Multiple Cartridge Dispensing System

(a) Field of the Invention

This invention relates to automated medication dispensing apparatus.

(b) Description of the Prior Art

Known automated dispensing devices, such as described in U.S. patent application Ser. No. 06/722,073, filed Apr. 11, 1985 and now issued as U.S. Pat. No. 4,674,652 offer reliable dispensing of medication that is stored in vials which are strip packaged. The information set forth in that patent is hereby incorporated herein by reference as is fully reproduced. It utilizes special storage volume designs in which the strip packaging is stored, and a sprocket drive mechanism that accommodates the special strip packaging. These features provide an extremely reliable dispensing device that is portable and can be operated in any positional orientation. However, as with most "first generation" devices, improvements can be made. Loading of th strip packaging into the first generation device requires that the strip packaging be fed into the storage volume and folded in a zig zag manner, and it dispenses only a single strip of vials.

The present invention provides a multiple cartridge dispensing system that improves on the "first generation" of such devices in several ways. These improvements are both mechanical and electronic. One of theses ways relates to the strip packaging of medication. The present invention provides an arrangement wherein the cartridge container for the strip packaging allows the strip packaging to be preloaded, preferably by mass loading machinery. The cartridges are specially dimensioned to preserve dispensing operation reliability. Preloaded cartridges can be stored for future rapid and simple loading into a more mechanically simple dispensing device housing.

The first generation dispenser also was designed to dispensing only one group of articles contained in a single strip package. However, there are many situations where a patient is on a regimen that includes taking two or more different types of medications at overlapping times. Therefore, another object of the present invention is to provide, in a single unit, for the dispensing of articles from more than one strip package.

This new generation of dispenser not only offers more compact dimensions when multiple strips are needed, but it also employs a unique dispensing control system that can dispense articles from the individual strips independently or coordinate the dispensing of multiple groups of articles. Whereas the first generation devices would require separate housings and drive mechanisms to dispense multiple strips, the present invention uses just one drive shaft and an unique clutch mechanism on the ejector elements to allow selective engagement. Another object of the present invention is to motorize the dispensing drive mechanism for improved reliability and ease of use by the infirm.

FIG. 1 is a perspective view of a dispensing unit 100 into which medication is loaded and from which it is dispensed to the patient.

FIG. 2 is a front view of an empty cartridge 200 into which medication can be loaded.

FIG. 3 is a side view of a cartridge 200.

FIG. 4 is a front view of an cartridge 200 loaded with a packaging strip 202.

FIG. 5 is a perspective view of dispensing unit 100 with the left side removed and the top flipped open.

FIG. 6 is a perspective view of the right side of dispensing unit 100.

FIG. 7 is a side view of ejector sprocket segment 130. All three ejector sprocket segments are the same, so only ejector sprocket segment 130 is shown.

FIG. 8 is a front view of ejector sprocket segment 130.

FIG. 9 shows drive shaft 342 as having a passages 356 therein.

FIG. 10 is a cut away side view of drive shaft 342 showing passages 356 associated with one of the ejector sprocket segments.

FIG. 11 is a cross section of ejector sprocket segment 130.

FIG. 12 is another cross section of ejector sprocket segment 130 showing the arrangement of spring loaded pin 360 in greater detail.

FIGS. 13, 14, 15, and 16 are a series of drawings showing the operation of an ejector at various points in time.

FIGS. 17 and 18 are cross sections showing locking pin 328 and its interaction with locking mechanism 330.

FIGS. 19(a) and 19(b) together form a block diagram of the microprocessor based dispenser electronic control system 326.

FIGS. 20(a) and 20(i b) together constitute a flowchart of the dispenser firmware.

FIG. 21 is a block diagram of the host system hardware.

FIGS. 22(a) and 22(b) together constitute a flow chart of the host system software which explains the interaction of the host system with the dispensing unit 100.

FIG. 23 is a graphical presentation of a compliance report prepared by the dispensing system according to the present invention.

The arrangement and functions of the multiple cartridge dispensing system according to the present invention are probably best described in terms of a specific medical dispensing application, even though the invention is not limited to such an application. At present, the preferred embodiment of the invention is utilized as a medication dispenser. The multiple cartridge dispensing system according to the invention helps patients take oral medications per a prescribed schedule and evaluates the patient's actual compliance to the regimen. Compliance is an indication of how closely the patient followed the prescribed schedule.

FIG. 1 is a perspective view of a dispensing unit 100 into which medication is loaded and from which it is dispensed to the patient. The multiple cartridge dispensing system according to the present invention includes dispensing unit 100 including software stored therein, a host computer (hardware block diagram shown in FIG. 21), host computer software (flow chart shown in FIGS. 22(a) and 22(b) and software listing in appendix), and an interface unit for coupling dispensing unit 100 to the host computer.

A drug therapist, usually a pharmacist or physician, loads dispensing unit 100 with medication containing cartridges. In FIG. 1, the left side of dispensing unit 100 is removed to reveal a cartridge cavity 102 into which medication loaded cartridges can be placed. The therapist then uses a host computer system to input dispensing schedules and instructions for each of the medications loaded. The host computer then transmits a computer language version of that information to the dispensing device. The prepared dispensing unit 100 (loaded with medication and schedule information) is then given to the patient to use.

