WO2007119178A2 - Infusion pump - Google Patents

Abstract

Embodiments of this invention include implantable pumps for delivery of solutions containing drags into the bodies of patients suffering from disorders for which controlled delivery of the drug is desirable for therapeutic purposes. Pumps include power supplies, processors, memory storage devices, a motor, position and pressure sensors to monitor the state of the pump, and novel linear actuators. Linear actuators include a series of two or more nested, coaxial screws threaded in such a fashion that when a motor rotates, a piston-type plunger is moved linearly inside a reservoir and urges the solution out of the pump, through a catheter located at a pre¬ determined location within the patient, and into a portion of the patient's body to be treated. Embodiments of software system of this invention are energy efficient because most of the time, the pump is in standby mode. Only upon receiving external instructions or internal signals is the pump activated. Thus, pumps can be maintained internally for long periods of time, and are suitable for delivery of drugs to patients with chronic conditions such as those useful for treating neurodegenerative conditions.

Description

INFUSION PUMP

Claim of Priority

This application claims priority to United States Provisional Application No: 60/761,221 filed January 23, 2006, inventors: Suded Mudhaffer Emmanuel and Christopher Edward Williams, titled "Infusion Pump." This application is herein expressly incorporated fully by reference.

Field of the Invention This invention relates to infusion pumps. In particular, this invention relates to implantable pumps useful for infusing neuroactive agents into the brain or other organ of a subject in need of such treatment. More particularly, this invention relates to pumps having telescoping screw-driven mechanisms and mechanisms for remotely controlling operation of the pump.

BACKGROUND Description of the Art

Effective treatment of neurological disorders is a continuing and difficult problem.^' Many people suffer and die as a result of chronic disorders of the central nervous system (CNS), including the brain. In the last several years, understanding of the mechanisms underlying chronic neurological disorders has improved, and several therapeutic approaches are being used.

For example, insulin-like growth factor-1 (IGF-I) and its tri-peptide derivative, glycyl-prolyl-glutamate (Gly-Pro-Glu; GPE) show promise as therapies for conditions characterized by degeneration and/or death of glial cells and neurons. Additionally, other proteins, peptides and synthetic compounds show promise in treating such conditions. However, long-term treatment of disorders of the brain is a likely requirement for treating patients with chronic disorders, such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis and other disorders. Additionally, in patients with a history of stroke or other hypoxic/ischemic damage to the brain, chronic treatment may be required.

Although there has been a recognized need for devices and methods that can be used to infuse agents into the brain, the art is still developing. For example, US Patent Nos: 4,676,248, 5,630,710, 5,711,316, 5,735,814, 6,042,579, 6,635,048, 6,733,476, 6,758,810, 6,796,956, 6,945,969 and 6,950,708 describe various implantable pumps for delivering agents to the brain.

In spite of these advances, there is still a need in the art for reliable, energy efficient pumps that can deliver highly regulated amounts of solutions into the brain of a patient in need thereof.

BRIEF DESCRIPTION OF THE FIGURES

This invention is described with reference to specific embodiments thereof. Other features of embodiments of this invention can be appreciated with respect to the Figures, in which:

Figure 1 depicts a block diagram of an implantable infusion pump of this invention.

Figure 2 depicts a block diagram of a power supply module of an implantable infusion pump of this invention. Figure 3 depicts a block diagram of a central processing unit (CPU) of an implantable infusion pump of this invention.

Figure 4 depicts a block diagram of a radio-frequency (RF) module and RF detection of an implantable infusion pump of this invention.

Figure 5 depicts a block diagram of a real-time clock and CPU and logic of an implantable infusion pump of this invention.

Figure 6 depicts a block diagram of a motor drive module of an implantable infusion pump of this invention.

Figure 7 depicts a block diagram of pressure and position sensors of an implantable infusion pump of this invention. Figure 8 depicts a schematic diagram of a piston-type actuator mechanism of an implantable infusion pump of this invention.

Figure 9 depicts a schematic diagram of a portion of the delivery mechanism shown in Figure 8, showing a telescoping screw of an implantable infusion pump of this invention. Figures 1 Oa-I Oh depict schematic diagrams of latching mechanisms of portions of a telescoping screw of portions of delivery mechanisms of this invention.

Figure 10a depicts an oblique view of telescoping, two-coaxial, threaded screws of an implantable infusion pump according to this invention, with an inner screw fully retracted within an outer screw. Figure 10b depicts an embodiment in which cams of an inner screw are unlatched from slots in an outer screw.

Figure 10c depicts an embodiment in which cams of an inner screw are latched into slots in an outer screw. Figure 1Od depicts a perspective view of telescoping, two-coaxial, threaded screws of an implantable infusion pump according to this invention, with an inner screw fully extended.

Figure 1Oe depicts an oblique view of telescoping, three-coaxial, threaded screws of an implantable infusion pump according to this invention, with an inner screw fully retracted within an outer screw, and with an outer screw fully retracted within a nut.

Figure 1Of depicts an embodiment in which cams of an inner screw are unlatched from slots in an outer screw, and cams of an outer screw are unlatched from slots in a nut. Figure 1Og depicts an embodiment in which cams of an inner screw are latched into slots in an outer screw, and cams of an outer screw are latched into slots in a nut.

Figure 1Oh depicts a perspective view of telescoping, three-coaxial, threaded screws of an implantable infusion pump according to this invention, with an inner screw fully extended, and an outer screw fully extended.

Figures 11a and l ib depict flow charts of programs for controlling an implantable infusion pump of this invention.

Figure 11a depicts a first portion of a flowchart depicting the logic of a CPU of an implantable infusion pump of this invention. Figure l ib depicts a continuation of the flowchart of Figure l la of an implantable infusion pump of this invention.

Figures 12a — 12c depict cross-sectional views of alternative embodiments of solution-containing reservoirs of this invention. Figure 12a depicts an embodiment having an ellipsoidal cross-section. Figure 12b depicts an embodiment having a rectangular cross-section. Figure 12c depicts an embodiment having a contoured cross-section.

•Figure 13a depicts a software flowchart used to compute a dose of a drug to be administered through a pump of this invention. Figure 13b depicts a software flowchart used to compute acceleration/deceleration parameters in dose administration through a pump of this invention.

SUMMARY

The above and other needs in the art are met by a new type of implantable pump. In some embodiments, pumps of this invention have a linear displacement element or "linear actuator," thereby solving one of the problems of inaccuracy that is characteristic of peristaltic pumps. In some embodiments, a linear actuator uses a screw-driven piston to deliver a solution. Thus, when an electric motor turns the screw, the displacement of the screw (e.g., a syringe-like piston) can be made very accurate. Because there may be no need for a resilient element in the solution delivery mechanism, as is the case with peristaltic pumps, there can be a minimum of problems associated with "memory" of the resilient material In some of these embodiments, a telescoping screw having two or more coaxial, nested screws can be used. As the solution is displaced from a solution reservoir, the telescoping screw can be . extended, thereby permitting continued delivery of solution to the patient. Embodiments of this type of mechanism can include cams and slots whereby a cam of an inner screw can reversibly engage a slot in an adjacent outer screw. As used herein the term "cam" is equivalent to the term "pawl," which is a driving link or holding link of a ratchet mechanism that permits motion in one direction only.

