WO2009053914A1

WO2009053914A1 - Implantable drug delivery system

Info

Publication number: WO2009053914A1
Application number: PCT/IB2008/054357
Authority: WO
Inventors: Ventzeslav P. Iordanov; Hendrika C. Krijnsen; Michel P. B. Van Bruggen; Anna-Maria Janner
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2007-10-25
Filing date: 2008-10-22
Publication date: 2009-04-30

Abstract

An implantable drug delivery system is provided, comprising a reservoir for comprising a drug to be delivered, a pump (27) for delivering the drug to a patient, an actuator (22) for operating the pump, a monitoring sensor (12) for monitoring a performance of the system and a power source (13, 23) for providing power to the system. The system comprises at least two separate units. An actuator unit (20) comprises an actuator controller (21) and the actuator (22), the actuator controller (21) being arranged to control the actuator (22). A sensor unit (10) comprises a sensor controller (11) and the monitoring sensor (12), the sensor controller (11) being arranged for switching off the actuator unit (20) in dependence of the monitored performance.

Description

Implantable drug delivery system

FIELD OF THE INVENTION

This invention relates to an implantable drug delivery system, comprising a reservoir for comprising a drug to be delivered, a pump for delivering the drug to a patient, an actuator for operating the pump, a monitoring sensor for monitoring a performance of the system, and a power source for providing power to the system.

BACKGROUND OF THE INVENTION

Such an implantable drug delivery system is, e.g. known from the United States patent application published as US 2002/0065540. Said application discloses an implantable infusion pump, controlled by operating software in two processor ICs. Each processor controls a different part of the drug infusion mechanism such that both processors must agree on the appropriateness of drug delivery for infusion to occur. Both processors are programmed to independently calculate when infusion should occur which in turn dictates when they should perform their separate functions. Both processors comprise a watchdog monitor circuit for noticing when the processor ceases to properly execute instructions. In one embodiment, both processors are included in one hybrid circuit. US 2002/0065540 also suggests combining the functionality of both processors into one processor.

It is a disadvantage of the system disclosed in US 2002/0065540, that malfunctioning of one of the processor may hinder the proper delivery of the drug as well as the monitoring function of the watchdog circuit. Consequently, the malfunctioning may jeopardize the patient's health.

OBJECT OF THE INVENTION

It is an object of the invention to provide an implantable drug delivery system according to the opening paragraph, which system provides improved safety to the patient.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, this object is achieved by the system comprising at least two separate units, being an actuator unit comprising an actuator controller and the actuator, the actuator controller being arranged to control the actuator, and a sensor unit comprising a sensor controller and the monitoring sensor, the sensor controller being arranged for switching off the actuator unit in dependence of the monitored performance. The separate sensor unit is capable of monitoring the system performance independently from the actuator unit. In the event of a malfunctioning of, e.g. the actuator unit or the actuator itself, the sensor unit will detect the malfunctioning and may stop the actuator unit operating the pump by, e.g. switching it off completely, possibly followed by an alarm signal. Hence, the safety of the patient is protected. Malfunctioning of, e.g. the sensor unit may also cause switching off of the actuator unit. If the actuator unit is not turned on yet, the malfunctioning may cause the actuator not to be turned on at all. Preferably, in the event that the actuator is on, but does not receive expected commands from the sensor unit it will automatically switch itself off.

It is a further advantage of the system according to the invention, that when separating the sensing and actuating functions of the system, the actuator unit may remain in power-off mode until an actual drug delivery is to occur. The actuator unit may return into power-off mode directly after the drug delivery. Meanwhile, the sensor unit performs the necessary monitoring functions. In prior art systems without function separation, the whole system is turned on when performing monitoring functions. Consequently, the system according to the invention has lower power consumption and the lifetime of the total device is thereby extended.

In a preferred embodiment, the actuator unit further comprises a receiver, coupled to the actuator controller, for receiving actuator control programs and the sensor unit further comprises a transmitter, coupled to the sensor controller, for reporting the monitored performance.