During the medicating period, the patient is reminded both visually and audibly when a medication is due to be administered. Visual reminding is via a display 104 and audible reminding is via an alarm 106. Display 104 and alarm 106 are located on a lid portion 324 of dispensing unit 100. Access to any of the medications may be restricted to a specified period before and after prescribed dosing times so that inadvertent or intentional drug abuse is prevented. The patient is told which medication to dispense by messages appearing on display 104 which can display a scrolling alphanumeric message. When a patient is ready to dispense a medication, he simply pushes button "A" 110, button "B" 112, or button "C" 114 which are associated with three medication cartridges, respectively. Dispensing unit 100 operates either ejector 120, ejector 122, or ejector 124 to dispense a medication vial from just the selected cartridge and thereby dispense the proper medication. To operate ejector 120, a ejector sprocket segment 130 associated therewith is rotated. Similarly, to operate ejector 122, its ejector sprocket segment 132 is rotated and to operate ejector 124, its ejector sprocket segment 134 is rotated. The sprocket segments are rotated automatically after the associated button "A" 110, button "B" 112, or button "C" 114 are pressed, assuming that the button is pressed within a time window specified for medication dispensing.

Instructions for use of that particular medication are immediately shown on display 104 to further simplify the patient's medication therapy. By these means a patient may be given several medications for use during the same period without the usual concern with patient inability or unwillingness to understand and follow such a complicated regimen. The time of day and date when each dose is dispensed are recorded in the dispenser's memory for later retrieval and analysis by the host system.

When the dispenser is returned to the therapist at the end of the medication period, the therapist may use the host computer to "debrief" dispensing unit 100 to retrieve dispensing data and analyze the level of patient compliance to the regimen. Both summary and detailed analyses are provided, allowing the therapist to adjust the regimen and/or counsel the patient with confidence that comes from knowing to what extent the medications were properly taken.

The special strip packaging and associated sprocket drive developed for the first generation device are detailed in parent U.S. patent application Ser. No. 06/722,073 which was filed on Apr. 11, 1985 which issued as U.S. Pat. No. 4,674,652 on 6/87. Articles, or containers enclosing articles, are mounted at intervals along the strip such that the articles or containers are engaged by depressions on ejector sprocket segments 130, 132 and 134 and moved to the dispensed position by rotation of the sprocket. The circumferential spacing of the depressions around the sprocket matches the interarticle spacing along the strip and provides a flexible rack and pinion type drive mechanism.

FIG. 2 is a front view of an empty cartridge 200 into which medication can be loaded. Cartridge 200 is intended to be fitted into cartridge cavity 102 or 320 or 322 (cartridge cavities 320 and 322 are visible in FIG. 5) when dispensing unit 100 is loaded by the pharmacist or physician. Cartridge 200 utilizes the same dimensional standards as the first generation device, that is, all passageways are less than two and greater than one article diameter in width. However, cartridge 200 is a separate and distinct element that is easily loaded into and removed from dispensing unit 100, rather than being a part of the device as in the first generation unit. Thus, the unique dimensions need only be incorporated into the cartridges, and the dispenser housing need only simple, non-critical storage volume dimensions necessary to properly position the cartridges such that the leading end of the packaging strips are next to the dispensing sprocket segments.

FIG. 3 is a side view of a cartridge 200 and FIG. 4 is a front view of an cartridge 200 loaded with a packaging strip 202. Packaging strip 20 includes the actual sleeved strip 204 and medication containers 206.

FIG. 5 is a perspective view of dispensing unit 100 with the left side removed and the top flipped open. A cartridge 200 has been inserted into a cartridge cavity 102. This drawing shows the proper relationship of packaging strip 202 and its component parts to the sprocket drive mechanism of dispensing unit 100. Several such cartridge dispensing stations may be placed side by side to make a multiple strip dispenser.

As shown in FIGS. 1 and 5, the presently preferred embodiment of dispensing unit 100 includes three dispensing stations. I is anticipated that packaging strips 202 would be loaded into cartridges such as cartridge 200 automatically or semi-automatically by specially designed machines. These loaded cartridges would then be available for later use when they could be quickly loaded into dispensing unit 100 without need of any special tools or skills. A loaded cartridge is simply slipped into an appropriate cartridge cavity such as cavities 102, 320 or 322 of dispensing unit 100 and the first medication container 206 a the end of packaging strip 202 is pulled out of the cartridge and placed into the ejector sprocket segment associated with that cartridge such as, for example, ejector sprocket segment 130, ejector sprocket segment 132, or ejector sprocket segment 134, so that, upon the next rotation of the sprocket, the article is moved out of the dispenser and made available to the patient. In this manner a cartridge is loaded into each of the available cartridge cavities.

In FIG. 5, with the top of dispensing unit 100 flipped up, plunger pins 310, 312, and 314, are associated with button "A" 110, button "B" 112, and button "C" 114, respectively. It will be further explained below how these plunger pins interact with the ejector sprocket segments to initiate and permit dispensing. Additional cartridge cavities, namely cartridge cavity 320 and cartridge cavity 322 are also visible in this drawing. Electronic control system 326 is located in lid portion 324 of dispensing unit 100.

A locking pin 328 mates with a locking mechanism 330 located in the lid portion 324 of dispensing unit 100. The pharmacist or physician who is programming dispensing unit 100 can unlock it. However, from the patients point of view, dispensing unit 100 appears as an integral unit that can not be opened.