At the time of implantation, the telescoping screw is in a "retracted" configuration, with all the nested screws being retracted into each other. Upon actuation of the pump, one of the nested screws is rotated, thereby driving a piston within a barrel away from motor 140, and thereby delivering an infusion into a tube or catheter attached to the end of the barrel. When the first nested screw has been extended fully, one or more cams become engaged with corresponding slot(s) in the adjacent outer screw, thereby rotating the outer screw. Similarly, when the outer screw has reached its fullest extension, a cam in the outer screw engages a slot in an "outermost" screw, thereby transferring rotational force to the outermost screw. In such a fashion, the infusion can be delivered from a device that requires only a fraction of the total length of a piston-type actuator not having the nested, telescoping screw. One advantage of certain pumps of this invention is reduced power consumption. With any implantable electronic device, one of the limiting factors in the life of the implant is loss of stored electrical energy. Prior art devices may keep their internal circuitry activated or active even during times during which the pump is not delivering solution. To overcome this problem, pumps of this invention may have microprocessors that are put into a low power mode. Then, upon instructions being given to the pump by a practitioner, the microprocessor can be reset into a higher power mode, and the pump activated. Thus, with the use of periods of low power operation, the useful lifetime of a battery can be increased and the need to surgically intervene can be reduced.

Other embodiments include electronic elements that control pump processes with a minimum consumption of power. In some of these embodiments, electronic components are in standby mode, and are activated upon receiving an interrupt signal from a supervisory personal computer ("PC") or real-time clock. Thus, for most of the time the pump is within the patient's body, very little power is consumed.

Certain embodiments of this invention are able to deliver an infusion with a desired controlled rate. In some embodiments, the delivery of an infusion may have a ramp shaped function. In others, the delivery may be by way of a square wave- shaped function. Other embodiments have radio-frequency (RF) controlled elements responsive to signals delivered from outside the patient. Using RF elements, the practitioner can provide instructions to the pump mechanism to alter (e.g., start, stop, or vary) the rate of infusion being delivered to the patient. Software and hardware elements are provided to accomplish these objectives.

DETAILED DESCRIPTION Overview

In certain embodiments, pumps of this invention are small, implantable devices made of biocompatible materials known in the art. Such pumps have a small micro controlled battery powered mechanism, which uses a linear telescoping actuator with a high-precision positioning system. The positioning system permits the accurate and highly controlled delivery of a solution contained within a reservoir holding a solution for infusion. One end of the drug reservoir is attached to a delivery catheter, made of biologically compatible material known in the art. Within the drug reservoir, a piston-type plunger is fitted with a resilient seal that minimizes or prevents leakage of the infusion solution out of the reservoir and behind the plunger.

An actuator is attached to the plunger with a novel nested, telescoping screw mechanism described herein below. The actuator is operably linked to an electronic motor that rotates one or more screws to apply pressure to the reservoir, thereby urging the solution out of the reservoir, through the catheter and into the desired location within a subject.

The motor is operably linked to a processor that can receive instructions from software within the pump, or contained in an external device, operated by a physician or other health care professional.

Instructions can be received by the pump using RF signals transmitted by the external device, under control of the practitioner. A supervisory controller (e.g., computer) can run a "front end" interface software program that enables setting of different pump parameters associated with the infusion process. A micro Electronically Erasable Programmable Read-Only Memory (EEPROM) memory device can store desired variables (e.g., dose per infusion, interval between doses, concentration of a drug, infusion rate, infusion rate change, and the like). In certain embodiments, the infusion process can be accompanied by monitoring the pressure in the reservoir using a small pressure transducer. Such monitoring can permit detection of obstructions of the catheter. If the pressure is above a certain, preset threshold, the infusion can be stopped and the catheter cleared.

In other embodiments, the position of the plunger can be monitored using a probe at the motor end or by a linear variable displacement transducer ("LVDT") transducer inserted in the pump. A catheter attached to the outflow end of the reservoir can be of any desired length. Typically, the pump body may be positioned in the thoracic or abdominal region, typically subcutaneously. The catheter tip can be positioned in any desired location. For certain uses of pumps of this invention, the catheter tip can be placed in a region of the brain or other organ into which the solution is to be infused. To reach the central nervous system, the catheter can be extended from the pump into the neck, at a convenient subcutaneous position, and then follow a convenient pathway to a desired portion of the brain or other organ. In some embodiments, the pump can be used to deliver neuroactive agents to the brain or other neural tissue or organ. In some of these embodiments, a neuroprotective compound may be used to decrease the adverse effects of disorders that can result in neurodegeneration. It can be appreciated that pumps of this invention can be used to deliver any of a wide variety of drugs to any desired organ, tissue or body part desired.

Pumps of this invention can include specially designed software programs to control the position of the actuator. In some embodiments, an acceleration profile may have a trapezoidal shape, with onset of infusion being very slow, and as time progresses, the rate of infusion can increase up to a constant flow rate. At the end of the infusion period, a trapezoidal shape of reduced flow can be useful to minimize large pressure changes from damaging the pump, catheter, or patient. A microcontroller onboard the pump can generate a motion profile in the form of pulses to be delivered to the motor drive board, which can be another module, integrated on board the pump to drive the motor (e.g., brushless or brushed direct current (DC) or stepper motor).

It can be desirable to minimize the power consumption of the pump. Power consumption can be minimized by sending the pump into "sleep mode" when not injecting. When an infusion is desired, a time controlled signal can be generated by an internal timing circuitry.

In certain embodiments, the response of a pump to external commands from the supervisory controller/programmer or the response to the internal real-time clock can be interrupt driven. A reason for using interrupt-driven control is that the pump microcontroller is sent into sleep mode when not injecting the solution. When a command is provided, an interrupt signal is received at the microcontroller interrupt pin, capable of activating the microcontroller. Such an "interrupt service" routine can keep power consumption minimized, and can turn all other electronic elements "off," thereby further reducing power consumption. When an "interrupt" signal is received, electronic elements can be activated. Additionally, the number of times in a given period may be limited, for example, to two (2) cycles per day, to further conserve battery power. Using this type of control, much of the time, the pump is "off' and little, if any power is used. However, when desired, the pump can be turned "on" to provide the desired infusion.

In this way, a period of therapy may be 2-3 months in duration, without having to re-energize the onboard battery. Further, using this type of "interrupt driven" control, the size of the pump may be decreased further, making it possible to implant pumps of this invention into patients of small size (e.g., children or even babies). Figure 1 depicts a block diagram of a pump 100 of this invention. Housing 102 has real-time clock 104, RF communication module 108, microcontroller 112, which has CPU 116, random access memory (RAM) 120 and EEPROM 124 therein. In some embodiments, RAM 120 can be located internal to CPU 116, and in other embodiments RAM 120 can be located external to CPU 116. Similarly, in some embodiments, EEPROM 124 can be located internal to CPU 116, and in other embodiments EEPROM 124 can be located external to CPU 124. Battery and power module 128, pump driving module 132, pump motor 140 and gearhead 144 are also within housing 102. Battery and power module 128 is operably linked to real-time clock 104, RF communication module 108, pump driving module 132 and microcontroller 112, to provide electrical power to those elements. PC or handheld programmer 136 is depicted nearby and in RF communication with RF communication module 108.

