Medicine reservoir for drug delivery device

A medicine reservoir (10) is provided for use with a drug delivery device (50). The medicine reservoir (10) is arranged for comprising a drug (13) and comprises a dispensing hole (15) for dispensing the drug (13) into an environment of the drug delivery device (50). The medicine reservoir (10) further comprises a deformable plug (14) which plug (14) is removable by pressure caused by a dispensing action of the drug delivery device (50).

FIELD OF THE INVENTION

This invention relates to a medicine reservoir for use with a drug delivery device, the medicine reservoir being arranged for comprising a drug and comprising a dispensing hole for dispensing the drug into an environment of the drug delivery device.

This invention further relates to a drug delivery device comprising such a medicine reservoir.

BACKGROUND OF THE INVENTION

Such drug delivery devices make it possible to control the release of drugs in the gastrointestinal tract. The drug delivery may take place in accordance with a predetermined delivery schedule and/or may be triggered by external signals or environmental conditions. The device may include additional electronics, sensors and communication devices for controlling the drug delivery. In many swallowable drug delivery devices, the drug release is effected using a displacement based actuator system. For example, a piston may push a predetermined amount of the drug through the dispensing hole.

The dispensing hole often is an open orifice. However, an open orifice introduces the possibility for exchange of material between the reservoir and outside environment, resulting, for example, in delivery of the drug before the intended time and a reduction of the amount delivered when intended. The main processes involved are diffusion and convection. Diffusion, because of the open connection between the inside and the outside of the capsule. Convection, because of small differences in specific weight of the substance stored in the capsule and the fluid outside. E.g. when the fluid in the capsule is heavier than the fluid in the intestines and the hole is directed downwards the fluid in the capsule flows out and will be replaced by the fluid of the intestines. Both processes may be slowed down by reduction in the exit hole cross-sectional size, extending the length of the exit hole and increasing the viscosity of the material in the reservoir. However the hole dimensions and the viscosity of the medicine to be administered must be chosen such that it allows the actuator to dispense the medicine.

Often, a valve is used for separating the drug reservoir from the outside environment. Valves which operate in small spaces, provide good sealing and use low power are however very difficult to implement. It would thus be advantageous to avoid diffusion or convection of the drug without the use of a valve.

OBJECT OF THE INVENTION

It is an object of the invention to provide a medicine reservoir for a drug delivery device according to the opening paragraph, which device does not need a valve for keeping the drug inside until the intended moment of release.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, this object is achieved by providing a medicine reservoir for use with a drug delivery device, the medicine reservoir being arranged for comprising a drug and comprising a dispensing hole for dispensing the drug into an environment of the drug delivery device, the medicine reservoir further comprising a deformable plug which plug is removable by a pressure caused by a dispensing action of the drug delivery device.

As long as no drug is delivered, the plug seals the dispensing hole and no drug is allowed to leave the medicine reservoir. When the drug delivery device tries to deliver a first amount of the drug, the pressure inside the medicine reservoir increases. The resulting pressure upon the plug then causes the plug to be pushed out of the dispensing hole, thereby enabling the delivery of the drug to the environment. The composition and dimensions of the deformable plug are such that the plug is easily removed by the pressure caused by the first drug delivery. Concurrently, the composition and dimensions of the plug should ensure that the plug will not be removed due to other causes (e.g. temperature changes, gravity, diffusion). A non-deformable plug such as, e.g., a plastic plug would be very suitable for sealing the dispensing hole, but cannot be removed by the dispensing action of the drug delivery device. For easy removal, the plug should be deformable.

A suitable plug may, for example, comprise an oil which does not mix with the drug or the gastro-intestinal fluid. For example, a mineral oil or castor oil is very suitable for use as a plug in a medicine reservoir according to the invention, but other non-rigid materials may also be used. When the plug material does not mix with the drug or the medium outside the drug delivery device, the plug will not disintegrate before the first drug delivery is due. In most drug delivery devices oily materials are very suitable because they do not mix with the watery gastro-intestinal environment or the drugs which are often supplied in a watery solution.