FIG. 6 is a perspective view of the right side of dispensing unit 100. Driving power for the dispensing mechanism may be supplied by a gear motor 340. Although manual operation is also possible, use of gear motor 340 to drive the ejectors simplifies operation for the patient and eliminates the force needed to turn the shaft. Reliability is also improved since all of the dispensing operations are then under the precise control of the dispenser control systems. Improper sequencing, purposeful or inadvertent misdirection of the driving shaft, binding, and overrotation are avoided. Power can be provided through an AC adapter port 600 and communications with the host system can be carried out via a communication port 602.

The driving force may be directly coupled to the drive shaft as shown in FIG. 6, or the transmission linkage may be made more compact by using gears, pulleys and belts or other common transmission elements. The common drive shaft 342 is a special rod that extends across the front of all of the storage cartridges. Ejector sprocket segments 130, 132 and 134 are slipped over this shaft and held in place in front of respective cartridge openings by means of spacers. These sprockets normally are not engaged by the drive shaft and remain motionless as the drive shaft rotates inside them.

FIG. 7 is a side view and FIG. 8 is a front view of ejector sprocket segment 130. All three ejector sprocket segments are the same, so only ejector sprocket segment 130 is shown. Ejector sprocket segment 130 is shown as having three article engaging depressions evenly spaced around its periphery, i.e. depression 350, depression 352, and depression 354. Sprockets having fewer or more depressions on correspondingly smaller or larger diameters could be used as an alternative embodiment as long as the spacing between depressions matches that between articles along the strip. The angle through which the sprocket must turn in order to bring the article from the secure ready position to the accessible dispensed position would also have to be adjusted.

Thus, there is a separate ejector sprocket segment, i.e. ejector sprocket segment 130, ejector sprocket segment 132, and ejector sprocket segment 134, for each dispensing station. When a particular cartridge containing station is selected by the patient to dispense another of its medication containing containers, the ejector sprocket segment associated with that station is connected to the drive shaft and then rotates with the drive shaft until the article is clear of dispensing unit 100 and accessible t the patient. Once the dispensing action is complete, the selected ejector sprocket segment automatically disengages from the drive shaft and is locked in place until properly selected again. In this manner any of the stations may be selected individually for dispensing and that station's ejector sprocket segment may rotate to dispense without the other dispensing ejector sprocket segments operating. Thus, articles of a particular type may be selectively dispensed from a dispenser containing many other articles of other types by means of clutches acting on a common driving shaft driven by a common driving force.

A clutch system is incorporated into each sprocket to allow it to engage and then automatically disengage the common drive shaft 342. FIG. 9 shows drive shaft 342 as having a passage 356 therein. Actually, there are three such passages in drive shaft 342 for each ejector sprocket segment.

FIG. 10 is a cut away side view of drive shaft 342 showing passages 356 associated with one of the ejector sprocket segments.

FIG. 11 is a cross section of ejector sprocket segment 130. Spring loaded pins, i.e. spring loaded pin 360, spring loaded pin 362, and spring loaded pin 364, one for each depression of ejector sprocket segment 130, are mounted such that they normally extend beyond the outside diameter of a hub at the end of ejector sprocket segment 130.

FIG. 12 is another cross section of ejector sprocket segment 130 showing the arrangement of spring loaded pin 360 in greater detail. Spring loaded pin 360 has a collar portion 370 that rests on a ring 376. Spring loaded pin 360 is biased by a spring 374.

FIGS. 13, 14, 15, and 16 are a series of drawings showing the operation of an ejector at various points in time. The sprocket hub rotates within a collar which incorporates a forward motion stop 500 that interferes with one of the sprocket pins when the sprocket is in its ready position. Another collar stop 502 prevents another of the three sprocket pins from moving in the reverse direction. Thus, in its ready position (FIGS. 13 and 16), a sprocket cannot rotate because pins prevent either its forward or reverse rotation and the drive shaft is free to turn within the ejector sprocket segment without engagement.

The lower end of each of the spring loaded sprocket pins 360, 362 and 364 normally rests just outside the inside diameter of the ejector sprocket segment and avoids interference with the drive shaft. However, when the selector pushbutton (button "A" 110, button "B" 112, or button "C" 114) for that particular ejector sprocket segment is depressed, the plunger pin, for example, plunger pin 310 engages the top of a spring loaded pin such as, for example, spring loaded pin 360 and pushes it downward (FIG. 14) so that the opposite end of the spring loaded pin enters a passage such as passage 356 in drive shaft 342. Passage 356 in drive shaft 342 has a chamfered opening for ease of spring loaded pin entry even when slightly misaligned and a close fitting diameter to firmly engage the depressed spring loaded pin. The depressed selector pushbutton, such as for example, button "A" 110, also acts as a switch that activates the driving mechanism only when the pin has been fully depressed. The switch function is provided by electrical contact 366, electrical contact 368, and electrical contact 380 which are shown in FIGS. 13-16. In FIGS. 13, 15 and 16, the switch is in its "standby" position and in FIG. 14, the switch is in its "dispense" position. Once fully depressed and engaged with the drive shaft, spring loaded pin 360 is then clear of forward motion stop 500 in the collar.

If the request to dispense is proper, the control system will then activate gear motor 340 causing drive shaft 342 to rotate in the forward direction. Since the selected ejector sprocket segment is engaged by the spring loaded pin extending into drive shaft 342, the selected ejector sprocket segment also rotates forward (FIG. 15) and dispenses the next article from th packaging strip associated with that sprocket. Once drive shaft 42 and the ejector sprocket segment have rotated approximately 120 degrees (for a sprocket with three depressions), the spring loaded pin that has engaged drive shaft 342 and has been kept depressed by a cam 510 on the collar, reaches a point where it can spring outward again. This outward movement causes the lower end of the pin to disengage the drive shaft and stop sprocket rotation at the proper position for a completed dispensing movement (FIG. 16). Another spring loaded pin is now against the forward motion stop 500 thereby preventing any sprocket coasting in the forward direction. Stop 500 also prevents the patient from pulling the strip beyond the dispensed position. The pin that was providing sprocket drive now interferes with reverse motion stop 502 if the patient should attempt to push the sprocket backwards.