Description of Pump Components

Figure 2 depicts a schematic diagram of a power supply of a pump 200 of this invention. As in Figure 1, real time clock 104 and CPU 116 are shown operably connected to power supply 204, which contains two elements, a general power supply 208, which provides power to electronic elements of the pump, and a motor power supply 212, which provides power to the motor drive module 224. Batteries 216 and 218 provide a source of electric power to power supply 204. Electric power is also supplied to RF module and RF detection electronics 220 and to pressure measurement circuitry 228a and position measurement circuitry 228b.

Power supply 204 uses the voltage (e.g., 6 — 12V DC) from batteries 216 and 218 and converts the voltage to two lower voltages by switching or pulse width modulation (PWM). One voltage is supplied by motor power supply 212 and one voltage is supplied by general power supply 208, which supports other electronic elements. Motor power supply 212 may be variable and can, for example, have values in the range of about 3.2 V to about 5 V DC. General power supply 208 can provide any suitable voltage, for example, about 3.2 V DC.

Figure 3 depicts a block diagram of a CPU 300 for use in a pump of this invention. CPU 300 is a microcontroller module that synchronizes the operations of the pump and communicates with the different electronic modules. General power supply 208 provides power to real-time clock 104, RF module 321, RF detector 322, field effect transistor (FET) switches 326 and 330, pressure measurement circuitry 228a, position measurement circuitry 228b, and to CPU 116, which in the depicted embodiment comprises RAM & flash RAM element 334 and EEPROM 338. Motor power supply 212 is shown connected to motor drive module 224. CPU 116 reads the program stored in flash RAM memory 334 and executes the instructions and stores output parameter values in EEPROM 338. Parameters stored in EEPROM 338 can control the operation of the pump, such as volume of solution to be infused and the interval of time between doses. CPU 116 also performs data logging functions, such as saving the number of times the pump communicates with PC or handheld programmer device 136 of Figure 1 over the RF link (telemetry). CPU 116 can also measure pressure in the catheter via pressure measurement circuitry 228a. This pressure can be diagnostic of operation of the pump and obstructions of the catheter.

CPU 116 can also process communication data through RF module 321 and RF detector 322 to respond to incoming messages and commands. CPU 116 can also process dose information and can convert data stored in EEPROM 338 to the required number of pulses to drive motor drive module 224. CPU 116 synchronizes operation of motor drive module 224. CPU 116 also acquires and stores data from pressure measurement circuitry 228a and position measurement circuitry 228b, and processes these values, thereby generating a pressure index and position index, which are stored in EEPROM 338. CPU 116 also sets real-time clock module 104 according to data received from RF module 321 and RF detector 322 to set the interval between doses. CPU 116 also controls power usage. When the pump is not in use, field effect transistor (FET) switches 326 and 330 are set to "off" states, thereby disconnecting power modules from the pump circuitry and electronics.

RF Module and RF Detector

Figure 4 depicts a block diagram of a communications system 400 between the implanted pump and external controller of this invention (external PC or programmer). RF module 321 is operably linked to RF antenna 404. RF detector 322 is operably linked to RF antenna 408. RF detector 322 is operably linked to a transmission line and is continuously powered by power supply (not shown). RF module 321 is turned on only when the pump needs to be in communication with the external PC or programmer, so the supply to RF module 321 is controlled by the FET switch (not shown). RF module 321 is an RF serial communication link that is adapted to transfer data between the pump and the external PC or programmer. RF detector 322 is a receiver block powered continuously by the general power supply (not shown). RF detector consumes very low power (e.g., nanoamperes). The low power consumption of RF detector 322 is sufficient to maintain the RF system to remain on standby continuously unless an interrupt signal is generated by RF detector due to RF reception at the antenna 408, at which time the pump is switched out of standby mode.

Real-Time Clock

Figure 5 is a block diagram of real-time clock 500 for use in a pump of this invention. To infuse a drug at precise and accurately timed intervals, an accurate device for measuring time is needed. Such a device is shown in Figure 5. CPU 116 is operably linked to real time clock 104. Signals from real-time clock 104 coordinate and provide time indices to interrupt logic and flags module 504. When an interrupt signal is generated by Real-Time Clock 104, an interrupt message 508 is sent to CPU 116. Interrupt changes the mode of operation of CPU 116 from standby (sleep mode) to active mode where CPU 116 executes a subroutine for infusing the dose of drug- containing solution. CPU 116 reads dose information stored in EEPROM (not shown) and converts that information into a number of pulses to the motor to infuse the correct volume of drug-containing solution. In some embodiments, real-time clock 104 is a crystal-controlled device.

The interrupt generated by CPU 116 overrides that of the RF module (not shown) so that the dose of drug will be infused first, and then a response is made to an incoming message from the PC or programmer (not shown).

Motor Drive Module

An electronic motor drive module is used to control the position of the motor that injects the drug. Figure 6 depicts a block diagram of a motor drive module 600 for use in a pump of this invention. CPU 116 is operably linked to motor drive module 224, which is operably connected to motor 140. Motor 140 is mechanically linked to gearhead 144, which is connected to actuator 604, which is connected to a piston-type plunger within a solution reservoir (not shown). Actuator 604 may include a telescoping screw (not shown in this diagram; see below). CPU 116 generates signals that are sent to motor drive 224 to drive motor 140 by the number of pulses desired. Motor drive 224 also supplies commutation pulses to motor 140 to control the direction of rotation of actuator 604. Motor 140 may include a position-measuring device (e.g., a hall probe or LVDT, not shown) to provide position feedback to CPU 116. Motor drive module 224 is generally activated only when drug-containing solution is being infused. Otherwise, motor drive module 224 remains in standby mode to conserve power.

Pressure and Position Sensors To verify correct operation of a pump after delivery of each dose of infused drug, pressure within the system is monitored. Figure 7 depicts, a diagram of a pressure and position sensor block 700 for use in a pump according to this invention. CPU 116 is operably linked to both pressure measurement circuitry 228a and position measurement circuitry 228b. Pressure measurement circuitry 228a is operably linked to pressure sensor 704. Position measurement circuitry 228b is operably linked to position sensor 708. Pressure measured by pressure sensor 704 is compared to a value stored in a look up table in the EEPROM 338. If the pressure value stored in EEPROM 338 is different from that sensed by pressure sensor 704 after infusion has ceased, a signal is generated that alerts the PC or programmer (not shown) to a possible blockage of the catheter. Linear position of the pump actuator is provided by position sensor 708. Position sensor 708 provides a signal to CPU 116. Position measured by position sensor 708 is compared to a value stored in a lookup table in EEPROM 338. If the position value stored in EEPROM 338 is different from that sensed by position sensor 708, a drive signal is produced, which is transmitted to motor 140 as depicted in Figure 1. Position sensor 708 may be a linear differential transformer or a Hall probe. As with other components of the system, when not in use the pressure and linear position module is set to standby mode to conserve power.

