US 20060047270 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.
1. A fluid drug delivery device comprising:
a reservoir for storing a fluid;
a catheter for transferring fluid from said reservoir to a selected body site, said catheter having a proximal end for receiving fluid from said reservoir and a distal end for delivering fluid to said body site;
a controllable fluid transfer device coupling said reservoir to said catheter proximal end;
a controller storing data defining a delivery rate specifying a quantity of fluid to be delivered to said catheter within a specified period;
a source of modification data;
said controller being responsive to said modification data for iteratively modifying said stored delivery rate; and wherein
said fluid transfer device is responsive to said modified delivery rate for delivering a specified quantity of fluid to said catheter proximal end.
2. The delivery device of
said controller includes means for executing an algorithm to iteratively reduce said stored delivery rate based on said modification data.
3. The combination of
a clinician operable programmer external to said drug delivery device for transmitting said modification data.
4. The combination of
said controller iteratively processes the stored delivery rate and said reduction ratio to produce a modified delivery rate.
5. The combination of
said controller processing includes multiplying the stored delivery rate times said reduction ratio.
6. The combination of
said controller stores a current delivery profile defining at least one delivery rate; and wherein
said controller operates to iteratively multiply said periodic reduction ratio times each delivery rate in said current delivery profile to produce a new delivery profile.
7. The combination of
said controller multiplies said stored delivery rate and said reduction ratio for each of said reduction steps to successively produce new and reduced delivery values.
8. A method of operating an implantable drug delivery device for transferring a drug from a reservoir to a catheter for delivery to a body site, said method including:
providing said reservoir with a first drug;
storing a current dosage value;
generating dosage modification data;
periodically modifying said stored dosage value in accordance with said dosage modification data; and
controllably transferring said first drug from said reservoir to said catheter in accordance with the currently stored dosage value.
9. The method of
10. The method of
said step of periodically modifying comprises iteratively multiplying said stored dosage valve times said reduction ratio.
11. A fluid drug delivery system comprising:
an implantable drug delivery pump including a controller for transferring a fluid drug from said pump at delivery rates defined by a stored drug delivery profile;
an external programmer for generating drug delivery modification data;
said controller includes means responsive to said drug modification data for iteratively modifying said defined delivery rates as a function of said modification data.
12. The system of
for each of said steps said controller modifies the stored drug delivery profile as a function of said modification ratio to successively define modified delivery rates.
13. The system of
for each of said steps said controller modifies the stored drug delivery profile as a function of said reduction ratio to successively define reduced delivery rates.
14. The system of
15. The system of
16. The system of
said controller controls said fluid transfer means in accordance with said defined delivery rates.
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 patients 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
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.