Note: Descriptions are shown in the official language in which they were submitted.
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ELECTROTRANSPORT DEVICE HAVING REUSABLE
CONTROLLER POWER SAVER
TECHNICAL FIELD
The invention relates to electrotransport drug delivery systems having
a drug containing delivery unit and a reusable control unit having an
electrically powered control circuit, the units separably connected by a
s mechanical coupler.
BACKGROUND ART
The term "electrotransport" as used herein refers generally to the
delivery of an agent (eg, a drug) through a membrane, such as skin, mucous
membrane, or nails. The delivery is induced or aided by application of an
~o electrical potential. For example, a beneficial therapeutic agent may be
introduced info the systemic circulation of a human body by electrotransport
delivery through the skin. A widely used electrotransport process,
electromigration (also called iontophoresis), involves the electrically
induced
transport of charged ions. Another type of electrotransport, electroosmosis,
~s involves the flow of a liquid, which liquid contains the agent to be
delivered,
under the influence of an electric field. Still another type of
electrotransport
process, electroporation, involves the formation of transiently-existing pores
in a biological membrane by the application of an electric field. An agent can
be delivered through the pores either passively (ie, without electrical
2o assistance) or actively (ie, under the influence of an electric potential).
However, in any given electrotransport process, more than one of these
processes may be occurring simultaneously to a certain extent. Accordingly,
the term "electrotransport", as used herein, should be given its broadest
possible interpretation so that it includes the electrically induced or
enhanced
2s transport of at least one agent, which may be charged, uncharged, or a
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mixture thereof, whatever the specific mechanism or mechanisms by which
the agent actually is transported.
Electrotransport devices use at least two electrodes that are in
electrical contact with some portion of the skin, nails, mucous membrane,
s or other surface of the body. One electrode, commonly called the "donor"
or "active" electrode, is the electrode from which the agent is delivered into
the body. The other electrode, typically termed the "counter" or "return"
electrode, serves to close the electrical circuit through the body.
For example, if the agent to be delivered is positively charged, ie, a cation,
~o then the anode is the active or donor electrode, while the cathode serves
to
complete the circuit. Alternatively, if an agent is negatively charged,
ie, an anion, the cathode is the donor electrode. Additionally, both the
anode and cathode may be considered donor electrodes if both anionic and
cationic agent ions, or if uncharged or neutrally charged agents, are to be
~s delivered.
Furthermore, electrotransport delivery systems generally require at
least one reservoir or source of the agent to be delivered, which is typically
in the form of a liquid solution or suspension. Examples of such donor
reservoirs include a pouch or cavity, a porous sponge or pad, and a
2o hydrophilic polymer or a gel matrix. Such donor reservoirs are electrically
connected to, and positioned between, the anode or cathode and the body
surface, to provide a fixed or renewable source of one or more agents or
drugs. Electrotransport devices also have an electrical power source such
as one or more batteries. Typically, one pole of the power source is
25 electrically connected to the donor electrode, while the opposite pole is
a
electrically connected to the counter electrode. In addition, some
electrotransport devices have an electrical controller that controls the
current
applied through the electrodes, thereby regulating the rate of agent delivery.
Furthermore, passive flux control membranes, adhesives for maintaining
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device contact with a body surface, insulating members, and impermeable
backing members are other optional components of an electrotransport
device.
All electrotransport agent delivery devices utilize an electrical circuit
s to electrically connect the power source (eg, a battery) and the electrodes.
In very simple devices, such as those disclosed in Ariura et al
US Patent 4,474,570, the "circuit" is merely an electrically conductive wire
used to connect the battery to an electrode. Other devices use a variety of
electrical components to control the amplitude, polarity, timing, waveform
~o shape, etc of the electric current supplied by the power source.
See, for example, McNichols et al US Patent 5,047,007.
To date, commercial transdermal electrotransport drug delivery
devices (eg, the Phoresor, sold by loured, Inc. of Salt Lake City, UT;
the Dupel lontophoresis System sold by Empi, Inc. of St. Paul, MN;
~s the Webster Sweat Inducer, model 3600, sold by Wescor, Inc. of Logan, UT)
have generally utilized a desk-top electrical power supply unit and a pair of
skin contacting electrodes. The donor electrode contains a drug solution
while the counter electrode contains a solution of a bio-compatible
electrolyte
salt. The "satellite" electrodes are connected to the electrical power supply
Zo unit by long (eg, 1-2 meters) electrically conductive wires or cables.
