 away from container 5. A cap 23 is screwed onto the upper end of the cylindrical body 3 of housing 2 to retain drive unit 7 within housing 2 by means of the upper end of motor carrier 10 abutting cap 23. 5 The operation of mixing device 1 will now be described. Container 5 containing a medication 6 to be mixed is firstly attached to housing 2 with stirrer 21 within container 5, as described above. In this position, stirrer 21 is near the top of container 5, as shown in Fig. 2. Mixing device 1 with container 5 attached is then placed upright on a horizontal surface 24, such as a 10 bench top. A user holds housing 2 to support mixing device 1 by grasping cylindrical body 3 with one hand. Motor 9 is then switched on to start stirrer 21 rotating. The user then manually reciprocates stirrer 21 up and down within container 5 by repeatedly using their other hand to push down on the top of motor 9, and hence push down drive unit 7 towards container 5 along axis 8, to a position as shown in Fig. 3 in which stirrer 21 is near the bottom of container 5, 15 then allowing spring 22 to return drive unit 7 upwards to the position shown in Fig. 2. The action of stirrer 21 reciprocating whilst rotating fully mixes medication 6. After mixing, container 5 is detached from housing 2 using the reverse of the procedure to attach it. Using mixing device 1 to mix a medication is significantly easier and quicker than using a 20 traditional mortar and pestle. Also, there is significantly less cleaning required afterwards because the medication is typically supplied to the patient in the container 5 that it is mixed in. Mixing device 1 also has significant advantages over prior art motorised devices such as TM disclosed in US Patent 5,397,178 and the Unguator . Mixing device 1 is significantly more compact and portable than these prior art pedestal arrangements, and the manually operated 25 reciprocation of mixing device 1 means that it costs significantly less than these prior art devices. As such, mixing device 1 is well suited to use by compounding pharmacists who only mix medication occasionally and cannot justify the cost and bench space occupied by a device TM like the Unguator 30 Mixing device 1 may be used with various sized containers, but it is particularly suited to smaller containers that would typically be used by a pharmacist only occasionally mixing medications.

6 In other not shown embodiments of the invention, various electric motors or drive unit arrangements can be used. For example, electric motor 9 can be a hand held rotary tool, such as a DremelTM rotary tool. Also, the motor carrier may completely, or nearly completely, encase the motor. Alternatively, the casing of the motor may slide directly in the housing 2 5 such that a separate motor carrier 10 is not required. In this case, the drive unit comprises the motor only. Also, the motor may be mains powered or be powered by rechargeable batteries. In other not shown embodiments of the invention, the drive unit may be nearly fully disposed within the housing 2, with only enough of drive unit protruding to enable sufficient travel 10 when it is pushed down to enable reciprocation of the stirrer. Furthermore, the drive unit may have a pad or the like attached to its top to make it more comfortable for a user to push it down during use. In other not shown embodiments of the invention the drive shaft that the stirrer attaches to 15 may be an elongated output shaft from the motor rather than an additional shaft coupled to the motor, in which case the coupling 14 is not required. Alternatively, the motor may have a chuck to grip the drive shaft, rather than output shaft 12 and coupling 14. In the embodiment described above, the stirrer 21 detaches from the drive shaft 13. However, 20 in other not shown embodiments of the invention the stirrer (mixing attachment) may have an integral drive shaft that is pushed through the opening in the screw-cap of the container to couple with a chuck driven by the drive unit. Also, various shapes of mixing attachments may be used, ranging from a simple bar to a complex shaped impeller. 25 In other not shown embodiments of the invention, a stop may be built into the bore 11 of housing 2 to limit the downward travel of drive unit 7. This stop would therefore prevent stirrer 21 from contacting the bottom of container 5, and the stop could be adjustable for different size containers. 30 In other not shown embodiments of the invention, bias means other than a coil spring may be used. For example, the bias means may comprise a tube made from an elastomer, such as rubber.

7 The terms "comprising" and "including" (and their grammatical variations) as used herein are used in an inclusive sense and not in the exclusive sense of "consisting only of'.

Claims (5)

1. A device for mixing medications in a container, the device comprising a housing that the container attaches to, a drive unit movable relative to the housing, and a shaft driven by the 5 drive unit that extends through an opening in the container for rotating a mixing attachment positioned inside the container and attached to the shaft, wherein a bias means biases the drive unit away from the container, and in use a user holds the housing and manually reciprocates the mixing attachment as it is rotated by the drive unit by pushing the drive unit towards the container and allowing the bias means to return it. 10

2. A device for mixing medications as claimed in 1, wherein the drive unit is at least partially disposed within the housing and guided for movement by the housing, and the housing has a bore that the drive unit slides in. is

3. A device for mixing medications as claimed in claims 1 or claim 2, wherein the drive unit comprises an electric motor.

4. device for mixing medications as claimed in any of claims I to 3, wherein the bias means is a spring. 20

5. A device for mixing medications in a container including a screw-cap with a closable opening thereon, said device comprises an elongate housing and a drive unit with an extending drive shaft and a removable stirrer mountable to a free end thereof, said elongate housing shares a common central longitudinal axis with said drive unit and said drive 25 shaft, said elongate housing having a first end adapted to receive and engage with said container at said screw-cap, said drive unit disposed at a second end of said elongate housing opposed to said first end and at least partially extends within said elongate housing and is telescopically movable relative to said elongate housing, said drive shaft passing through said closable opening in said screw-cap such that said stirrer is positioned 30 inside said container, wherein a bias means biases the drive unit away from the container, wherein in use a user holds said elongate housing and manually reciprocates the stirrer along said central longitudinal axis as it is rotated by said drive unit, said manual reciprocation achieved by said user periodically pushing said drive unit towards the container and allowing said bias means to return it.