Linear Actuator To closely control the amount of drug-containing solution delivered to a patient, a linear actuator and solution reservoir system is used. Figure 8 depicts a cutaway drawing of an embodiment 800 of a portion of a pump according to this invention. As used herein, the term "proximal" refers to a position relatively near to or in the direction towards motor 140. The term "distal" refers to a position relatively farther from or in the direction away from motor 140. Barrel 804 is depicted having a cylindrical body with a reservoir 806, containing a solution having the desired drug(s) stored therein. At the distal end, a connector 808 is adapted to receive a catheter (not shown). Connector 808 may be a Luer-Lock™ type of connector or other type known in the art. The proximal end of reservoir 806 is defined by plunger top 814 having a face 812. Because a vacuum is created behind plunger top 814 when plunger top 814 is moved forward, a pressure source can be present at the back of plunger top 814 to compensate for the vacuum. It can be desirable to include a fluid behind plunger top 814. To create the source of pressure, one embodiment of the invention contains a biocompatible inert gas under pressure (not shown) and a pressure-regulating valve attached to the wall of the reservoir (not shown). Leakage of solution or gas in either direction around plunger top 814 is minimized by seal 816. In an alternative embodiment, leakage of solution or gas in either direction around plunger top 814 is minimized by multiple parallel seal rings (not shown) located around the plunger. Seals may be made of a resilient material such as silastic or other polymer. Plunger top 814 is moved linearly along the axis of reservoir 806 by linear actuator 820.

Linear actuator 820 is driven by gearhead 144, which is, in turn, driven by motor 140.

Figure 9 depicts a longitudinal cut-away diagram of a portion of linear actuator 820 of an embodiment of a pump according to this invention. Barrel 804, reservoir 806 and connector 808 are shown as in Figure 8. Figure 9 depicts an embodiment, similar to that depicted in Figure 8. Plunger body 922 in this embodiment is covered by seal 917.

Turning to the enlarged portion of Figure 9, an embodiment of a linear actuator is presented at or near an early stage of delivery of drug (i.e., a "retracted" position). Seal 917 surrounds nut 924, which is fixed to plunger body 922. Nut 924 is internally threaded by threads on the inner aspect of coaxial element 926. Seal 917 and nut 924 can move linearly and coaxially within barrel 804. In some embodiments, seal 917, plunger body 922 and nut 924 may be prevented from rotating within barrel 804 by means of a slot and cam type of mechanism (not shown) or other means known in the art. Outer screw 928 is depicted within nut 924. Outer screw 928 is threaded externally in a fashion to engage internal threads of nut 924. Outer screw 928 is also internally threaded. Inner screw 932 is threaded so as to engage with the internal threads of outer screw 928. Inner screw 932 is attached to shaft 936, which is attached to gearhead 144, which is attached to motor 140 (not shown).

When motor 140 (not shown) rotates, shaft 936 rotates, and thereby rotates inner screw 932. The rotation of motor 140 (not shown) and the direction of threads on inner screw 932 are selected so that with rotation, the inner screw moves the outer screw distally along the axis of barrel 804, thereby urging nut 924 away from motor 140. For example, if inner screw 932 has "right hand" threads, when viewed from the distal end of the screw (i.e., the end opposite from the motor), a clockwise rotation of inner screw 932 will urge outer screw 928 to the right (e.g., "unscrew" outer screw 928). This will in turn dispense solution out of reservoir 806, which is defined by plunger top 914 having a face 912. In other embodiments, inner screw has "left hand" threads. In these embodiments, rotation of inner screw 932 in the counterclockwise direction will urge outer screw 928 to the right, thereby dispensing solution from reservoir 806. The motor drive electronics (not shown) translates the number of pulses supplied by the microcontroller into another set of synchronized pulses that result in rotating the motor by number of revolutions or fraction of a revolution, a process herein called "commutation."

When inner screw 932 has urged outer screw 928 to its maximal linear displacement ("extended position"), a stop mechanism (not shown) prevents disengagement of inner screw 932 from outer screw 928. Such a stop may be a simple flange to prevent further linear motion. In other embodiments a stop mechanism may comprise one or more cams, or pawls, on inner screw 932 and corresponding slots on outer screw 928 (see Figure 10 below for details). Once inner screw 932 has reached its maximal linear extension relative to outer screw 928, then inner screw 932 engages with outer screw 928 and further rotation of shaft 936 and inner screw 932 rotates outer screw 928 in the same direction. Threads on the outer aspect of outer screw 928 engage threads on the inner aspect of coaxial element 926. As outer screw 928 rotates, threads on screw 928 urge coaxial element 926 and nut 924 in a linear fashion, extending plunger top 914 distally, thereby dispensing solution from reservoir 806.

It can be appreciated that this type of nested telescoping linear actuator may have a single outer screw (as shown in Figure 9) or may have a plurality of screws, each coaxially nested and threadably engaged with its neighbors. In some embodiments, linear actuators have two screws; in other embodiments, a linear actuator can have three screws. In other embodiments, a linear actuator may have four or more coaxially nested screws.

One benefit of the nested, coaxial linear actuators of pumps according to this invention is that the size of the implanted pump may be minimized in the retracted state, while the actuators can provide a total linear displacement substantially greater than the retracted length of the actuator. It can be appreciated that with larger numbers of nested screws, the pump can be shorter in length. Additionally, it can be appreciated that one can select a barrel having a diameter and length chosen to fit into a particularly sized patient or location within a patient's body.

Figures 10a — 1Od depict a "cam and slot" locking mechanism employing, as an example, two elements according to embodiments of the invention, enabling inner screw 932 to drive outer screw 928. Figures 1Oe — 1Oh depict a "cam and slot" locking mechanism employing, as an example, three elements according to embodiments of the invention, enabling inner screw 932 to drive outer screw 928. Any number of elements may be used, as will be evident to those of skill in the art.

Figure 10a depicts an oblique view of telescoping, two-coaxial, threaded screws of an infusion pump according to this invention, depicting inner screw 932 fully retracted within outer screw 928. Cams 1004 may be spring-loaded and are arranged to engage slots 1008 when inner screw 932 reaches its maximal linear extension with respect to outer screw 928.

Figures 10b- 10c depict cross-sections of an embodiment of a locking mechanism for use in a pump according to this invention. In Figure 10b, maximal linear displacement of inner screw 932 relative to outer screw 928 has not been reached, and thus, cams 1004 of an inner thread are unlatched from slots 1008 in an outer thread. However, cams 1004 are urged centrifugally using springs (not shown) located beneath the cams 1004 against the inner aspect of outer screw 928, so that when the maximal linear displacement position ("latched position") is reached in Figure 10c, cams 1004 of an inner thread engage slots 1008 in an outer thread and the stopper 1006 secures cams in their position in the slots 1008. Cams 1004 are positioned such that when slots 1008 are in the proper position, cams 1004 fit within slots 1008 (Figure 10c), thus stopping further clockwise rotation of inner screw 932 with respect to outer screw 928. Figure 1 Od depicts a perspective view of telescoping, two-coaxial, threaded screws of an implantable infusion pump according to this invention, depicting inner screw 932 and outer screw 928. Cam 1004 is arranged to engage slot 1008 when inner screw 932 reaches its maximal linear displacement with respect to outer screw 928.