Examples of desk-top electrical power supply units which use "satellite"
electrode assemblies are disclosed in Jacobsen et al US Patent 4,141,359
(see Figures 3 and 4); LaPrade US Patent 5,006,108 (see Figure 9); and
Maurer et al US Patent 5,254,081 (see Figures 1 and 2). The power supply
is units in such devices have electrical controls for adjusting the amount of
electrical current applied through the electrodes. The "satellite" electrodes
are connected to the electrical power supply unit by long (eg, 1-2 meters)
electrically conductive wires or cables. Wire connections are subject to
disconnection, limit patient movement and mobility and can also be
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uncomfortable. The wires connecting the power supply unit to the electrodes
limits their separation to the length of the wires provided.
More recently, small self contained electrotransport delivery devices
adapted to be worn on the skin, sometimes unobtrusively under clothing,
s for extended periods of time have been proposed. The electrical
components in such miniaturized electrotransport drug delivery devices are
also preferably miniaturized, and may be either integrated circuits
(ie, microchips) or small printed circuits. Electronic components, such as
batteries, resistors, pulse generators, capacitors, etc, are electrically
connected to form an electronic circuit that controls the amplitude, polarity,
timing, waveform shape, etc of the electric current supplied by the power
source. Such small self contained electrotransport delivery devices are
disclosed for example in Tapper US Patent 5,224,927; Sibalis et al
US Patent 5,224,928 and Haynes et al US Patent 5,246,418. Unfortunately,
~s as electrotransport delivery devices become smaller, the power source
(eg, batteries) used to power the devices, must also become smaller and
hence, battery capacity and battery life become more of a design problem.
In addition to electrotransport devices becoming smaller, there have
recently been suggestions to utilize electrotransport devices having a
Zo reusable controller which is adapted to be used with multiple drug-
containing
units. The drug-containing units are simply disconnected from the controller
when the drug becomes depleted and a fresh drug-containing unit is
thereafter connected to the controller. In this way, the relatively more
expensive hardware components of the device (eg, batteries, LED's,
25 circuit hardware, etc) can be contained within the reusable controller, and
the
relatively less expensive donor reservoir and counter reservoir matrices can
be contained in the disposable drug containing unit thereby bringing down
the overall cost of electrotransport drug delivery. Examples of
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electrotransport devices comprised of a reusable controller adapted to be
removably connected to a drug-containing unit are disclosed in
Sage, Jr. et al, US Patent 5,320,597; Sibalis, US Patent 5,358,483;
Sibalis et al, US Patent 5,135,479 (Fig. 12); and Devane et al
s UK Patent Application 2 239 803.
DESCRIPTION OF THE INVENTION
It is an aspect of the present invention to provide an electrotransport
system in which the power source in the reusable control unit is electrically
disconnected from the current controlling circuit, which circuit includes a
~o closed internal circuit path, until the time when the unit is ready to be
used.
The present invention is directed to preserving battery strength and
extending battery life in an electrotransport device comprised of a reusable
electronic controller adapted to be used with a plurality of single use
(eg, disposable) drug-containing units. After the drug has been depleted
~s from the drug-containing unit, the unit is disconnected from the controller
and
discarded, and then replaced with a fresh one. The controller includes a
power source (eg, one or more batteries) and a circuit for controlling the
timing, frequency, magnitude, etc of the current applied by the device.
The control circuit includes an internal circuit, such as a timing circuit,
2o which at the time the device is in operation, is in contact with both poles
of
the battery through a circuit path other than the patient's body. A switch is
provided for keeping the batteries electrically isolated from the closed
internal circuit until the time when the device is placed in operation.
The switch is closed automatically by coupling the disposable drug-
2s containing unit to the reusable electronic controller. The switch is
automatically reopened, and the battery(ies) again put in electrical
isolation,
when the drug-containing unit is uncoupled from the reusable controller.
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The invention is useful in any electrotransport
device comprised of a reusable controller and single
use/disposable drug units, particularly for preventing
current drain during shelf life between the time when the
device is manufactured and the time it is first used on a
patient. The invention is particularly useful in
electrotransport devices having long periods of non-use (eg,
over night, on holidays/weekends, etc) once the controller
is unpackaged and put into use.
