Medicament injection apparatus

A medicament injection device in which the time elapsed is calculated from the end of a predetermined period during which medicament is permitted to disperse subsequent to completion of an injection stroke. The medicament injection device is particularly suitable for use by those with diabetes in which once a desired dosage of medicament has been selected and expelled from the medicament cartridge into the body of the patient, the injected medicament is allowed to disperse locally from the injection site within the patient's body before the needle arrangement is removed from the patient's body.

FIELD OF THE INVENTION

The disclosure relates to a medicament injection apparatus. In particular, but not exclusively, the disclosure has application for electronically controlled injection apparatus whereby self-administration of a dose of medicament is enabled.

BACKGROUND TO THE INVENTION

Such apparatus generally utilize a medicament cartridge in which a medicament is stored and comprise a microprocessor that controls a drive mechanism to deliver a controlled dosage of medicament through a needle arrangement. The apparatus are small enough readily to be carried about by a user. As such, the apparatus is particularly suitable for use by those with diabetes.

The disclosure is also suitable for other kinds of medicament injection apparatus, for example injection apparatus in which though the dose setting and dose delivery are purely mechanical in character a timer is actuated following completion of a dose delivery stroke to indicate a time elapsed since completion of dose delivery stroke.

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

However, it is necessary once the injection has been made to allow the injected medicament to disperse locally from the injection site within the patient's body before removing the needle arrangement from the patient's body.

It is considered to be a problem that in known medicament injection devices the injection interval, that is the time elapsed since a previous injection, is measured following completion of a delivery stroke rather than from dispersion of the injected medicament.

SUMMARY

According to a first aspect of the disclosure a medicament injection device in which the time elapsed following an injection operation is calculated from the end of a predetermined period during which medicament is permitted to disperse subsequent to completion of an injection stroke.

This has as an advantage that the injection interval is measured from the end of the dispersion period.

Preferably, the medicament injection apparatus provides a signal following completion of the injection operation. This has the advantage that a user will not inadvertently remove the medicament injection apparatus until after the medicament has been allowed to disperse.

According to a second aspect of the disclosure, a method of operation of a medicament injection apparatus comprising a processor having a timer, a medicament cartridge containing medicament, a needle unit to allow medicament to be expelled from the medicament cartridge and a drive means to cause medicament to be expelled from the medicament cartridge comprising the steps ofi) operating the drive means to expel medicament from the medicament cartridge;ii) upon completion of step i) starting a timer to measure a predetermined period;iii) upon completion of step ii) resetting the timer to measure the time elapsed since step ii).

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

Preferably, the method further includes concurrent with step iii) displaying the time elapsed since step ii).

DETAILED DESCRIPTION OF THE EMBODIMENTS

Referring to the Figure, a schematic arrangement of a medicament injection device according to the present invention is disclosed. The medicament injection device2comprises a housing4, a control unit or microprocessor6, a drive mechanism providing a drive means8, a piston10and a needle unit12. A medicament cartridge14, which is preferably replaceable, is located between the piston10and the needle unit12. The medicament cartridge14includes a closure at a first end adapted to be pierced by the needle unit and a moveable plunger located towards a second end of the medicament cartridge and adapted to be driven by the piston10towards the first end of the medicament cartridge14.

The control unit or microprocessor6includes a timer. In use, a dosage of medicament to be injected is set. The drive means8is the actuated to drive the piston10. The drive means8may be actuated mechanically or under the control of the control unit or microprocessor6. Medicament from within the medicament cartridge14is the expelled from the medicament injection device2.

In the illustrated embodiment, the microprocessor6operates the drive means8to advance the piston10. However, in an alternative embodiment, the drive means may be operated manually to advance the piston. In this latter case, the microprocessor monitors the operation of the drive means. In each case, the piston is advanced to expel a dosage of medicament from within the medicament cartridge.

The medicament injection device6may also include other elements for fulfilling further functions as required and known in the art.

The timer associated with the control unit or microprocessor6is actuated on completion of movement of the piston10—the injection stroke. A predetermined period of time is then allowed to lapse to permit dispersion of the medicament within the patient. On completion of this first time period, the timer is reset to zero and actuated once more. The timer now records the injection interval in accordance with the present invention.

The medicament injection apparatus2may additionally incorporate a display16. The display may conveniently comprise an LCD display. The display16may be used to indicate the duration of the injection interval.

The medicament injection apparatus2may further incorporate a signaling device18, such as a sounder, to signal to the user that the dispersion period has elapsed and that the needle unit may be removed. Alternatively, the user may take the indication of the injection interval on the display16as sufficient indication that the dispersion period has elapsed.

A user of the medicament injection device6will first operate the medicament injection device6to select a dosage of medicament to be injected by the medicament injection device6. The needle unit12will then be inserted into a body of the patient to allow the medicament to be injected. The medicament injection device6is then operated to cause the piston10to advance.

The user must then allow a short period to elapse to allow the medicament to disperse. If the needle unit12is removed too quickly the medicament will escape through the needle wound resulting in an incorrect dosage of medicament having been administered. Thus, when a predetermined time has elapsed following the injection stroke the microprocessor6causes a signal, either visual, audible or both, to be given indicating that the needle unit12may be removed from the patient. A sounder18may be used to generate the signal if an audible signal is required.

At the same time as the signal is given, the microprocessor6resets the timer to zero and then measures the time elapsed since the signal was given. The time elapsed since the signal was given may be indicated to a user on the display16.