Thus, the cartridge selector pushbuttons and spring loaded pins act as a clutch system that can individually engage any of the sprockets for dispensing their associated strip held articles and that automatically disengages at the completion of a dispensing cycle. The selector pushbutton serves to both mechanically activate the spring loaded pin clutch mechanism and electrically signal when the pin has been fully depressed and gear motor 340 action may begin. The dispenser's control circuit and programming checks to see that only one selector pushbutton has been depressed before activating the gear motor. The circuits and software also check to verify that the selector pushbutton has been released before the gear motor cycle is completed. A switch 700 (shown in FIG. 6) activated by a cam on the drive shaft signals when a dispensing cycle is complete. Thus, a mechanically simple and reliable segmented sprocket drive system with compact mechanical clutches is used to avoid the expense and size of separate dispensers, or single dispensers with a motor for each cartridge, or expensive and bulky standard clutch mechanisms.

FIGS. 17 and 18 are cross sections showing locking pin 328 and its interaction with locking mechanism 330. Locking mechanism 330 includes a solenoid, not shown, that controls the movement of a bar 378 which interacts with locking pin 328 to lock or unlock lid portion 324 of dispensing unit 100 from its lower portion. When the solenoid has pulled bar 378 to the unlock position a smaller diameter portion of bar 378 will pass through a slot in pin 328.

FIGS. 19(a) and 19(b) together form a block diagram of the microprocessor based dispenser electronic control system 326. The microprocessor 400 has mask programmed, on-board read only memory (ROM) 402 that stores the basic operating program without the need for external ROM that would require additional space and power. Microprocessor 400 also has associated therewith volatile random access memory RAM 404 for scratchpad storage of intermediate results. A wait mode is available that reduces power consumption during standby periods.

A combination real time clock 406 and random access memory 408 provide time of day and date information, periodic one minute alarm signals to wake the microprocessor out of its wait mode, and storage locations for the medication specific dispensing instructions supplied from a host system. A lithium battery 410 provides backup power for clock 406 and RAM 408. In this manner the dispenser never loses track of time or dispensing instructions even if the unit's power is interrupted. This on-board battery can power this section of the circuitry for up to ten years.

Another battery backed up device, the nonvolatile random access memory 412, backed up by a second lithium battery 414 is used for nonvolatile storage of data that may be used to determine when the dispenser actually dispensed articles. Like real time clock 406, the nonvolatile random access memory's 412 on-board battery 414 will protect the dispensing data for up to ten years in the absence of any other power.

An eight character alphanumeric liquid crystal display 104 (see also FIG. 1) supplies the patient with a wide variety of information. The time of day when the next dispensing operation for any of the dispensing stations is due is the normally displayed information. If no doses are due to be dispensed for the remainder of the day, the display will read "TOMORROW". As a dispensing operation is being completed, the display may provide a message that instructs the patient on how to administer the dispensed medication. Usually these messages will be longer than eight characters and will be scrolled across the display. Thus, almost any length message may be accommodated. If the patient attempts to dispense a medication at an improper time or otherwise attempts to use the dispenser in an improper manner, an appropriate and complete error message may be displayed. Not only doe the patient learn that the attempted operation is not appropriate, but he is also given the information needed to correctly use the device. The display can also provide prompting and status labels that aid the physician or pharmacist in loading and debriefing the dispenser. A buzzer 416 functioning as alarm 106 (see FIG. 1) is included to provide audible signalling. These signals are used to bring the patient's attention to the device when a dispensing operation is overdue. Proper and improper use of the dispenser can be indicated by the pitch and duration of the tone as controlled by the microprocessor. Alarms of various and/or multiple frequencies may be employed to match the hearing deficiencies of a particular patient.

The dispenser's electronics includes means to communicate with a host system for the purpose of receiving dispensing instructions and sending records of actual dispensing operations for analysis. These communication means include input and output ports 418 on the microprocessor that are connected to terminals in the housing walls. Only three leads are required for these purposes, making possible the use of small, simple connectors. RS-232 level conversion devices may be used to interface the microprocessor level signals to those of standard serial ports on host systems. Although data is transferred at the rate of 1200 baud in the preferred embodiment, almost any baud rate could be chosen. Error checking routines in the microprocessor and host system software help insure error free data transmissions. Special socket terminals on the dispenser housing may be used in place of the standard three conductor connector 420. Spring loaded connector pins on a communication interface device are then able to make rapid connection. The special sockets on the dispenser are blind holes that do not allow an opening into the electronics housing as a standard connector would.

Power for the portable dispenser is normally supplied from an AC adapter plugged into connector 600 on the side of the dispenser. AC line power is converted to low voltage DC power for use by the dispenser. A self contained nickel cadmium battery 424, continuously trickle charged while AC adapter 422 is connected, provides full operating power for up to seven days or more during portable use and other AC power interruptions. The lithium batteries in the real time clock and nonvolatile random access memory described above can preserve the essential data stored within their memories for as long as ten years.