Figure 1Oe depicts an oblique view of telescoping, three-coaxial, threaded screws of an implantable infusion pump according to this invention, depicting inner screw 932, outer screw 928 and nut 924. Inner cams 1010 may be spring-loaded and are arranged to engage inner slots 1012 when inner screw 932 reaches its maximal linear extension with respect to outer screw 928. Similarly, outer cams 1014 may be spring-loaded and are arranged to engage outer slots 1016 when outer screw 928 reaches its maximal linear extension with respect to nut 924.

Figures lOf-lOg depict cross-sections of an embodiment of a locking mechanism for use in a pump according to this invention. In Figure 1Of, maximal linear extension of inner screw 932 relative to outer screw 928 has not been reached, and thus, inner cams 1010 of an inner thread are not aligned with inner slots 1012 in an outer screw. However, inner cams 1010 are urged centrifugally by springs (not shown) located below inner cams 1010 against the inner aspect of outer screw 928, so that when the maximal linear extension position ("latched position") is reached, inner cams 1010 engage inner slots 1012 and are secured into position by inner stoppers 1018. Similarly, maximal linear extension of outer screw 928 relative to nut 924 has not been reached, and thus, outer cams 1014 of an outer thread are not aligned with outer slots 1016 of a nut 924. However, outer cams 1014 are urged centrifugally by outer springs (not shown) located below cams 1014 against the inner aspect of nut 924, so that when the maximal linear extension position ("latched position") is reached, outer cams 1014 engage outer slots 1016 and are secured into position by outer stoppers 1020. Inner cams 1010 are positioned such that when inner slots 1012 are in the proper position, inner cams 1010 fit within inner slots 1012 (Figure 1Og), thus stopping further clockwise rotation of inner screw 932 with respect to outer screw 928. Similarly, outer cams 1014 are positioned such that when outer slots 1016 are in the proper position, outer cams 1014 fit within outer slots 1016, stopping further clockwise rotation of outer screw 928 with respect to nut 924.

Figure 1Oh depicts a perspective view of telescoping, three-coaxial, threaded screws of an implantable infusion pump according to this invention, depicting inner screw 932 outer screw 928, and nut 924. Inner cams 1010 are arranged to engage inner slots 1012 when inner screw 932 reaches its maximal linear displacement with respect to outer screw 928. Similarly, outer cams 1014 are arranged to engage outer slots 1016 when outer screw 928 reaches its maximal linear displacement with respect to nut 924.

Pump Software

Software operation of pumps of this invention is based on a number of different parameters that are stored in EEPROM of the microcontroller. The pump can access these parameters before injecting the dose of drug and will update the parameters and store them in EEPROM. Certain values can be stored in non-volatile memory and therefore remain unchanged during operation, and even in the event of power loss. Further, when the pump electronics are active, non-volatile memory elements can be accessed and loaded into buffer storage in the CPU. Certain parameters determine the dose of drug to be delivered per unit time, the interval between doses during which the pump is in standby mode as well as access information (password) used to communicate with the pump via external PC or programmer.

During injection of a dose, a number of parameters are typically recorded and stored in the EEPROM for future use. Examples of such parameters include maximum pressure within the reservoir, linear position of the plunger and bolus number. These parameters can be accessed at random via the external PC or programmer, to provide ongoing information to the practitioner.

To facilitate the design of software, the above (and/or other) parameters are given codes or names, which the supervisory software and the microcontroller onboard the pump can use to access the information stored in the EEPROM. Table 1 below shows an example of such a list of names.

Table 1 Pump Parameters

Modify P A S S W O R D ! M Mooddiiffyy S S L L E E E E P P !

Modify D O S E ;

Read I N D E X 9

Read V O L I N D E X ?

Read L I N D E X 9 Read P R I N D X ?

Read S L E E P ?

Read D O S E ?

Communications with the pump is effected via .an RF link to provide telemetry. When an attempt is made to communicate with the pump, a password is requested by the pump. Each pump can have .a unique password. If the password entered by the user is correctly recognized, then access to the pump is granted. The pump will then respond to commands given. The parameters are described as follows.

PASSWORD ! (to update password)

This parameter is a request from the supervisory PC to update the access password to the pump. In some embodiments, a 6-letter word can be used. A microcontroller in the pump can store the new password in the EEPROM. The PC will transmit the old password to trigger a request to update to a new one. SLEEP ! (to update interval between doses)

This parameter determines the sleep period (standby period) of the pump. To update the sleep period, the new parameter will be stored in the microcontroller's EEPROM. The microcontroller should refer to this EEPROM' s location before going to sleep to get the exact amount of time. SLEEP! Will write a new value in this location in the EEPROM. Sleep will change setting of the real-time clock to determine when the pump should next wake up (i.e., setting the time to activate the pump for the next operation).

DOSE ! (to update the dose in microliters) This parameter determines the amount of the solution to be infused (in microliters) per dose. This command will write a new value into the EEPROM. The value represents the number of pulses from the CPU to the motor controller. The above parameter is subdivided into three sub-parameters as follows (each with their own location in EEPROM). l. Dose,

2. Acceleration parameter,

3. Deceleration parameter

INDEX ? (number of times the pump has injected drug) This is a read-only parameter. It instructs the supervisory PC how many doses of solution have been delivered before the command is given. This is used to keep track of the total number of doses delivered.

VOLINDEX ? (voltage index) This parameter monitors the voltage of the battery onboard the pump after each delivery. This parameter is set according to the specifications of the drug the pump will dispense for a typical 90-day infusion period. For example, there may be 90 EEPROM locations allocated for this parameter. When a request is made by the supervisory PC or programmer to read the voltage, the delivery index has to be specified to record the voltage at this particular index. LINDEX (linear index)

This parameter is used to record the linear distance traveled by the pump actuator before a request is made by the supervisory PC to monitor this distance.

PRINDEX ? (pressure index) This parameter is monitored after each delivery, and reflects the maximum pressure reached after each delivery of drug. The purpose of measuring and storing this information is to evaluate pump performance while in use. Like the voltage parameter above, pressure data is allocated sufficient space (e.g., 90 days) in EEPROM to be accessed by the supervisory PC. SLEEP ? (time interval between doses)

This parameter represents the time interval between delivery of successive doses of drug. The PC will read the contents of the corresponding EEPROM location. DOSE ? (dose to be delivered)

This parameter reads the dose of the drug to be injected per delivery period. This is a read-only parameter.