It will be appreciated that the "agent" or
"therapeutic agent" suitable for use in the invention means
in the broadest sense any pharmaceutically-acceptable agent,
and preferably therapeutically active substances, such as
drugs or prodrugs, which are delivered to a living organism
to produce a desired, and usually beneficial, effect.
Examples of suitable agents are described in Gyory, et a1.
U.S. Patent 5,169,383, Sorenson, et a1. U.S. Patent
5,207,752, Sage, Jr., et al. U.S. Patent 5,320,597, Myers,
et al. U.S. Patent 5,405,317, and Myers, et a1. U.S. Patent
5,543,098. In U.S. Patent 5,169,383, for example, suitable
therapeutic agents for electrotransport are defined to
include: anti-infectives such as antibiotics and antiviral
agents; analgesics such as fentanyl, sufentanil,
carfentanil, lofentanil, alfentanil, hydromorphone,
oxycodone, propoxyphene, pentazocine, methadone, tilidine,
butorphanol, buprenorphine, levorphanol, codeine,
oxymorphone, meperidine, dihydrocodeinone, opioids, cocaine
and analgesic combinations; anesthetics; anorexics;
antiarthritics; antiasthmatic agents such as terbutaline;
anticonvulsants; antidepressants; antidiabetics agents;
antidiarrheals; antihistamines; anti-inflammatory agents;
antimigraine preparations; antimotion sickness preparations
such as scopolamine and ondansetron; antinauseants;
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antineoplastics; antiparkinsonism drugs; antipruritics;
antipsychotics; antipyretics; antispasmodics including
gastrointestinal and urinary; anticholinergics;
sympathomimetrics; xanthine derivatives; cardiovascular
preparations including calcium channel blockers such as
nifedipine; beta-agonists such as dobutamine and ritodrine;
beta blockers; antiarrythmics; antihypertensives such as
atenolol; ACE inhibitors such as ranitidine; diuretics;
vasodilators including general, coronary, peripheral and
cerebral; central nervous system stimulants; cough and cold
preparations; decongestants; diagnostics; hormones such as
parathyroid hormones; hypnotics; immunosuppressives; muscle
relaxants; parasympatholytics; parasympathomimetrics;
prostaglandins; proteins; peptides; psychostimulants;
sedatives and tranquilizers.
Additional agents include fentanyl hydrochloride,
pilocarpine nitrate, lidocaine hydrochloride, hydrocortisone
derivatives, sodium salicylate, acetic acid, fluoride anion,
lithium, antibiotics such as penicillin and cephalosporin
and dexamethasone sodium phosphate, hydromorphone, diazepam
salts, antihypertensive agents, bronchodilator agents,
peptide hormone and regulatory agents and proteins.
Also described in U.S. Patent 5,169,383 are
suitable agents including peptides, polypeptides, proteins,
and other macromolecules, which are otherwise difficult to
deliver transdermally or transmucosally because of their
size. As indicated in U.S. Patent 5,169,383, these
macromolecular substances typically have a molecular weight
of at least about 300 Daltons, and more typically, a
molecular weight in the range of about 300 to 40,000
Daltons. However, smaller and larger peptides are also
described as being deliverable by electrotransport.
Examples of peptides and proteins given and which may be
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delivered by electrotransport include, without limitation,
LHRH, LHRH analogs such as buserelin, gonadorelin, naphrelin
and leuprolide, GHRH, GHRF, insulin, insulinotropin,
heparin, calcitonin, octreotide, endorphin, TRH, NT-36
(chemical name: N-[[(s)-4-oxo-2-azetidinyl]carbonyl]-L-
histidyl-L-prolinamide], liprecin, pituitary hormones, e.g.