The dispenser housing 500 (see FIG. 1) would usually be built of engineering plastics that can provide the lightweight strength required for reliable portable use. Three essentially identical cartridge cavities 102, 320 and 322 are arranged side by side so that the cartridges may be easily loaded from the top. Ejector sprocket segment 130, ejector sprocket segment 132, and ejector sprocket segment 134 are installed on drive shaft 342 and rest in collars at the front of each dispensing station. Thus, when the cartridges are loaded from the top into the cartridge holders, it becomes easy to pull the first article in the strip packaging forward and lay it into the sprocket depression that is in the ready position. The hinged lid portion 324 of dispensing unit 1? ? is lowered and latched thereby simultaneously securing all of the cartridges and all of the first strip articles into their respective sprockets.

A locking mechanism 330, operated by a solenoid 426 locks lid portion 324 of dispensing unit 100, thereby preventing unauthorized entry. Solenoid 426 can only be actuated by the proper command sent by the host system during loading and debriefing operations. Although a simple keyed cabinet latch could have been used instead, the hidden solenoid latch provides a more friendly and tamper proof design.

The hinged lid portion 324 of dispensing unit 100 contains electronic control system 326. Connections for three conductor connector 420 and AC adapter 422 may be located in any convenient location.

A cradle (not shown) may be used to support the open lid of the dispenser during loading and unloading and to provide convenient connection to the host computer system communication port. One integrated circuit is sufficient to interface the dispenser to a RS-232 host computer serial port and may be located in the cradle or more simply in the connector housing used to connect to the serial port of the host computer.

FIGS. 20(a) and 20(b) together constitute a flowchart of the dispenser firmware. The dispenser is normally in its wait mode in order to conserve power. During this approximately 59 second standby period each minute, the system is inactive except for a message displayed on the liquid crystal clock and the operation of the real time clock. Once a minute the real time clock generates an alarm signal that interrupts the microprocessor and wakes it from the wait mode. The microprocessor then proceeds to check the time of day and date against the schedules for each of the three dispensing stations. If any of the stations is overdue for dispensing, the microprocessor generates two one second alarm signals on the buzzer to get the patient's attention. The microprocessor then prioritizes the next dispensing times for the three dispensing stations and displays the next upcoming time on the display. Flags are set or reset for each of the dispensing stations to indicate whether a dispensing operation will be allowed if requested. The microprocessor then returns to the wait mode to conserve power and await the passage of another minute when the process would be repeated using updated time of day and date information. Thus, the patient always knows which medication to take and when, without the effort of understanding and remembering several simultaneous schedules.

The microprocessor is also awakened from the wait mode when any of the selector pushbuttons is depressed for a dispensing request. The program first checks to see if the dispense flag has been set for that particular dispensing station. If the request to dispense that particular medication is proper, the microprocessor actuates the gear motor. The dispense flags were set during the once a minute regimen checks so that the decision to dispense can be made quickly while the pushbutton is still depressed. Since the sprocket clutch is ready to engage only while the pushbutton is depressed, the gear motor 340 must be activated before the pushbutton is released. The engaged sprocket then moves the next medication dosage out of the dispenser for use by the patient. Instructions for use of that particular drug are then shown on the display so that the patient need not be confused when using multiple medications. If the once a minute alarm had been sounding for an overdue dose, the alarm will cease when dispensing is complete or if the dose is so late that it is considered missed. The program then rechecks the stored dispensing schedules and displays the next prioritized dispensing time and sounds the alarm if it is overdue. Finally, the program returns to the wait mode.

If the selected dispensing station is not properly available when its selector pushbutton is depressed, an appropriate error message, which was determined at the previous once per minute regimen check, will be displayed and an error alarm sounded.

An advantage of using an alphanumeric display and scrolling message software is apparent when long dispensing instructions and error messages need to be used to improve patient understanding of dispenser operations. The dispenser's instruction manual is thus included in its software and always automatically available to the patient. Instructions for taking each of the drugs are also always available, are applied to the appropriate drug automatically, and cannot be lost or forgotten. The patient is always presented with the appropriate instructions no matter how many medications are simultaneously prescribed.

The three selector pushbuttons, i.e. button "A" 110, button "B" 112, and button "C" 114 serve multiple functions. Not only do they signal a request from the patient to dispense from the three dispensing stations, they also provide the drug therapy supervisor with means to select particular functions while loading and debriefing the dispenser. The dispenser control system can distinguish between a dispensing request and a communications request because a signal is present on the communication lines that is not present during normal dispensing operations. Thus, these same three selector pushbuttons that allow the patient to select a dispensing operation also allow the drug therapy supervisor to select a loading, debriefing, or demonstration function. Multiple use of these few switches saves space, weight, and cost and decreases hardware complexity thereby improving reliability.

FIG. 21 is a block diagram of the host system hardware. FIGS. 22(a) and 22(b) together constitute a flow chart of the host system software which explains the interaction of the host system with the dispensing unit 100.

A loading operation is initiated by connecting three conductor connector 420 of dispensing unit 100 to the host system and pressing a selector pushbutton that has been designated for signalling host system communication requests. During the loading operation, dispensing unit 100 first sends a few bytes of information that identifies that particular dispenser unit to the host system. Then the host computer may request the dispenser to demonstrate proper operation of any of several dispenser functions. These tests include lighting all segments of display 104, operating buzzer 416, operating gear motor 340, and actuating solenoid 426 so that the dispenser may be opened for loading. After the medication cartridges have been loaded into the dispenser and first doses engaged on the sprockets, the drug types are identified to the host computer by means of reading a bar code label on each cartridge, and then the dispenser cabinet top is closed and latched. After cartridge loading is complete, the dispenser receives from the host system regimen data for each of the dispensing stations and time of day and date information to reset the on-board real time clock if necessary. At completion of the loading operation, the dispenser microprocessor checks the regimens and goes to the wait mode to await a dispense request, or a load or debrief host system request, or the once per minute real time clock interrupt to update the regimen status flags.