When a change in program configuration (e.g. delivery profile) is required the instruction set may be received by the actuator unit, communicated to the sensor unit and transmitted back for verification, followed by an acknowledgement received by the actuator unit. Since this is required rarely the receiver part will be most of the time switched off leading to additional power savings. An external data/instruction transmission request may be communicated to the system via any of the wake up units or the start up unit.

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Figure 1 schematically shows an implantable drug delivery system according to the invention, Figures 2a and 2b show sensors for monitoring drug delivery,

Figures 3 a and 3b show sensors for monitoring the operation of the actuator, Figure 4 shows a block diagram of an operation protocol for the system according to the invention, and

Figure 5 shows a block diagram of another operation protocol for the system according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 schematically shows an implantable drug delivery system according to the invention. The system comprises a sensor unit 10 and an actuator unit 20. Each unit 10, 20 comprises a respective controller 11, 21 for controlling the operation of the unit 10, 20. The use of separate controllers 11, 21 allows the sensor unit 10 to function independently from the actuator unit 20. As a result, power is saved and security is enhanced. The sensor controller 11 may be coupled to other units, such as for example, one or more sensors 12, a power source 13, a transmitter 14, a start up unit 15 and a wake-up unit 16. An actuator 22, a power source 23 and a receiver 24 may, e.g. be coupled to the actuator controller 21.

A pump 27 is provided for controlled delivery of a drug to the patient. In order to obtain a miniature system the device will deal with a small volume reservoir (e.g. up to 2 ml), where only potent, highly concentrated, drug may be used. Since these highly concentrated drugs are lethal if overdosing occurs, it is extremely important that the performance of the system is continuously and accurately monitored.

The sensors 12 monitor the performance of the system. For example, a sensor 12 may check power levels for the sensor unit 10 and the actuator unit 20, function parameters of, e.g. the actuator controller 21, the actuator 22, the transmitter 14 or the receiver 24. In order to verify whether a dosing step really takes place, several different types of sensors 12 may be used, such as electrical (resistive or capacitive), magnetic, optical, etc. A sensor may also be provided for monitoring the functioning of the pump 27 that is driven by the actuator 22.

Preferably, also sensors 12 are provided for monitoring environmental and physiological parameters. For example, a sensor 12 may monitor a temperature, blood pressure, heart rate, drug concentration or blood sugar level of the patient. Based on the monitored device parameters and external parameters, the sensor controller 11 determines whether the system is functioning as it should. Only when the system is functioning as expected, the actuator controller 21 may be allowed to run a control program for operating the actuator 22. It is thus avoided that drug is delivered to the patient when the system is not functioning well. The physiological and environmental parameters may be used for determining to adapt the scheme or dosage for the drug delivery.

The respective power sources 13 and 23 may alternatively be embodied as one power source for supplying power to both units 10, 20. Using a single power source has the advantage that the system only stops functioning when all power is consumed. Using two separate power sources 13, 23 brings the advantage that the sensor unit 10 may still function when the actuator's unit 20 power source 23 malfunctions. The sensor unit 10 may then, e.g. send a warning message to the patient before powering down the whole system.

The actuator unit 20 may comprise a receiver 24 for receiving instructions or system configuration settings. For example, a dosage program may be received. The actuator controller 21 executes the dosage program to let the actuator 22 operate the pump 27. The drug is only delivered when the sensor controller 11 allows the actuator unit 20 to do so. Preferably, the sensor controller 11 uses a predetermined time schedule for instructing the actuator unit 20 to deliver the drug. The delivery instruction is only provided if all monitored parameters indicate that the system is functioning as desired. The receiver 24 may also be used for external control of drug deliveries, e.g. in discrete steps, triggered from outside for bypassing the sensor unit or in the event of sensor unit malfunctioning.