HGH, HMG, HCG, desmopressin acetate, follicle luteoids,
alpha-ANF, growth factor releasing factor (GFRF), beta-MSH,
somatostatin, bradykinin, somatotropin, platelet-derived
growth factor, asparaginase, bleomycin sulfate, chymopapain,
cholecystokinin, chorionic gonadotropin, corticotropin
(ACTH), erythropoietin, epoprostenol (platelet aggregation
inhibitor), glucagon, hirulog, hirudin analogs,
hyaluronidase, interferon, interleukin-2, menotropins, e.g.
urofollitropin (FSH) and LH, oxytocin, streptokinase, tissue
plasminogen activator, urokinase, vasopressin, desmopressin,
ACTH analogs, ANP, ANP clearance inhibitors, angiotensin 11
antagonists, antidiuretic hormone agonists, antidiuretic
hormone antagonists, bradykinin antagonists, CD4, ceredase,
CSF~s, enkephalins, FAB fragments, IgE peptide suppressors,
IGF-1, neurotrophic factors, colony stimulating factors,
parathyroid hormone and agonists, parathyroid hormone
antagonists, prostaglandin antagonists, pentigetide, protein
C, protein S, renin inhibitors, thymosin alpha-1,
thrombolytics, TNF, vaccines, vasopressin antagonist
analogs, alpha-1 antitrypsin (recombinant), and TGF-beta, as
an agent-enhancer compound.
BRIEF DESCRIPTION OF THE DRAWINGS
In the figures, wherein like parts are given like
reference numerals and wherein;
Fig. 1 is a perspective view of a separable
electrotransport device in accordance with this invention;
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Fig. 2 is a cross sectional view of the device
shown in Fig. 1, taken along line 2-2 of Fig. 1, showing the
controller and the drug unit in an uncoupled configuration;
Fig. 3 is a cross sectional view of the device
shown in Fig. 1, taken along line 2-2 of Fig. 1, showing the
controller and the drug unit in a coupled configuration; and
Fig. 4 is an electrical schematic drawing of a
preferred embodiment of the present invention;
Fig. 5 is a cross sectional view of another
electrotransport device with the controller and the drug
unit in an uncoupled configuration, the drug unit having a
third stud 73;
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Fig. 6 is a cross sectional view of the device shown in Fig. 5 with the
controller and the drug unit in a coupled configuration;
Fig. 7 is a cross sectional view of another electrotransport device with
the controller and the drug unit in an uncoupled configuration, the controller
s having posts 312, 314 and the drug unit having a conductive strip 316; and
Fig. 8 is a cross sectional view of the device shown in Fig. 7 with the
controller and the drug unit in a coupled configuration.
MODE FOR CARRYING O~JT THE INVENTION
Fig. 1 is a perspective view of electrotransport device 50 having a
reusable electronic controller 52 which is adapted to be coupled to and
uncoupled from, drug-containing unit 70. The controller 52 is reusable,
ie, it is adapted to be used with a plurality of drug units 70, eg, a series
of
identical and/or similar drug units 70.. On the other hand, drug unit 70
~s typically has a more limited life and is adapted to be discarded after use,
ie, when the drug contained therein has been delivered or has been
depleted.
With reference to Fig. 2, there is shown a sectional view of the
system 50 along line 2-2 of Fig. 1, with the drug unit 70 uncoupled from the
Zo controller 52. The housing 56 of controller 52 encloses a printed circuit
(PC) board 58, a battery power source 60, comprised of two button cell
batteries connected in series, for powering the PC board 58 and a switch 62
for connecting and disconnecting the power source 60 from the PC board
58. The PC board 58 is formed in a conventional manner, having
2s conductive traces patterned for interconnecting components thereon.
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The drug unit 70 is configured to be removably coupled to the
controller 52, with the top of drug unit 70 adjacent to and facing the bottom
of the controller 52. The top of assembly 70 is provided with the male parts
of two snap type connectors, the male parts being studs 72 and 74 which
s extend upwardly from drug unit 70. The bottom portion of the housing 56 is
provided with two openings 64 and 66 which are positioned and sized to
receive studs 72 and 74, respectively.
The drug unit 70 includes a liquid impermeable, flexible insulating
substrate 71 which is adhered or laminated to foam member 75 having wells
77 and 79 therein. The substrate 71 may be made of a polyethylene foam
or polyester. The foam member 75 may be made of a layer of polyethylene
foam of predetermined thickness having the wells 77 and 79 defined by
punching or cutting as is well known in the art. The wells 77 and 79 each
contain a reservoir and optionally an electrode 81, 82, respectively.