In a preferred embodiment of the medicine reservoir according to the invention, a nozzle is provided for partly filling the dispensing hole, the nozzle comprising the deformable plug. The main advantage of the use of the nozzle is that the same drug delivery device and medicine reservoir may be used for different drugs. Due to differences in, e.g., viscosity, different drugs may require dispensing holes with different dimensions (length and/or diameter). Different nozzles may be designed for different drugs, such that a dispensing hole with optimal dimensions is available for all drug types. The holes in those nozzles are filled with the plug according to the invention. The filled nozzle is then used for sealing the medicine reservoir. When the first amount of drug is to be delivered and the pressure inside the medicine reservoir increases, the plug will be pushed out of the nozzle. The resulting dispensing hole will then have the desired dimensions.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1schematically shows a drug delivery device50with a medicine reservoir according to the invention. The drug delivery device50is a swallowable capsule comprising a drug to be released somewhere along the gastro-intestinal tract of a patient and an actuation mechanism for controlling the amount of drugs to be released and the moment of said release. Although the deformable and removable plug according to the invention is particularly advantageous in combination with swallowable drug delivery devices50, it is to be noted that it may also be used with implantable drug delivery devices. The drug to be released is stored in a compressible medicine reservoir10. The drug may, e.g., be stored as dry powder, dissolved in water or as a gel or liquid. An actuator means12is provided for compressing the medicine reservoir10, resulting in an increase of the pressure inside the medicine reservoir10. Instead of a compressible medicine reservoir10, a rigid reservoir may be used comprising a substance or element which is capable of increasing the pressure inside the reservoir. For example, a balloon filled with a swelling agent may be placed in the rigid reservoir.

The medicine reservoir comprises a dispensing hole15for allowing the drug to be pushed out of the drug delivery device50when the pressure inside the medicine reservoir10increases. The actuator means12may work mechanically using, e.g., a piston. Alternatively, the actuator means12may increase the pressure by sucking in water from the environment or by using chemical reactions for producing water or for expanding a volume of a swelling agent. The drug release may, e.g., be triggered by an internal clock, sensor values from a pH-sensor or trigger signals from an electrical or chemical detector element. If the drug delivery device50comprises means for wireless communication, the drug delivery may be externally triggered. The operation of all electronic functions of the device50is controlled by the processing electronics17and powered by a battery16.

FIG. 2schematically shows (part of) a medicine reservoir10according to the invention. The medicine reservoir10is filled with a drug13and is partially enclosed by a housing11of the drug delivery device50. Here, the housing11of the drug delivery device50is also a wall of the medicine reservoir10. Alternatively, the medicine reservoir10may be a small bag inside the housing11. The medicine reservoir10is separated from the external environment of the drug delivery device50by a dispensing hole15in the housing11of the device. In this Figure, the dispensing hole15is blocked by a deformable plug14. The plug14prevents the drug13from leaking out of the medicine reservoir10.

The plug14may comprise an oil which does not mix with the drug13or the gastro-intestinal fluid outside the drug delivery device50. For example, a mineral oil or castor oil is very suitable for use as a plug14. Other non-rigid deformable materials may also be used. When the actuator means12of the drug delivery device50raise the pressure inside the medicine reservoir10, the deformable plug14will first be compressed and will then be pushed out of the dispensing hole15, followed by the first amount of drugs13to be released.

FIG. 3shows the medicine reservoir ofFIG. 2with the plug removed. When the actuator means12compress the medicine reservoir10, drugs13are pushed out through the dispensing hole15.

FIG. 4shows a medicine reservoir10with a nozzle31comprising a plug14.FIG. 5shows a cross section of the medicine reservoir ofFIG. 4. The main advantage of the use of the nozzle31is that the same drug delivery device50and medicine reservoir10may be used for different drugs13. Due to differences in, e.g., viscosity, different drugs13may require dispensing holes15with different dimensions (length and/or diameter). Different nozzles31may be designed for different drugs13, such that a dispensing hole15with optimal dimensions is available for all drug types. A thick gel does, for example, require a relatively wide dispensing hole15, while more liquid drugs require very narrow dispensing holes15. The hole15in the nozzle31is filled with a plug14as described above. The filled nozzle31seals the medicine reservoir10. When the first amount of drug13is to be delivered and the pressure inside the medicine reservoir10increases, the plug14is pushed out of the nozzle31. The dimensions of the dispensing hole15are defined by the design of the nozzle31.