US 20080172044 A1
A drug delivery device which includes a fluid drug reservoir, a catheter, a controllable fluid transfer device, e.g., a pump mechanism or valve, and a drug delivery control means. The drug delivery control means comprises a controller, e.g., a microprocessor or microcontroller which is operable to automatically reduce the rate of drug delivery over a certain reduction interval (e.g., multiple days) from an initial dosage value to a final dosage value.
17. An implantable drug delivery device, comprising:
an implantable housing configured for implantation into a body;
a reservoir within the implantable housing;
a fluid transfer device within the implantable housing in fluidic communication with the reservoir; and
means, carried within the implantable housing, for repeatedly modifying an entire stored delivery profile including at least one delivery rate in response to a single receipt of modification data.
18. An implantable drug delivery device as claimed in
19. An implantable drug delivery device as claimed in
20. An implantable drug delivery device as claimed in
21. An implantable drug delivery device as claimed in
22. An implantable drug delivery device as claimed in
23. A method of operating an implantable drug delivery device, comprising the step of:
repeatedly modifying a delivery profile that includes a plurality of delivery rates and is stored within the implantable drug delivery device with the implantable drug delivery device in response to a single receipt of wirelessly transmitted modification data.
24. A method as claimed in
receiving wirelessly transmitted modification data with the implantable drug delivery device while the entire implantable drug delivery device is carried within a patient's body.
25. A method as claimed in
(1) creating a modified delivery profile by reducing the delivery rates in the stored delivery profile,
(2) storing the modified delivery profile for a predetermined period, and
(3) repeating steps (1) and (2) after the expiration of the predetermined period.
26. A method as claimed in
27. A method as claimed in
28. A method as claimed in
the modification data comprises a reduction ratio having a value less than 1.0; and
the step of creating a modified delivery profile comprises multiplying the delivery rates in the delivery profile by the reduction ratio.
29. A method as claimed in
the step of repeating steps (1) and (2) comprises repeating steps (1) and (2) after the expiration of the predetermined period a plurality of times over the course of a plurality of days in response to a single receipt of wirelessly transmitted modification data.
30. A method of modifying the dosage of a drug supplied by a drug delivery device that stores a delivery profile including at least one delivery rate and is located entirely within a patient, the method comprising the steps of:
wirelessly transmitting a final daily dosage value to the drug delivery device located entirely within the patient;
wirelessly transmitting a reduction rate or a reduction interval to the drug delivery device located entirely within the patient; and
allowing the drug delivery device located entirely within the patient to itself iteratively reduce the at least one delivery rate over the course of a plurality of days as a function of the transmitted final daily dosage value and the transmitted reduction rate or as a function of the transmitted final daily dosage value and the transmitted reduction interval.
31. A method as claimed in
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34. A method as claimed in
35. A method as claimed in
36. A method of operating an implantable drug delivery device, comprising the steps of:
initiating a dosage reduction mode in response to a single event; and
modifying a delivery profile that includes one or more clinically significant delivery rates and is stored within the implantable drug delivery device by reducing the one or more clinically significant delivery rates to one or more lower clinically significant delivery rates with the implantable drug delivery device in response to the initiation of the dosage reduction mode.
37. A method as claimed in
38. A method as claimed in
39. A method as claimed in
This application is a CIP of U.S. application Ser. No. 11/069,573 filed on 28 Feb. 2005 which is incorporated herein by reference. This application claims the benefit of U.S. Provisional Application 60/604,999 filed on 27 Aug. 2004 which is incorporated herein by reference.
This invention relates generally to medical devices for delivering a medication, or drug, to a body site at flow rates and times specified by a stored drug delivery profile. More particularly, this invention relates to such devices which can operate to automatically gradually modify rates of drug delivery to achieve a desired target dosage.
Various implantable drug delivery devices are known in the art which can be programmed to deliver a drug to a body site for infusion at flow rates and times dictated by a stored drug delivery profile. Such delivery devices typically include a refillable reservoir for storing a fluid drug and a controllable fluid transfer device (e.g., a pump or valve) for transferring fluid from the reservoir to a catheter for delivery to the body site. The drug delivery profile comprises a data set specifying a schedule of flow rates for a periodic cycle, or period, of a certain duration. For example, the duration of a period can be twelve hours, twenty four hours, or one week, etc. The particular profile used to control drug delivery is typically specified by the patient's clinician and depends upon several factors including the particular drug formulation being delivered, the patient's condition, the therapy being administered, etc.