A host system debriefing request is similarly initiated by connecting the dispenser to the host system communication port and pushing the selector pushbutton designated for communications requests. The dispenser microprocessor then transmits identification, regimen, and time of actual dispensing data to the host system. Error checking routines verify that the host computer received the proper data.

The dispenser keeps time of actual dispensing data in the form of error data since that requires less storage space than a full representation of the time of day and date information. Since the host computer can reconstruct all essential information from just the error data, reduced storage requirements are possible. The error value is the difference between the prescribed dispensing time and the actual dispensing time. The resolution of this error data is set at 15 minutes since that is sufficient for medication regimen purposes. Resolution down to hundredths of a second is easily obtained from the real time clock. However, increased resolution must be balanced against the additional memory space required to store the higher resolution numbers.

Once the dispenser has transmitted the dispensing data to the host system for compliance analysis, the dispenser microprocessor checks regimens against the present time of day and date and returns to the wait mode to await the start of another cycle.

A host system would typically consist of a computer with serial communications port, printer, color monitor, and bar code reader. Virtually any computer system could be used as the host device for this dispensing system. The host computer must have sufficient on-line memory to run the load and debrief programs and sufficient storage capacity to maintain the necessary dispenser, patient, and medication files.

The drug therapist is first presented with the main menu which offers loading, debriefing, and file maintenance selections. When the loading program is selected, the therapist is instructed to connect the dispenser to the host system communication port and press the dispenser's selector pushbutton designated for signalling loading operations. The dispenser then transmits its identification code so that the host system can retrieve the latest loading record for that particular dispenser. The therapist next indicates whether the previous patient or a new patient is to use the dispenser next. If the same patient will use the device again, the program stores that information and proceeds to questions concerning the medications to be dispensed. If a different patient is to use the dispenser, a pop-up menu is used to select the patient's name from the stored patients' files. Once the proper patient has been identified, the host computer retrieves that patient's file and displays its contents. The therapist may then verify that the correct patient has been identified and review any special conditions for that patient that might be relevant to the dispensing operation.

Once the patient identification is complete, the program proceeds to identify the medication to be dispensed from each dispensing section. Dispensing schedules and instructions for each dispensing section are also input. A bar code reader connected to the host system may be used to rapidly read a bar code on the cartridges to quickly and accurately identify the contents of each dispensing station. Drug identification codes may also be typed in manually or selected from pop-up menus. The cartridge holders and video prompts may be color coded to aid in correlating the proper drug data with the correct dispensing station.

For each cartridge loaded, the therapist must select dispensing instructions options that will govern the dispensing operations for that particular medication. When the loaded medications are first identified, the program retrieves the files for those medications and suggests typical dispensing parameters for those drugs. The therapist then has the choice of accepting the suggested typical schedules and other parameters or modifying them to suit any particular needs.

The dispensing frequency is first defined. For the medical dispenser the four options are once, twice, three, or four times per day. Other frequencies and uneven intervals might be appropriate for dispensing other types of articles and are equally within the capabilities of this dispensing system. Once the dispensing frequency has been defined, the daily schedule of prescribed dispensing times is selected. In the case of the medication dispenser, on-the-hour dispensing times are selected but any target times could be used if appropriate for other applications.

The therapist also defines the allowable tolerance around the target dispensing time. Because the dispenser has complete locking control of the dispensing operations, the patient can be restricted to dispensing within predefined periods before and after the prescribed dispensing time. For instance, the dispenser may be instructed to allow access to a particular cartridge up to three hours before and four hours after the prescribed dispensing time. Any combination of early and late periods is possible including continuous access. The early and late period resolution may range from months to seconds depending upon the degree of control necessary.

Even more complicated definitions of access time could be accommodated. For example, a fixed number of dispensings within a specified period could be defined for a particular medication as the only limiting parameter. Or the dispenser could be instructed to enforce a minimum interval between dispensing operations with or without specifying a prescribed target dispensing time. Overdosing of a particular medication can thus be prevented. A minimum interval may be set either with respect to just one of the cartridge medications or taking into consideration dispensing operations of all the cartridges in the dispenser. Thus, if the effectiveness of one medication would be reduced by the presence of another, a twelve hour interval could be maintained between the dispensing of the two medications. The system is therefore capable of maintaining priorities among multiple dispensing operations and can, as required, prevent or cause interaction among dispensed medications by coordinating their dispensing times and accessibility. This sophisticated control capability, both for individual dispensing sections and for coordination of all the dispensing sections in combination, provides novel dispensing capabilities in such a compact and portable dispensing device.

The first dosing time is next selected from the daily dosing times. The therapist also can specify a starting day delay ranging from none to several days or weeks. Thus, the first dose and starting day offset parameters allow the therapist to precisely control when the regular dispensing operations will start for each dispensing section of the dispenser. The therapist can thereby program the dispenser in advance for the convenience of his and/or his patient's schedule.