15 Thus, well 77 contains reservoir 76 and optionally electrode 81,
and well 79 contains reservoir 78 and optionally electrode 82. At least one
of the reservoirs 76 and 78 (eg, reservoir 76) contains a therapeutic agent
(eg, a drug) to be delivered. Thus, electrode 81 and reservoir 76 may be
considered a donor electrode assembly while electrode 82 and reservoir 78
zo may be considered counter electrode assembly. The reservoirs 76 and 78
are typically formed from hydrogels and are adapted to be placed in contact
with the body surface (eg, skin) of a patient (not shown) when in use.
The reservoirs 76 and 78 are enclosed around the periphery of the
substrate 71 and isolated from each other by foam member 75. The bottom
2s (ie, patient contacting) surface of foam member 75 is preferably coated
with
a skin contact adhesive. A release liner 80 covers the body contacting
surfaces of the two reservoirs 76 and 78 and the adhesive coated surface of
foam member 75 before the unit 70 is put in use. The release liner 80 is
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preferably a silicone coated polyester sheet. The release liner 80 is
removed when the unit 70 is applied to the skin of a patient (not shown).
Studs 72 and 74 are made from an electrically conductive material
(eg, a metal such as silver, brass, stainless steel, etc or a metal coated
s polymer, eg, ABS with a silver coating). Thus, both studs 72 and 74 conduct
electric current supplied by controller 52. The stud 72 makes electrically
conductive contact with the electrode 81 and the reservoir 76 while stud 74
makes electrically conductive contact with the electrode 82 and the
reservoir 78.
~o Housing 56 of controller 52 has recesses 102 and 103 immediately
inboard of openings 64 and 66, respectively. Spring retainers 104 and 105,
which are electrically conductive and radially resilient, are configured to be
received by the recesses 102, 102'. The spring retainers 104 and 105 are
configured to removably latch in the respective circumferential grooves when
the studs 72 and 74 are inserted through openings 64 and 66. The studs
72, .74 are demountably retained by the respective spring retainers 104, 105,
thus removably connecting the drug unit 70 to the housing 56 of
controller 52.
Conventional electronic connecting means (eg, conductive wires,
2o traces or leaf springs (not shown) electrically connect the spring
retainers
104, 105 to respective conductive traces (not shown) on the bottom of the
PC board 58.
A switch 62 is mounted to the bottom of the PC board 58.
The switch 62 includes two terminals 112, 114 soldered or otherwise
2s electrically connected to respective traces (not shown) on the PC board 58.
One terminal 114 of the switch 62 is electrically connected to one pole of the
battery power source 60 while the other pole of the battery power source 60
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is electrically connected to system ground 125. The other switch terminal
112 is connected to an input terminal 126 of a current control circuit 128.
The switch 62 may be a conventional metal leaf spring switch or a
type SKHUAB, or SKHUAA switch, available from the Alps Electric(USA),
s Inc, San Jose, CA. The design of switch 62 is not critical as long as (i)
the
switch remains in an open position when no drug unit 70 is coupled to
controller 52, and (ii) the switch is closed when a drug unit 70 is coupled to
controller 52. The particular switch 62 illustrated in Figs. 2 and 3 is a
single
pole, single throw switch which includes a spring biased plunger 115 having
an actuating face 116 oriented roughly parallel to the bottom surFace of
controller 52. The switch 62 is disposed on the bottom of the PC board 56
such that the actuating face 116 and the opening 64 are aligned essentially
coaxial to the stud 72 when stud 72 is inserted into opening 64. The plunger
115 is shown in its fully extended position in Fig. 2, ie when the drug unit
70
is uncoupled from controller 52. Plunger 115 retracts against the force of the
internal spring when the stud 72 pushes against the actuating face 116
during the coupling of drug unit 70 to the controller 52.
The switch terminals 112, 114 are open (ie, the switch 62 is open)
when the drug unit 70 is uncoupled from the controller 52 and the spring in
Zo the plunger 115 is in an extended configuration. The switch terminals 112,
114 are electrically connected (ie, the switch 62 is closed) when the plunger
115 is in a retracted configuration, ie, when drug unit 70 is coupled to
controller 52 as shown in Fig. 3.
The PC board 58 and the switch 62 are mounted within the housing
is 56 such that the stud 72 simultaneously causes (i) plunger 115 to retract
and electrically connect the terminals 112, 114 of the switch 62, and
(ii) mechanically couple the drug unit 70 to the controller 52, by means of
the
spring retainer 104.
