HK1077239B - Improvements in and relating to medicament injection apparatus - Google Patents

Description

Improvements in and relating to medicament injection devices

Technical Field

The present invention relates to a medicament injection device. The invention is particularly, but not exclusively, applicable to electronically controlled injection devices whereby self-administration of a dose of medicament is enabled.

Background

Such devices typically utilize a medicament cartridge that stores medicament and includes a microprocessor that controls a drive mechanism to deliver controlled doses of medicament through a needle device. The device is small enough to be easily carried around by a user. As such, the device is particularly suitable for use by people with diabetes.

The present invention is also applicable to other kinds of medicament injection devices, for example, an injection device in which, although the dose setting and dose delivery are purely mechanical in nature, a timer is actuated after completion of a dose delivery to indicate the time elapsed since completion of the dose delivery.

In each case, in use, once a desired dose of medicament has been selected, the needle of the medicament injection device is inserted into the patient. The drive mechanism is then actuated to cause the selected dose of medicament to be expelled from the medicament cartridge into the patient.

However, it is necessary to locally diffuse the injected medicament from the injection site in the patient as soon as the injection is completed, before the needle device is withdrawn from the patient.

There are problems with known drug injection devices: the injection interval, i.e. the time elapsed since the previous injection, is measured after completion of a delivery stroke, rather than from the time after diffusion of the injected medicament.

Disclosure of Invention

According to a first aspect of the present invention, in a medicament injection apparatus, the time elapsed after an injection operation is counted from the end of a predetermined period of time during which medicament is allowed to diffuse following completion of an injection stroke.

Such an injection device has the advantage that the injection interval is measured from the end of the diffusion period.

Preferably, the medicament injection device provides a signal after the injection operation is completed. This has the advantage that the user does not inadvertently withdraw the medicament injection device until the medicament has been dispersed.

According to a second aspect of the present invention there is provided a method of operating a medicament injection apparatus comprising a processor having a timer, a medicament cartridge containing medicament, a needle (needle unit) allowing medicament to be expelled from the medicament cartridge and a drive means to cause medicament to be expelled from the medicament cartridge, the method comprising the steps of:

i) operating the drive means to expel medicament from the medicament cartridge;

ii) starting a timer to measure a predetermined time upon completion of step i);

iii) resetting the timer upon completion of step ii) to measure the time elapsed since step ii).

Preferably, step ii) also includes generating a signal to be emitted upon completion of step ii).

Preferably, the method further comprises displaying the time elapsed since step ii) simultaneously with step iii).

Drawings

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which;

fig. 1 shows an exemplary arrangement according to the invention.

Detailed Description

Referring to the drawings, there is disclosed a schematic arrangement of a medicament injection device according to the present invention. The medicament injection apparatus 2 comprises a housing 4, a control unit or microprocessor 6, a drive means 8, a piston 10 and a needle 12. A medicament cartridge 14, which is preferably replaceable, is located between the piston 10 and the needle 12. The medicament cartridge 14 comprises a closure member at a first end adapted to be pierced by the needle and a movable plunger located towards a second end of the medicament cartridge and adapted to be driven by the piston 10 towards the first end of the medicament cartridge 14.

The control unit or microprocessor 6 includes a timer. In use, a dose of medicament to be injected is set. The drive means 8 is then actuated to drive the piston 10. The drive means 8 may be actuated mechanically or under the control of a control unit or microprocessor 6. The medicament within the medicament cartridge 14 is then expelled from the medicament injection apparatus 2.

In the embodiment shown, the microprocessor 6 operates the drive means 8 to advance the piston 10. However, in an alternative embodiment, the drive means may be operated manually to advance the piston. In the latter case, the microprocessor monitors the operation of the drive. In each case, the piston is advanced to expel a dose of medicament from the medicament cartridge.

The medicament injection apparatus 2 may also include other elements for performing other functions as desired and known in the art.

A timer connected to the control unit or microprocessor 6 is activated upon completion of the movement of the piston 10, an injection stroke. A predetermined period of time is then allowed to elapse to allow the drug to diffuse within the patient. At the end of this first period of time, the timer is reset to zero and actuated again. The timer now records the injection interval according to the present invention.

The medicament injection apparatus 2 may additionally incorporate a display 16. The display may conveniently comprise an LCD display. The display 16 may be used to indicate the duration of the injection interval.

The medicament injection apparatus 2 may also incorporate a signalling device 18, such as a sound emitter, to signal to the user that the diffusion time has elapsed and that the needle can be withdrawn. Alternatively, the user may indicate the injection interval on display 16 as a sufficient indication that the diffusion time has elapsed.

A user of the medicament injection device 2 first operates the medicament injection device 2 to select a dose of medicament to be injected by the medicament injection device 2. The needle 12 is then inserted into the patient to inject the medication. The medicament injection device 2 is then operated to advance the piston 10.

The user must then pass a short period of time to allow the drug to diffuse. If the needle 12 is withdrawn too quickly, the drug may escape through the needle wound, resulting in the injection of an incorrect dose of drug. Thus, when a predetermined time has elapsed after the injection stroke, the microprocessor 6 sends either or both a visual and an audible signal to indicate that the needle 12 may be withdrawn from the patient. If an audible signal is required, a sounder 18 may be used to generate the signal.

While the signal is being given, the microprocessor 6 resets the timer to zero and then measures the elapsed time since the signal was given. The time elapsed since the signal was given may be indicated to the user on the display 16.

Claims (5)

1. A medicament injection apparatus configured to contain a medicament cartridge (14) containing medicament, the medicament injection apparatus comprising drive means (8) to cause medicament to be expelled from the medicament cartridge, characterised by a control unit (6) having a timer, wherein the timer measures a predetermined time from when the drive means completes an injection stroke during which the medicament is allowed to disperse after completion of an injection stroke, and the control unit (6) resets the timer at the end of the predetermined time to measure the time elapsed after the injection stroke.

2. A medicament injection apparatus according to claim 1, in which the medicament injection apparatus signals the end of the injection operation.

3. A medicament injection apparatus according to claim 1 or 2, in which the medicament injection apparatus further comprises a display to indicate the time elapsed after the injection operation.

4. A medicament injection apparatus according to claim 1 or 2, in which the medicament injection apparatus further comprises means for indicating the end of the predetermined period of time from the completion of the injection operation by the drive means.

5. A medicament injection apparatus according to claim 3, in which the medicament injection apparatus further comprises means for indicating the end of the predetermined period of time following completion of the injection operation by the drive means.