The delayed starting option also may be used to extend the total dosing endurance for a medication by loading more than one cartridge of that drug into the dispenser and programming the additional cartridges to be accessible after earlier used cartridges have been exhausted. Dosing periods of six weeks or more can be attained by this method when using the three cartridge dispenser loaded with the same medication in all three compartments.

The total number of articles to be dispensed from a particular cartridge is also selected so that the dispenser knows when to stop prompting and dispensing for that cartridge.

Alarm usage may also be defined. The alarm can be programmed to sound only when the dispensing operation is overdue, or in advance to help insure timely dispensing, or not at all. These alarm options are selected for each dispensing section.

Messages to be displayed upon dispensing a medication may also be specified. For each dispensing section the therapist may chose from a standard set of messages or may input a custom message. A suggested standard message for that particular medication is provided when the host system identifies the drug in that cartridge but the therapist is free to modify or substitute for that standard message. These messages serve to help the patient properly use the dispensed medication. Instructions, warnings, or any other type of message may be provided. These messages may be much longer than eight characters since the dispenser microprocessor will scroll long messages across the display. The amount of information conveyed by these messages is only limited by the storage capacities for these messages in the dispenser memory elements.

The host system loading program also collects prescribing physician information. Emergency phone numbers are then readily available to the therapist in case a consultation with the prescribing physician is necessary. The program also automatically keeps track of the number of allowed and used refills for each medication loaded.

Once all of the identification and dispensing parameters data has been gathered from the therapist by the host system, the loading program converts the dispensing control data into a convenient form for use by the dispenser. This conversion of the control data into a form that is directly usable and preassembled for the dispenser saves dispensing unit software complexity. It is easier for the higher level host system computer to convert these data than for the dispenser's microprocessor to do so. After conversion, these identification and dispensing control data are automatically sent to the dispenser over the three wire communications link where it is stored in nonvolatile memory. Error checking routines verify that the stored data are the same as those sent.

The host system loading program then consolidates the loading data into a summary report and stores it on the host system archival storage medium, usually a hard disk. This record is then available as a memorandum of how the dispenser was programmed for that use period. A paper copy of this record may also be generated on the host system printer for use in the patient's, dispenser's, or therapist's hard copy files. At the completion of these loading documentation operations, the program returns to the main menu for selection of another function.

A dispenser function test routine is available from both the loading and debriefing programs. The functions test menu includes commands that will cause testing of the dispenser's buzzer, liquid crystal display, gear motor and solenoid latch devices. Thus, the therapist can verify that the loaded dispenser is sent out properly functioning and that any returning dispenser is still functioning properly at the end of the dispensing period.

The host system debriefing function is also selected from the main menu. After connection of the returned dispenser to the communication link, a selector pushbutton designated for signalling a debriefing request is pushed and causes the automatic transfer to the host system of all the data loaded into the dispenser at the start of the dispensing period and all of the data collected as the articles were dispensed. The collected dispensing data contains dispensing time error data. Because the host system recalls all of the dispensing schedule and control data from that dispenser's latest loading report, the host computer can reconstruct from the dispensing time error data the time of day and date when the medication was actually dispensed. The returned dispenser identification and dispensing parameters data is compared against the loading record to insure that data remained unchanged throughout the dispensing period.

The collected error data and the calculated time of day and date data are used to provide detailed reports of dispensing activity for each of the dispensing stations. A summary is first displayed on the host system color monitor which gives key information at a glance. Color coding of the displayed information speeds assimilation by the therapist and quickly identifies any problem areas requiring special attention. The primary information displayed on this first screen is the compliance level for each of the medications dispensed. The compliance levels are determined by comparing the patient's actual dispensing behavior to the prescribed dispensing schedule and by comparing the extent of any discrepancies to standards set for that medication. Those standards may have been set by the manufacturer of the drug, the drug therapist, or by some other method. The adequacy of the actual dispensing behavior in comparison to whatever standards are considered appropriate is quantified and displayed for each of the dispensing sections.

Several compliance scores may be calculated from the data. A cumulative compliance score may be calculated that is the ratio of the number of doses actually dispensed to the number of doses prescribed for the period. The cumulative compliance score then is a measure of total dosage compliance.

Another index can be computed that measures the effectiveness of the doses that were taken. This daily compliance score measures the number of medication dosing intervals during which the patient was under or over medicated. The actual dosing intervals are compared to the prescribed dosing intervals and intervals that are longer or shorter than some allowed length of interval tolerance are counted and weighted according to how excessively short or long the improper interval is. The daily compliance score then is a measure of how well the medication levels matched the prescribed levels irrespective of actual dispensing times.

By subtracting the daily compliance score from the cumulative compliance score an overall compliance index can be developed. Calculating an overall compliance index is one manner in which the entire set of dispensing data for a particular cartridge can be reduced to a manageable level. Such an index allows a quick, yet relatively complete, evaluation of patient compliance to the prescribed regimen and the probable effectiveness of the drug therapy.

Any compliance scores not meeting established standards are flagged by displaying them in a flashing red color. Thus, by means of this single screen summary of dispensing operations, the therapist may quickly evaluate the adequacy of the dispensing operations for each cartridge without having to decode and analyze all the compliance data details. If the summary indicates that the dispensing operations were within allowable limits for all of the cartridges, the therapist may elect to save time by not reviewing the more detailed data presented in later screens.