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The switch terminals 112, 114 are electrically connected in series with
a power supply circuit carried on PC board 58. While the present invention
is not limited to any current level, circuitry, time or mode of drug delivery,
one example of a timed power supply circuit (ie, applies electrotransport
s current to a patient for a predetermined period of time) is illustrated in
Fig. 4.
The control circuit 120 includes two output terminals 134 and 135 for
providing control current, Ic, to the electrode assemblies 81, 76 and 82, 78.
The controlled current, Ic, is supplied to the skin of a patient when the
electrode assembly 70 and controller housing 56 are mounted together as
~o described above, and the reservoirs 76, 78 are affixed to the skin or
mucous membranes of a patient. The power supply current, Ip, to the
control circuit 128 is zero until the two switch terminals 112, 114 are
connected by closure of the switch 62 (not shown in Fig. 4) upon actuation
of the plunger 115. The timing circuit 128, therefore is constrained to draw
no quiescent current from the power supply 60, and to supply zero current,
Ic, until the switch 62 is closed by the mechanical coupling of the drug unit
70 to the controller 52. This ensures that the energy stored in the power
source 60 will be conserved until the controller 52 and the drug unit 70 are
coupled as described earlier.
2o The two outputs 134, 135 are connected through the conductive
segments to the donor electrode assembly 81, 76 and counter electrode
assembly 82, 78 respectively, through conductive traces (not shown)
configured on the PC board 58, which make electrical contact with the
corresponding one of the ends of the spring retainers 104, 105.
zs The current, Ic , for supplying the therapeutic agent contained in the
reservoir 76, flows from the output 134, through the spring retainer 104,
the stud 82, the electrode 81 and the reservoir 76 into the body of the
patient (not shown). ,
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Alternative embodiments of a control circuit 120 may use other
controlled current waveforms than successive constant current values.
Pulsed, sinusoidal, ramp and multiple combinations of such various time
varying waveforms may also be supplied by the method of feedback control
s as desired.
In use, with reference again to Fig. 2- 4, the patient, or clinical
practitioner selects the reusable controller 52 and the desired disposable
electrode assembly 70. The controller 52 and assembly 70 may have been
stored in an inactive condition for an indefinite period of time without
causing
~o current drain from the battery power source 60 since the switch 62 is in a
normally open condition.
The studs 72 and 74 are aligned with the respective openings
64 and 66 in the housing 56 and inserted therein. The studs are self guided
upon insertion to make conductive contact with the respective spring
retainers 104 105. Continued insertion of the studs 72 and 74 causes the
spring retainers 104, 105 to slide around the heads of the studs until the
retainers 104, 105 engage with the grooves of the studs. Simultaneously,
the head of stud 72 physically displaces the actuator plunger 115 which
causes electrical connection between switch terminals 112, 114.
2o The terminals 112, 114 thus complete the connection of the power source 60
in the circuit 120. The engagement of the retainers 104, 105 in the grooves
of studs 72, 74 now complete the mechanical coupling of the housing 56 and
the drug unit 70 to form a single unit. Optionally, the completed coupling of
drug unit 70 to controller 52 may be signalled to the user by means of
25 flashing the LED 158 with a predetermined blinking pattern after the switch
62 is closed. The coupled device 50 is then placed on the body of a patient
with the reservoirs 76, 78 making contact with the patient body surface
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(eg, skin). When connection is made between the reservoirs 76, 78 and the
patient's skin, the current, Ic, begins to flow through the electrode
assemblies 81, 76 and 82, 78 and through the patient's body.
Delivery of controlled current, Ic, continues until completion of the
timed program in timing circuit 128, exhaustion of the therapeutic agent in
the reservoir 76 or removal of the system 50 from the patient's skin.
Completion of a predetermined time of therapeutic agent delivery or
exhaustion of the disposable electrode assembly 70 may be indicated,
for example, by flashing the LED 158.
The patient or clinical operator may then disengage the studs 72, 74
of exhausted drug unit 70 from the openings 64, 66 and retainer springs
104, 105 of the housing 56 by pulling the drug unit 70 away from the
housing 56. The removal of the stud 72 from opening 64 allows the plunger
115 to extend once again thereby causing switch 62 to open and disconnect
~s the power source 60 from the power circuit 120. Opening the power circuit
120 preserves the remaining battery charge on the power source 60.