The supervisory software represents the front-end interface for clinicians or other practitioners to set the pump or to read its parameters for follow up purposes. When the parameters are set in the supervisory software (e.g., using a graphic user interface or GUI), data processing occurs before the parameters can be converted to digital format to be transmitted to the pump via the RF link. Such pre-processing of data in the supervisory PC can reduce the processing burden on the microcontroller, whose operation can be dedicated to monitoring the delivery process and pump function as well as performing housekeeping commands to control other electronic modules on board the pump. Operation of the software is further described in Figures l la and 1 Ib. Figure 11a depicts a flow chart 1100 of software processing by a pump of this invention. After Start 1104, default parameters are set at step 1108, including password, sleep interval and dose. At step 1112, linear and pressure indexes are reset. At step 1116, the system is in state A. At step 1120, the system goes to sleep state. At step 1124, it is queried whether an interrupt is provided by a real-time clock. If no such interrupt signal has been received from the real-time clock, at step 1128, it is queried whether an interrupt is provided by the supervisory PC. If no such interrupt is received from the supervisory PC, at step 1120, the system goes to sleep state. Alternatively, if at step 1128, it is noted that an interrupt has been received from the supervisory PC, then the system proceeds to step 1136, where the system reads a password. At step 1140, the system evaluates the correctness of the password entry. If at step 1140, the password is evaluated as incorrect, the software goes to sleep state at step 1120. Alternatively, if at step 1140, the password is evaluated as correct, then the system proceeds to step 1148, where it processes commands for INDEX, VOLINDEX, PRINDEX, SLEEP and DOSE. Then the system branches to B at step 1150. Alternatively, if it is noted at step 1124 that the real-time clock has initiated an interrupt, then the system reads the dose from the EEPROM at step 1132. The system then turns on motor drive, pressure transducer and linear transducer at step 1144. Then the system branches to state C at step 1146.

Figure l ib depicts a continuation of the flow chart shown in Figure l la. From state B in step 1150, the pump proceeds to step 1152, at which it responds to commands, reads existing parameters from the EEPROM and updates parameter values. When these actions are completed, the system branches to state A at step 1116 where the system goes into sleep state at step 1120. Alternatively, if the system is at state C in step 1146, the system proceeds to step 1160, where it delivers a drug, reads maximum pressure after delivery and destination position. At step 1164, the system then compares the maximum pressure detected to the pressure in the lookup table for the relevant dose. At step 1170, it is determined whether the pressure is acceptable. If at step 1170, the pressure is determined not to be acceptable, then at step 1174, the system reports an emergency to a supervisory PC or programmer. Then the software branches to state A at step 1116 where the system goes into sleep state 1120. Alternatively, at step 1170, if the pressure is determined to be acceptable, then at step 1182, the system records pressure, battery voltage, and new position in the EEPROM. When these actions are completed, at step 1184, the motor drive, pressure transducer and linear transducer are turned off. Then the software branches to state A at step 1116, where the system goes into sleep state 1120.

Alternative Drug Reservoirs

The embodiments of drug reservoirs described above depict a cylindrical syringe-type device having a circular cross-section. However, other shapes of devices can be used. Figures 12a — 12c depict three exemplary alternatives. Each of the alternatives described below has advantages. Compared to a cylindrical barrel having a circular cross-section, for a given length of reservoir, a greater volume of solution can be stored in the ellipsoid drug reservoir (e.g., Figure 12a). Thus, one can provide implantable pumps having a larger stored volume of solution, thereby permitting a longer interval between surgical procedures needed to re-fill the drug reservoir.

Additionally, in one embodiment (Figure 12c), the barrel can be contoured to fit more conveniently into a patient's body (see below).

Figure 12a depicts a cross-section view of embodiment 1200a of this invention, wherein drug reservoir 1204 is defined by barrel 1208 having an ellipsoidal cross-section.

Figure 12b depicts a cross-section view of embodiment 1200b of this invention, wherein drug reservoir 1210 is defined by barrel 1214 having a rectangular cross-section.

Figure 12c depicts a cross-section view of embodiment 1200c of this invention, wherein drug reservoir 1218 is defined by barrel 1222 having a contoured cross-section. One advantage of this type of embodiment is that a comparatively large volume of solution can be stored in the drug reservoir 1218 for a given length of the barrel. Further, a contoured shape can permit the pump barrel to fit more conveniently within the body of the patient. For example, if the pump is to be placed under the skin over the rib cage, the contoured shape of the barrel can permit the pump to be less obtrusive. It can be appreciated that the above or other shapes of barrels and of reservoirs may be housed in a pump body of any desired shape, and in some embodiments, the pump body can have rounded corners to be biologically compatible. Pump Configurations

It can be appreciated that pumps of this invention can be contained within a housing of any desired shape. For example, to decrease tissue damage, pumps, pump barrels, catheters and other equipment can have rounded surfaces. Further, pump electronics and barrels can be contoured to fit conveniently in a desired location in the patient's body. For example, if a pump is implanted over the rib cage, the pump mechanism can be housed in a contoured casing having a cross-section similar to that of the barrel in Figure 12c.

High-Level Software for Dose Infusion

We have developed new software to infuse a precise dose of drug and maintain accuracy of dosage throughout the treatment. The flowcharts are set out in Figures 13a and 13b. In order to reduce the processing burden on the pump CPU, motor rotation required for administration of a selected dose and the acceleration and deceleration parameters are pre-calculated by the high level software in the PC or external programmer. These calculations are made in the front-end high-level software and are invisible to the clinician or health practitioner who sets up the pump. The clinician is only required to specify a dose to be infused and the remaining mechanical calculations are handled by the front-end software automatically. Figure 13a depicts a software flowchart 1300 for a high-level program used to compute the dose to be administered through the pump.

Pre-calculated results are then sent to the pump via RF in the form of parameters to be stored in the EEPROM onboard the pump. This approach allows us more flexibility in selecting a general purpose CPU for the pump, as there is no need for a very powerful microcontroller or CPU to control the pump. Powerful CPUs, usually used in the implantable devices, need relatively higher power consumption which would reduce stored electrical energy of the pump and result in shorter therapy periods.

The high-level software depicted in Figure 13a performs the following tasks: 1. Verifies dose of drug, in microliters, to be infused per bolus;

2. Sends the number of dose microliters to be infused as a parameter to the pump;

3. Converts the number of dose microliters per dose into number of pulses made by CPU software to operate the motor; 4. Calculates acceleration and deceleration constants (MN, MX) for the required dosing, where MN is the number of pulses at which acceleration of the motor stops and MX is the number of pulses at which deceleration of the motor begins. 5. Sends the above four parameters (number of dose microliters Xμl, number of drug-infusing pulses Y, MN, MX) to the pump via RF link, to ensure that the right acceleration/deceleration profile is achieved, making infusion highly accurate.

Pulse calculation

The number of CPU pulses to be supplied to motor drive unit in order to administer a requested dose is calculated as follows and illustrated in Figure 13a.

After start 1304, in step 1312, the number of dose microliters (Xμl; parameter 1) is entered. In step 1316, the number of dose microliters (Xμl) is converted to a total number of pulses (N) for one revolution of the motor unit. The value of N depends on the gear ratio and the number of commutation pulses required for one revolution. In step 1320, based on N, a number of required dose-infusing pulses Y is calculated. To calculate Y from N, total volume (V) displaced by syringe at one motor revolution must be calculated. The volume per cross section area of inside of the reservoir (A) is calculated in the following way:

equals the radius of the inside of the reservoir. The length of linear displacement of the actuator resulting from one full revolution of the motor (L) is retrieved. The total volume (V) is calculated in the following way: V= A x L. The number of pulses (Y) required to infuse the required dose of drug (D) is calculated in the following way: Y = N/Vx D. As an example, in one embodiment where N=3750 pulses; r=6.39mm, L=0.25 mm, D=I μl; V~32.069μl, the number of pulses required to infuse lμl of drug is computed to be Y=3750/32.069xl=l 16.9-117 pulses.