The sensor unit 10 may comprise a transmitter 14 for sending operation details, monitored parameters, warning messages or other information from the implantable drug delivery system to an outside receiver. In a preferred embodiment, changes received by the receiver 24 are sent back via the transmitter 14 to verify whether the information was received and interpreted correctly. In this embodiment, the system ensures in a simple manner that both units (sensor and actuator unit) correctly receive and understand new (external) instruction. The receiver 24 and/or the transmitter 14 may alternatively be embodied as transceivers being capable of transmitting as well as receiving data. In another embodiment all transmission and receiving functionality may be comprised in one transceiver in the sensor unit 20. In such an embodiment data directed to the actuator controller 21, is passed to the actuator controller 21 via the sensor controller 11. A start up unit 15 may be used for initially starting up the system after being implanted in the patient. Preferably, the start up circuit 15 is triggered by an external signal, e.g. via electrical induction. Alternatively, an internal clock may determine the moment for starting up the system. A wake up circuit 16 is used for waking up the sensor unit 10 upon an external wake up request. Alternatively, the sensor unit may wake up itself periodically or according to a predetermined and programmed time schedule. This allows the sensor unit 10 to power down when not being active for saving battery power. The wake up circuit 16 then waits for a subsequent internal or external trigger for initiating activity of the sensor unit. The start up circuit 15 and the wake up circuit 16 may be based on simple low frequency resonance circuits (e.g. L(R)C), followed by filtering, amplification and recognition stages. Preferably, the actuator unit 20 powers down independently from the sensor unit 20, directly after each drug delivery activity. The actuator unit 20 is activated or started up again when a subsequent drug dosage is to be delivered. The actuator unit 20 may, e.g. be activated by the sensor controller 11. The actuator unit 20 may comprise a wake up circuit 26 of its own. The wake up circuit 26 may be used for activating the unit for enabling data transmission from outside to the actuator unit.

Figure 2a shows a drug delivery channel 120 for delivering the drug to the patient. The drug delivery channel 120 comprises a pressure sensor 121 and/or a flow sensor 121. A pressure sensor 121 can measure the increase of pressure when the actuator 22 and the pump 27 are activated. The pressure information may, e.g. be used to count discrete steps of drug delivery. A flow sensor 121 may monitor the flow of the drug in the delivery channel 120 to determine how much drug is delivered to the patient.

Figure 2b shows a sensor comprising a light source 122 and a light sensor 123 for detecting, e.g. fluorescent particles 124 comprised in the delivered drug. The fluorescent particles 124 may be an active part of the drug or may only be mixed with the drug to enable monitoring the drug delivery. The drug delivery is monitored using the light source 122 and light sensor 123. The light source 122, e.g. a LED source, sends light to the area just outside the drug delivery channel 120 and close to the position where the drug is delivered. The fluorescent particles 124 reflect the light and the light sensor 123 detects the reflected light. Immediately after the delivery of the drug, the detector signal from the light sensor 123 will be at a maximum. The light sensor 123 signal will fade in time due to diluting of the particles 124.

Figures 3 a and 3b show sensors for monitoring the operation of the pump 27. In figure 3a, the actuator 22 operates a rotational peristaltic pump. The pump 27 comprises a rotational drum 131, with a one or more of shadowers 130, coupled to it. In dependence of the rotational angle of the drum 131, the shadowers 130 may or may not block light going from a light source 125 to a light sensor 126. By monitoring the signal from the light sensor 126, the operation of the pump 27 is monitored directly. In figure 3b the pump 27 comprises a piston 127 based pump. The drug delivery channel 120 comprises a resistive material 128 covering the path of the piston 127 through the channel 120. The resistive material 128 is electrically coupled to the piston 127. The electrical resistance 129 measured between the piston 127 and a reference point on the resistive material 128 is a measure for the position of the piston in the channel. The pump performance is thus monitored by observing the electrical resistance 129.