A replacement drug unit 70 may be mounted to the housing 56 and installed
to actuate the switch 62 at a later time (eg, for another treatment on the
same or a different patient). Actuation of the switch 62 reconnects the
2o power circuit 120 by connecting the switch terminals 112, 114 and enables
the coupled controller 52 and drug unit 70 to be ready for application to the
patient and continuation of therapeutic agent delivery as before.
Referring now to Figs. 5 and 6 there is shown an electrotransport
device 150 comprised of a reusable electronic controller 152 and a
25 disposable drug unit 170. Unlike device 50 illustrated in Figs. 1-3,
the reusable controller 152 has a third opening 68 adapted to receive a third
stud 73 on drug unit 170. At least the head portion of stud 73 is composed
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of an electrically conductive material (eg, a metal or a metal coated
polymer). The bottom of circuit board 58 in controller 152 includes a pair of
spring terminals 212, 214 which are open and correspond in function to the
terminals 112, 114 in controller 52. When drug unit 170 is coupled to
controller 152, stud 73 extends through opening 68 and engages the spring
terminals 212, 214. Because the head of stud 73 is electrically conductive,
the engagement of stud 73 with a spring terminals 212, 214 closes the
circuit between the terminals 212, 214 and thereby connects the power
source 60 into the circuit 128.
Referring now to Figs. 7 and 8, an electrotransport device 250
comprised of a reusable electronic controller 252 and a disposable drug unit
270 is illustrated. Unlike device 50 shown in Figs. 1-3, device 250 includes
electrically conductive posts 312, 314 which extend through the bottom of
housing 56. The ends of posts 312, 314 are adapted to contact conductive
~s strip 316, which is carried on the upper surface of substrate 71, when the
drug unit 270 is coupled to controller 252, as shown in Fig. 8. Electrically
conductive post 312, 314 perform a similar funcfiion as the terminals 112,
114 in device 50. Thus, when the controller 252 is uncoupled from the drug
unit 270, an open circuit exists between the posts 312, 314, thereby
Zo electrically isolating the power source 60 from the circuit carried by the
circuit
board 58. Upon coupling the drug unit 270 to the controller 252, the posts
312, 314 engage the electrically conductive strip 316, thereby closing the
open circuit and connecting the power source 60 to the circuitry on circuit
board 58.
z5 Like device 50, illustrated in Figs. 2 and 3, devices 150 and 250 have
a mechanical switching means which isolates the power source 60 from an
internal closed loop timing circuit 128 on circuit board 58. But for the
mechanical switching means, the closed loop timing circuit 128 would
CA 02205010 1997-OS-09
WO 96/22124 PCT/L1S96/00427
otherwise draw small amounts of current, even without the drug units
coupled to the controller. Thus, the mechanical switching means
,.. -
(ie, switch 62, stud 73 and spring terminals 212, 214; and posts 312, 314 in
combination with conductive strip 316) prevents the closed internal circuit
s 128 from being electrically connected to the power source 60 until just
before the device is to be used, ie, when the drug unit is coupled to the
controller. Those skilled in the art will readily appreciate that other known
mechanical switches which draw no quiescent current from the power source
60 could be substituted for the switches illustrated in Figs. 2-3 and 5-8,
without departing from the spirit of the present invention.
While the device 50 illustrated in Figs. 2 and 3 has stud 72 which
performs two functions, namely electrically connecting electrode assembly
81, 76 to the circuit on circuit board 58, stud 72 also acts to close switch
62
and thereby connect the power source 60 to the circuit on circuit board 58.
15 However, this "dual functionality" is not required as is clearly shown in
devices 150 and 250 in Figs. 5-8.
While the foregoing detailed description has described one
embodiment of the electrotransport system having a reusable power saving
controller in accordance with this invention, it is to be understood that the
Zo above description is illustrative only and not limiting of the disclosed
invention. It will be appreciated that it would be possible for one skilled in
the
art to modify the shape, dimensions and materials of the housing,
the PC board, batteries, switch and conductive traces, the components
mounted and interconnected thereon, the electrode assembly, materials and
zs type and shape of connectors and retaining springs, or to include or
exclude
various elements within the scope and spirit of this invention. Thus the
invention is to be limited only by the claims as set forth below.