The delivery profile is typically stored in the medical device at the time of implanting and can thereafter be modified by a clinician (using an external controller or programmer) when the patient periodically visits for a refill/checkup, e.g., once per month.
In the course of certain drug therapies, it may be desirable to increase or reduce the drug dosage delivered to the patient. For example, in some situations, it may be helpful to reduce or terminate drug administration for a limited period in order to increase the patient's sensitivity to the drug. In still other situations, it may be desirable to terminate delivery of a drug as an initial step in preparation for changing the drug formulation.
For illustrative purposes, in situations where a therapeutic decision has been made to reduce or eliminate delivery of a certain drug, it is generally desirable to reduce the drug dosage gradually. This gradual reduction, which is sometimes referred to as a detoxification procedure, is relatively easy to administer if the patient is available to the clinician on a frequent basis, e.g., daily. However, in the use of implanted drug delivery devices, patients typically visit their clinicians infrequently, e.g., once per month, and it has therefore been inconvenient and impractical to administer a drug modification program. The present invention is directed to an implantable drug delivery apparatus and method of operation which facilitates the automatic gradual modification, e.g., reduction of drug delivery over an extended interval, e.g., many days.
The present invention relates to a drug delivery device which includes a fluid drug reservoir, a catheter, a controllable fluid transfer device, e.g., a pump or valve mechanism, and a drug delivery controller. The controller, e.g., a microprocessor, is operable in accordance with the invention, to automatically gradually reduce the rate of drug delivery specified by a stored delivery profile from a current dosage value to a targeted final dosage value.
In accordance with a preferred embodiment, dosage reduction is achieved over an interval comprised of multiple periods, where a period may, for example, comprise 4, 12, or 24 hours. An initial delivery profile specifies an initial delivery rate (or rates). Delivery rates for each subsequent period within the reduction interval are determined by applying a calculated reduction rate (typically a percentage) to the delivery profile for the preceding period. In this manner, the initial delivery profile is incrementally reduced in steps to ultimately achieve a delivery profile specifying the desired final dosage value.
For example, in a preferred embodiment, a clinician may specify a final dosage value and the duration of the reduction interval (which can be expressed in number of periods). Based on this information and the initial dosage information contained in the stored initial delivery profile, a system in accordance with the invention operates to calculate a reduction rate which is then used to periodically reduce the delivery rates until the rates appropriate to the final dosage value are reached.
The preferred embodiment also enables the clinician to alternatively specify a periodic (e.g., daily) dosage reduction rate thus enabling the system to then calculate the duration of the reduction interval (e.g., number of days).
Although in many applications, it suffices to calculate and reduce delivery rates on a daily basis, it is recognized that for more rapid dosage reduction, or detoxification, delivery rates can be reduced more frequently by partitioning the 24 hour daily period into subperiods of, for example, 2 hours, 4 hours, or 8 hours.
Attention is initially directed to
As depicted in
Programmer device 16 is shown as including a controller 34 (sometimes hereinafter referred to as a microprocessor which operates in conjunction with memory 35 which stores programs and/or data. The device 16 optionally includes a user input device 36, e.g., a keyboard, and a user output device 37, e.g., a display. The programmer 16 further include aforementioned telemetry subsystem 19 configured to transmit signals to or receive signals from the medical device telemetry subsystem 18. The programmer 16 may further include an internal power source 38 which can comprise a battery or any other suitable conventional power source.
In a typical system 10, the programmer 16 is capable of sending messages to the medical device 14 for use by microprocessor 22 to affect the operation of its therapeutic administration subsystem 26. Additionally, the medical device 14 is typically capable of sending messages to the communication device 16 to report various conditions, e.g., battery status, drug reservoir status, etc. These respective messages sent by the programmer 16 and medical device 14 are handled by the respective telemetry subsystems 19 and 18, each of which is able to transmit and receive RF telemetry signals. Typically, these RF telemetry signals comprise bit streams carried by an RF carrier signal of specified frequency.