Acceleration/deceleration rate calculation In step 1324, acceleration and deceleration indexes are calculated as products of number of drug-infusing pulses (Y) and, respectively, acceleration and deceleration constants. In step 1328, MN (acceleration index) is calculated by multiplying the number of drug-infusing pulses (Y) by an acceleration constant equal to, as an example, aboutθ.266. MX (deceleration index) is calculated by multiplying the number of drug-infusing pulses (Y) by a deceleration constant equal to, as an example, about 0.733. Using the example from the paragraph above, the acceleration and deceleration indices for a dose of lμl will be:

MN=I l 7*0.266=31.122«31 pulses. MX=I 17*0.733=85.761«86 pulses.

For example, to infuse lμl of drug, in step 1332, the following four parameters are transmitted to the pump during setup phase:

1- dose Xμl = lμl.

2. Number of drug-infusing pulses Y =117 pulses; 3. MN (acceleration index)=31, i.e. acceleration of the motor ends at pulse count of

31;

4. MX (deceleration index)=86, i.e., deceleration of the motor starts at pulse count of

86 to infuse 1 microliter using a total number of drug-infusing pulses Y=I 17.

The parameters are stored in the allocated locations of EEPROM. The process ends in step 1336. It can be appreciated that the above calculated doses and amounts are for example only. Other amounts of solution to be delivered can be calculated using similar methods and are considered within the scope of this invention.

CPU Software for Motor Drive Figure 13b depicts a software flowchart 1338 for a micro-level program used to compute acceleration/deceleration parameters in dose administration through the pump. After start 1340, in step 1344, CPU-embedded software retrieves from EEPROM parameter values for dose in microliters, total number of drug-infusing pulses Y, MN, and MX. In step 1348, the CPU initiates a counter of the number of pulses i supplied to the motor drive during current infusion, i is initially set to 0 prior to initiation of the infusion. The CPU tracks the number of pulses infused to determine when the acceleration stops or deceleration begins. This process is done on the fly and works for any volume of dose to be infused thus it is always assured that the motor/actuator will travel the exact linear displacement required to infuse the exact dose requested.

In step 1352, pulse interval parameter J is calculated according to the formula, for example, J = 4000+MN. J is a parameter whose value equals the length in microseconds of the interval between pulses supplied to the motor drive. The value of J therefore controls the speed at which the infusion takes place.

We proceed to step 1356, also labelled (B) for branching, after which, in step 1358, i is incrementally increased to i+1 to reflect the new pulse that is being processed. In step 1360, the value of i is compared with acceleration index MN. If in step 1360, i is found to be less than MN, meaning that we are still in the acceleration phase of infusion, then in step 1364, pulse interval parameter J is incrementally decreased to J-I . Then in step 1368, the system branches to state A.

Alternatively, if in step 1360, i is not less than MN, meaning that we are beyond the acceleration phase of infusion, then in step 1372, pulse interval parameter

J is, for example, set equal to 4000. Then in step 1376, the value of i is compared with deceleration index MX to determine whether to start deceleration. If in step 1376, i is found to be greater than MX, meaning that we are in the deceleration phase of infusion, then in step 1380, pulse interval parameter J is incrementally increased to J+l . Then in step 1368, the system branches to state A.

Alternatively, if in step 1376, i is not found to be greater than nor equal to

MX, meaning that we are not in the deceleration phase of infusion, then the system enters into state. A in step 1368. In step 1384, a pulse is output to the motor drive. In step 1388, pulse interval parameter J determines the duration of the pulse to the motor drive. J therefore sets the frequency of pulses and hence the motor speed. A pulse is operationally defined as a transition in output from a relative low to a relative high and back to a relative low. In step 1392, the pulse provided to the motor drive ends. In step 1396, it is queried whether number of pulses supplied to motor drive during current infusion (i) equals the total number Y of drug-infusing pulses required. If the answer is determined to be no in step 1396, then in step 1356, the system branches to state B. Alternatively, if the answer is determined to be yes in step 1396, then the program ends in step 1398. The above program determines acceleration and deceleration profiles when infusing the drug and is, according to embodiments of the invention, integrated into the embedded software of the pump's CPU.

Infusion of Solutions

Drugs may be infused at any desired time interval, for example, 1 second, 5 seconds, 10 seconds, 20 seconds, 30 seconds, 1 minute, 2 minutes, 5 minutes, 10 minutes, up to about 1 hour. For drugs with long biological half-lives (Tl/2), the infusion may last for several seconds to several minutes to several hours, depending on the desired amount and rate of delivery of the drug. Then, the pump can be put into sleep mode until sufficient time has passed to warrant another infusion. If, for example, the Tl/2 of the drug is 18 hours, then 18 hours after the last infusion, the pump can be turned on to deliver another dose of drug.

Types of Drugs

The types of drugs that can be infused using pumps of this invention are not limited. For example, agents can be used for infusion into the brain, vascular system, an internal organ, or any desired location within the body. For uses for nervous system use, large peptides or proteins can be used. In particular, growth hormone (GH) can be delivered to the brains of patients to improve neural outcome following neurological damage or disease. In some embodiments, the GH is pituitary GH, and in other embodiments, the GH is placental variant GH, having reduced lactogenic effects as described in U.S. Patent No: 6,933,278, or U.S. Patent Application No: 10/643,450, publication No: US 2004/0096433 Al, both expressly incorporated herein fully by reference as if individually so incorporated. In addition, a 20- kilodalton version of GH can be used. Other peptides include (1) insulin-like growth factor 1 (IGF-I) as described in U.S. Patent Application No: 10/013,812, titled "Compositions and Methods for the Rescue of White Matter," filed December 7,

2001, herein expressly incorporated fully by reference; and (2) activin, as described in U.S. Application No: 10/177,735, titled "Methods of Providing Neuroprotection And/or Neurorestoration via the Neural Activin Type HB Receptor," filed June 20,

2002, herein expressly incorporated fully by reference. Additionally, other peptides can be used, such as those described in (3) U.S. Patent Application No: 10/225,838, titled "Neural Regeneration Peptides and Methods for Their Use in Treatment of Brain Damage," filed August 22, 2002 and (4) U.S. Application No: 10/976,699, titled "Neural Regeneration Peptides and Methods for Their Use in Treatment of Brain Damage," filed October 29, 2004, both applications incorporated expressly herein fully by reference.