Figure 4 shows a block diagram of an exemplary operation protocol for the system according to the invention. In step 201 the sensor unit 10 powers up using the start up circuit 15 and starts monitoring the actuator unit 20. If an unexpected performance is detected, the protocol proceeds to step 207 for immediately switching off the actuator unit 20. Then the transmitter 14 is used for sending an alarm message to an external receiver in step 208. For example, the user may have a small operation device for communicating with the implanted system. In step 209, the system is turned into a safe mode and waits for reconfiguration instructions.

If after start up 201 the actuator unit 20 seems to work as expected, the actuator unit 20 is activated in step 202. Then in step 203, the sensor controller 11 checks all sensors 12 for determining whether a drug delivery should and can occur. If not, the actuator unit 20 is turned off in step 210 and the system waits for new instructions. If a drug delivery is needed and all sensors 12 indicate that the system is working properly, then the pump actuator 22 is activated in step 204. During step 205, the pump delivers the drug to the user, while the sensors 12 keep monitoring the actuator performance. If an actuator step fails or other unexpected things happen, the transmitter 14 sends an alarm message to the external receiver in step 211. Then, in step 209, the system is turned into a safe mode and waits for reconfiguration instructions. If the drug delivery 205 is performed successfully, the sensor unit 10 may send some operational data through the transmitter 14 in step 206. Before switching off the whole system, the system may wait for eventual new instructions, received by receiver 24. If the whole system remains off until a new external start up signal is received, total power consumption is minimized.

Figure 5 shows a block diagram of another operation protocol for the system according to the invention. The protocol differs from the protocol of figure 4 in the following aspects. After the sensor unit 10 powers up for the first time in step 300, using the start up circuit 15, it remains operative till the end of pump lifetime. Then, the sensor unit may enter a sleep mode in step 301. In step 301, the wake up circuit 16 is triggered by an internal clock or an external request and checks whether the actuator unit 20 is operating as expected. Then, in depending on the outcome of this check, the protocol proceeds with step 202 or 207 as described above with reference to figure 4. After sending the operational data to through the transmitter in step 306, the system is not switched off completely, but returns into the sleep mode. In the sleep mode, the actuator unit 20 may be turned off completely, but the wake up circuit 16 in the sensor unit keeps active and waits for a wake up call. The wake up call may be a software-based trigger incorporated in the sensor unit program or may come from an external source.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS:

1. An implantable drug delivery system, comprising: a reservoir for comprising a drug to be delivered, a pump (27) for delivering the drug to a patient, an actuator (22) for operating the pump, - a monitoring sensor (12) for monitoring a performance of the system, a power source (13, 23) for providing power to the system, wherein the system comprises at least two separate units, being: an actuator unit (20) comprising an actuator controller (21) and the actuator (22), the actuator controller (21) being arranged to control the actuator (22), and - a sensor unit (10) comprising a sensor controller (11) and the monitoring sensor (12), the sensor controller (11) being arranged for switching off the actuator unit (20) in dependence of the monitored performance.

2. An implantable drug delivery system according to claim 1, wherein the actuator unit (20) further comprises a receiver (24), coupled to the actuator controller (21) for receiving actuator control programs.

3. An implantable drug delivery system according to claim 1, wherein the sensor unit (10) further comprises a transmitter (14), coupled to the sensor controller (11), for reporting the monitored performance.

4. An implantable drug delivery system according to claim 1, wherein the power source comprises an actuator power source (23) for providing power to the actuator unit (20) and a sensor power source (13) for providing power to the sensor unit (10).

5. An implantable drug delivery system according to claim 1, wherein the sensor unit (12) further comprises an environmental sensor for monitoring environmental parameters.

6. An implantable drug delivery system according to claim 5, wherein the sensor controller (11) is arranged for adapting a drug administration schedule in dependence of the monitored environmental parameters.

7. An implantable drug delivery system according to claim 1, wherein the sensor unit (10) comprises a sensor unit wake up circuit (16), for turning on the sensor unit (10) according to a predetermined schedule.