In typical use, a hypodermic needle (not shown) is used, via fill port 44, to fill the reservoir 43 with a first drug. The fluid transfer device 45 is controlled by controller 50 in accordance with a stored drug delivery profile comprising a set of data which specifies a schedule of drug flow rates over a certain period, e.g., having a duration of twenty four hours.
When a dosage reduction operation is initiated in accordance with the present invention, the profile 52 is iteratively processed to successively produce profiles 55, 56, 57, 58, etc. of diminishing amplitude.
Attention is now directed to
Before proceeding with the description of the flow chart of
D0=Initial daily dosage (ML/day)
DN=Daily dosage on day N (ML/day)
Rday=Daily reduction rate (%/day)
RP=Periodic reduction rate (%/pd.)
P=Reduction period (hours)
RR=Periodic reduction ratio (1−RP) (%)
N=Reduction interval (days)
If the initial D0 and final DN daily dosages are known and it is desired that the reduction occur over a fixed reduction interval, equation (1) can be rewritten to find the daily reduction rate.
If the reduction rate Rday, initial dosage D0, and final dosage DN are known, this equation can be solved for the number of days N.
For rapid dosage reduction, it is possible to reduce the dosage several times a day instead of once a day. If this is done, it is still possible to specify the total daily reduction as either a percentage or a ratio. The following equation shows how to convert from a daily reduction ratio to a reduction ratio that is applied every P hours.
The periodic reduction ratio is that fraction by which each delivery rate in the delivery profile is multiplied at the beginning of every reduction interval (P). This is shown in equation (5).
With continuing reference to
Decision block 110 asks if the reduction rate Rday was specified. If YES, operation branches to decision block 112 which asks if the final dosage value DN is less than 0.05 times the initial dosage value D0. If YES, block 114 is executed to adjust the final dosage value DN to 0.05 times D0. This operation is performed to terminate profile reduction at a value of DN which is clinically insignificant but greater than zero. If profile reduction were allowed to continue until DN reached zero, the reduction would iterate indefinitely in attempting to asymptotically reach zero. Operation then proceeds to block 116 which computes aforementioned equation (3) to determine the reduction interval N. If decision block 112 yielded a NO, block 114 is skipped.
If decision block 110 yields a NO, operation proceeds to block 118 which computes aforementioned equation (2) to determine the daily reduction rate Rday.
From either block 116 or 118, operation proceeds to block 120 which computes aforementioned equation (5) to determine the periodic reduction ratio RR. Thereafter (block 122), the programmer 16 transmits various values to reprogram the pump 14 including periodic reduction ratio RR, reduction period P, and the reduction interval N. This action (block 124) completes the activity of the programmer in the execution of the automatic dosage reduction mode in accordance with the invention.
Attention is now directed to
Block 202 sets a timer (MinutesTillRed) to a count value equal to sixty times the reduction period P. The microprocessor 22 can then sleep (block 204) to conserve power until the beginning of the next minute. The MinutesTillRed count is then decremented by one minute (block 206).
Decision block 208 then asks is the MinutesTillRed count equal to zero, or in other words, is it now time to reduce the delivery rate. If NO, operation loops back to block 204. Operation continues to loop through blocks 204, 206, 208 until decision block 208 yields a YES. A YES result from block 208 resets the MinutesTillRed count (block 210) to 60×P.
Block 214 then executes one reduction step by multiplying each rate in the current profile by the periodic reduction ratio RR; i.e., Rate (n)=Rate (n) times RR. Since RR always has a value less than one, this multiplication will, of course, reduce the value of Rate (n) in the up-dated current profile.
Block 216 then decrements the RedStop count by one. Block 218 then asks if the RedStop count is equal to zero. If NO, operation loops back to block 204. If YES, operation proceeds to block 220 which allows the pump 14 to continue to deliver drug in accordance with the current updated profile.
From the foregoing, it should now be understood that a drug delivery apparatus and method of operation has been disclosed herein for automatically and gradually reducing delivery rates. Although only a single preferred exemplary embodiment has been described, it is intended that the appended claims be interpreted to encompass variations and modifications which will be apparent to those persons skilled in the art.