In still further embodiments, a pump of this invention can be used to infuse a small-molecule neuroprotective agent. Such small neuroprotective agents include (5) the tripeptide Gly-Pro-Glu as described in U.S. Patent Nos.6,617,311, 6,682,753, 6,780,848, 6,812,208, 6,933,282; U.S. Patent Application No: 10/398,876, publication No: US 2004/0053850 Al, and (6) GPE analogs, including Glycyl-2-Methyl-L- Prolyl-L-Glutamic acid (G-2MePE) as described in U.S. Patent No. 7,041,314, cyclic Glycyl-2-Allyl Proline as described in U.S. Application No: 11/399,974, all incorporated herein expressly by reference in their entirety. Furthermore, other small molecule agents can be delivered, for example (7) bicyclic neuroprotective compounds, as described in PCT International Patent Application No: PCT/US2004/028308, titled "Neuroprotective Bicyclic Compounds and Methods for Their Use," filed 31 August 2004; and (8) macrocyclic neuroprotective compounds as disclosed in PCT International Patent Application No: PCT/US2004/08108, titled "Neuroprotective Macrocyclic Compounds and Methods for Their Use," filed 16 March 2004, both applications herein expressly incorporated fully by reference. Additionally, small molecule analogs of Neural Regeneration Peptides as described in U.S. Provisional Patent Application No: 60/772,947, filed February 14, 2006, Frank Sieg, inventor, titled "Synthetic Analogs of Neural Regeneration Peptides" herein incorporated fully by reference. Further, anti -epileptic drugs can be injected using pumps of this invention. Anti-epileptic drugs include sodium valproate, carbamazepine, gabapentin, lamotirgine, levetiracetam, oxacarbazepine, tiagabine, topiramate and vigabatrin.

It can be appreciated that in addition to methods for treating neurological disorders, this invention also includes pumps having reservoirs already prepared for implantation, including one or more drugs to be injected. Thus, in some embodiments, a pump can have a reservoir containing growth hormone, G-2MePE or any other single drug or combination of drugs listed above or known in the art.

It can also be appreciated that any desired agent can be delivered using pumps according to this invention. It can be appreciated that the embodiments described herein are intended for purposes of illustration only and are not intended to limit the scope of the invention. Other designs and modes of operation of pumps based on the disclosures herein can be contemplated and implemented without undue experimentation and with a reasonable likelihood of success. All such embodiments and their equivalents are considered to be part of this invention. All references cited herein are explicitly incorporated fully by reference as if they had individually been so incorporated.

Claims

Claims:

1. An implantable pump for infusion of a solution into the body of a patient, comprising: a pump actuator having a telescoping screw; a motor to control the screw; and a solution reservoir containing a solution having a drug therein.

2. The pump of claim 1 , further comprising a processor contains electronics that can receive RP signals from outside the patient to provide instructions to said processor.

3. The pump of claim 1 or 2, wherein said processor further includes software stored in memory to regulate delivery of said solution according to information stored in said memory.

4. The pump of any of claims 1 to 3, wherein said software includes an instruction to move said pump into standby mode after delivery of a pre-programmed volume of said solution to said patient.

5. The pump of any of claims 1 to 4, wherein a real-time clock signal provides an interrupt signal to move said pump out of standby mode, permitting said processor to control said motor to deliver a pre-programmed volume of said solution.

6. The pump of any of claims 1 to 5, wherein a radio frequency (RF) signal from external PC or a programmer enables setting parameters of the pump or downloading parameters of the pump.

7. The pump of any of claims 1 to 6, wherein said motor is operably linked to said telescoping screw, said screw comprising a plurality of co-axial members, one of said members being an internal member, and an outer member immediately adjacent to said internal member, said internal and outer members threadably engaged, so that when in a retracted configuration, rotation of said internal member urges said outer member linearly along said axis.

8. The pump of any of claims 1 to 7, wherein internal and outer members of said telescoping screw have a middle member threadably linked to said internal member and to said outer member.

9. The pump of any of claims 1 to 8, wherein in a retracted configuration, rotation of said inner member urges said middle member and said outer member linearly along said axis.

10. The pump of any of claims 1 to 9, wherein upon said inner member reaching its rotational limit, a cam or pawl engages with said middle member, so that upon further rotation of said motor, said middle member rotates, urging said outer member linearly along said axis.

11. The pump of any of claims 1 to 9, wherein upon said middle member reaching its rotational limit a cam or pawl engages with said outer member, so that upon further rotation of said motor, said middle member rotates, urging a co -axial nut linearly along said axis.

12. The pump of any of claims 1-11, further comprising a catheter for delivering said solution to a desired location in said patient's body.

13. The pump of any of claims 1-11, wherein said telescoping screw is operably linked to a plunger within a solution reservoir.

14. The pump of any of claims 1-11, further comprising a solution reservoir having a cross-sectional shape selected from circular, ellipsoidal, rectangular and contoured.

15. The pump of any of claims 1-14, further comprising: a processor having a program stored in memory, said program containing instructions for operating a motor, said instructions including an instruction for electronics of said pump moving into standby mode upon completion of delivery of a pre-determined volume of solution from a solution reservoir.

16. The pump of any of claims 1 to 15, further comprising a receiver of an interrupt signal, wherein said interrupt signal moves said pump electronics out of standby mode and initiates another delivery of a pre-determined volume of solution from said reservoir.

17. The pump of any of. claims 1 to 16, wherein said motor is operably linked to a telescoping screw, said screw operably linked to a nut, said nut operably linked to a plunger within said solution reservoir, whereupon activation of said motor, solution is dispensed from solution reservoir and into said patient.

' 18. The pump of any of claims 1 to 17, wherein said solution reservoir is operably linked to a catheter, said catheter having a tip located in a desired location within a patient's body.

19. A method of delivering a drug to a desired location within a patient's body, comprising:

(a) implanting an implantable pump of any of claims 1 to 17 into said patient's body, said tip of said catheter being located in a desired location, said pump having a solution reservoir containing a solution of a drug to be delivered; and

(b) initiating an RF signal to move said pump from standby to on mode.

20. The method of any of claims 1 to 19, wherein said drug is a protein, peptide or small molecule.

21. The method of any of claims 1 to 20, wherein said drug is a neuroprotective drug.

22. The method of any of claims 1 to 20, wherein said drug is an antiepileptic drug.

23. A method for determining a dose of drug for infusion, comprising:

(a) receiving from an operator an indication of a volume of solution containing a drug to be infused; (b) calculating a number Y of motor rotations of an infusion pump required for administration of said volume of drug;

(c) calculating an acceleration parameter representing the number of motor rotations for which rate of drug infusion is increasing; (d) calculating a deceleration parameter representing a number of motor rotations for which rate of drug infusion is decreasing; and

(e) transmitting to said pump said volume, said number Y, said acceleration parameter, and said deceleration parameter.

24. A method for operating a motor drive of a drug infusion pump, comprising:

(a) retrieving parameters for an infusion;

(b) initiating a counter of a number of pulses i supplied to the motor drive during current infusion;

(c) calculating a pulse interval parameter J; (d) decreasing J by 1 and then going to step (g) if i is less than an acceleration parameter;

(e) setting J equal to a pre-established constant if i is greater than or equal to said acceleration parameter;

(f) increasing J by 1 if i is greater than MX; (g) outputting a pulse to motor drive of duration J;

(h) going to step (d) if I does not equal the total number Y of required drug-infusing pulses; and

(i) ending the infusion if I equals Y.