If the summary screen shows that a compliance problem exists, or if the therapist cares to examine the dispensing data in detail for any reason, detailed dispensing data for each cartridge may be viewed in graphic and tabular form in full screen, color displays. FIG. 23 reproduces one such graphical presentation. These detailed graphic displays again allow immediate identification of non compliant operations by means of color coded graphs of dispensing error versus prescribed dosing times. Once the problem areas are shown on the graph, the therapist may use the cursor to point to those non-compliant operations and the program will display the actual dispensing time, the prescribed dosing time, and the amount of error in numeric form for an exact measure of the noncompliance for that one dispensing operation.

Thus, both summary level and detailed data are available to the therapist for both a rapid and a thorough evaluation of patient compliance to the prescribed regimens. The host system will save all dispensing data to its dispensers' and patients' files. A paper copy of any of the summary or detailed information may be generated and saved for statistical and archival purposes. The host system program returns to the main menu after completion of debriefing operations. The dispenser resumes normal dispensing operations after disconnection from the communications link.

The compliance analysis will now be described. The following parameters are important in evaluating patient compliance. The final computer generated compliance report includes the following information. These parameters allow the physician or pharmacist to adequately asses all potential aspects for poor compliance to a prescribed medication regimen.

1. Shortest dosing interval (hours)

2. Longest dosing interval (hours)

3. 24 hour intervals without medication (number of occurrences)

In addition to these, there are six calculations carried out to allow for adequate assessment of patient compliance based on the data collected by the compliance monitor.

The following definitions apply:

Prescribed Values

Total Dosing Period (Days)=D

Prescribed Dosing Frequency (Daily)=F

Longest Prescribed Dosing Interval (Hours)=I.sub.L

Shortest Prescribed Dosing Interval (Hours)=I.sub.S

Total Doses Prescribed=D.multidot.F

Empirical Values

Total Doses Dispensed=d

Dosing Intervals Less Than I.sub.S =i where n=dose number i.sub.sn is any i (in hours) where i<I.sub.S

Dosing Intervals Greater Than I.sub.L =i.sub.1n where n=dose number, i.sub.1n is any i (in hours) where i>I.sub.L

Short interval outlier (0.sub.sn)=any i.sub.sn <I.sub.S /X

where X is >1 and chosen based on toxicity profile of drug

Long interval outlier (O.sub.1n)=any i.sub.1n >I.sub.L .multidot.Y

where Y is >1 and chosen based on efficacy and elimination characteristics of drug

Dosing frequency during any 24 hour period (p)=f.sub.p

Dosing Frequency Less Than F

f.sub.1p is any f where f.sub.p <F

Dosing Frequency More Than F

f.sub.mp is any f where f.sub.p >F

A Cumulative Compliance Score (CCS) is calculated as a simple percentage of the total doses consumed during a given time period, divided by the total doses prescribed during this time period, multiplied by 100.

A Daily Compliance Score (DCS) calculation allows for a value to quantitate overall compliance. Patients could have a very high CCS and yet not have taken the medication according to the prescription. The DCS evaluates patient compliance on an individual daily basis and provides a single value to facilitate evaluation. The DCS is calculated by determining the shortest (I.sub.S) and longest (I.sub.L) prescribed intervals. Actual dosing intervals (i) are then calculated--the first interval (i.sub.1) being between the time the initial dose was prescribed and the time the first dose was actually taken. The second interval (i.sub.2) is the time between first and second dose, etc. The last interval is calculated as the time between the last dose taken and the time the last dose was prescribed. Short interval outliers (O.sub.sn) are divided into the shortest prescribed interval and summed. Long interval outliers (O.sub.1n) are divided by the longest prescribed interval and these values are summed. These two sums derived from short and long intervals are added and divided by the total number of doses dispensed. This value is called the Daily Compliance Score. ##EQU1##

An Overall Compliance Score (OCS) is a simple calculation provided by subtracting the DCS times ten from the CCS. A good compliance is proportional to a higher overall compliance score with the perfect score being 100. Acceptable limits for all three of the above indices will vary by drug, as well as by physician or pharmacist interpretation.

An Over-Use Score (OUS) screens for periods of time when the medication was taken in very short intervals (I.sub.s) or at minimally acceptable intervals over an extended period of time. This value is calculated by the summation of the shortest prescribed interval (I.sub.s) divided by the short interval outliers (O.sub.sn). This value is then added to the sum of the number of doses which exceed the maximum prescribed frequency in 24 hour periods, divided by the number of doses prescribed per 24 hour period. Twenty-four hour periods may not overlap. The total is then divided by the total doses taken. ##EQU2##

An Under-Use Score is calculated by the summation of each long interval outlier divided by the longest prescribed interval (I.sub.L). This value is added to the summation of 24 hour frequencies which were less than the prescribed frequency, divided by the prescribed 24 hour frequency. Twenty-four hour periods may not overlap. The summation of these two values, divided by the total doses used, is called the Under-Use Score. ##EQU3##

In addition to the above, mean interval and standard deviation will be provided, as well as normalized standard deviation, which is calculated by standard deviation divided by the mean prescribed interval.

The above calculations, automatically carried out by the microprocessor provide evaluation of patient compliance by highlighting the cumulative effect of under-use or over-use of drugs throughout the prescription period as well asanalyzing overall drug intake. In addition to these, by considering individual drug absorption, serum half-life, effective blood levels and toxic ranges, calculations can be made using empirical dosing data to identify periods where therapeutic levels of drugs are not available to the patient or dangerously high levels exist.

While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of appended claims. ##SPC1## ##SPC2## ##SPC3## ##SPC4## ##SPC5## ##SPC6## ##SPC7## ##SPC8## ##SPC9##