Surgery – Means for introducing or removing material from body for... – Infrared – visible light – ultraviolet – x-ray or electrical...
Reexamination Certificate
1996-03-29
2001-01-16
Bockelman, Mark (Department: 3762)
Surgery
Means for introducing or removing material from body for...
Infrared, visible light, ultraviolet, x-ray or electrical...
C604S501000
Reexamination Certificate
active
06175763
ABSTRACT:
TECHNICAL FIELD
The invention relates to electrotransport devices which deliver a beneficial therapeutic agent (eg, a drug) through a body surface (eg, skin) and to indicators used to signal conditions of use or operation for such devices.
BACKGROUND ART
Electrotransport drug delivery devices have a wide range of application for transdermal delivery of therapeutic medicaments to individuals. Passive transdermal drug delivery systems employ a chemical concentration gradient and electrically-assisted (ie, electrotransport) transdermal drug delivery systems employ an electric field under control of an electronic controller to drive charged drug ions from a reservoir placed adjacent to the surface of the skin, through the skin (or a mucosal membrane) and into the bloodstream or body tissues.
Transdermal drug delivery systems are placed on the skin for some prescribed time period (eg, 24 hours) during which drug is delivered. In electrotransport devices, the transdermal drug flux, at least at certain applied current densities, is proportional to the level of applied current. The electrotransport drug flux can be controlled by controlling the magnitude and timing of the applied current. Thus, electrotransport devices afford greater control of transdermal drug flux than passive transdermal delivery systems. Because the magnitude of applied electrotransport current is typically quite low (eg, less than 150 &mgr;A/cm
2
), the patients generally cannot feel the applied electrotransport current. This can create some uncertainty, at least in those electrotransport devices having no on/off indicator (or other means for signaling when the device is on and applying electrotransport current), since neither the user (patient) nor the clinician have any immediate indication that the drug is being delivered as prescribed. A malfunction of the device may not be detected during use. An example of a malfunction may simply be that the system has run out of drug and therefore cannot continue to deliver drug at the prescribed rate.
In response to these problems, many electrotransport systems incorporate visual or audible displays to communicate the status or operating conditions to the user or clinician. See for example, Maurer et al, U.S. Pat. No. 5,254,081,
FIG. 3
element
70
shown as LEDs and buzzer; Bannon et al U.S. Pat. 5,135,480
FIG. 2
showing LCDs; Haak et al U.S. Pat. No. 5,246,417 showing LEDs,
FIG. 5
, elements 63-1 to 63-n; Sorenson, US SIR H71; DeVane UK Patent GB 2 239 803 A; and Brodard EP 0092015 October , 1983, showing a speaker for sounding an alarm.
The audible and visual displays of the prior art devices typically create lights or tones which may compete with similar lights and sound in crowded environments, creating the possibility that the display may be unnoticed. In some environments, for example, a quiet hospital ward, it may be undesirable to have disturbing or annoying lights or sounds. With visually-impaired or hearing-impaired patients, lights or sounds may not always be noticeable. Thus, there is a need for a means for notifying a patient of an electrotransport device condition without using visual or audible signals.
DISCLOSURE OF THE INVENTION
The present invention is directed to a method and apparatus for indicating an operating or other condition of an electrotransport drug delivery device. Examples of electrotransport device conditions include excessive or inadequate applied electrotransport current (which corresponds to excessive or inadequate electrotransport drug flux), excessive or inadequate skin resistance, drug exhaustion, reservoir pH, low battery strength and the like. The device includes a sensor for sensing the condition or status of the device or its operation and a tactile signal generator for generating and transmitting a tactile signal to the patient. Preferably the tactile signal is in the form of vibrations or “tingling” caused by an applied electric signaling current.
The present electrotransport drug delivery system senses and signals to the wearer (ie, the patient) (i) a condition or status of the system, and/or (ii) the occurrence of an event occurring during operation of the system. The system indicator comprises a sensor for sensing a condition or event associated with the operation of the system and a tactile signal generator for generating a tactile signal which can be sensed (ie, felt) by the patient. A controller, communicating with the sensor and the tactile signal generator, controls the tactile signal generator to generate the tactile signal when a predetermined condition or event is sensed by the sensor. The patient is thereby informed of the condition or event by sensing the tactile signal, without the need for any visual or audible signal.
The invention also includes a method of signaling a patient about the condition or status of an electrotransport drug delivery device or its operation. The method includes monitoring a condition or event associated with the operation of the system and generating a tactile signal, which signal can be felt by the patient wearing the system, when the condition or event occurs.
Different types of sensors for sensing different events and/or conditions may be used in the present invention. For example, sensors which sense (i) drug content in the donor reservoir, (ii) availability of electrochemically oxidizable or reducible species at the electrode/reservoir interface, (iii) battery voltage (iv) applied electrotransport current, (v) skin resistance, and/or (vi) pH of a donor or counter reservoir, can be used in connection with the present invention. One preferred sensor monitors the electrical resistance of the skin during transdermal electrotransport drug delivery. The sensor senses the skin resistance and the controller compares the sensed skin resistance to a predetermined acceptable skin resistance range. If the sensed skin resistance is outside the predetermined range, the controller causes the signal generator to generate a tactile signal, thereby alerting the patient to the abnormal operating condition (ie, skin resistance outside predetermined limits). Another preferred sensor is a pH sensor for monitoring the pH of a donor and/or counter reservoir in the electrotransport device and indicating when the reservoir pH exceeds, or falls below, a predetermined pH limit.
The tactile signal generator may be a piezo-electric transducer (for generating and transmitting a vibrational tactile signal) or an electric current source (eg, a battery) with appropriate electrical control circuitry to generate and transmit an electric signaling current to the patient's skin (eg, through the donor and counter electrodes which are in place on the skin).
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patent: 4781200 (1988-11-01), Baker
patent: 4919139 (1990-04-01), Brodard
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patent: 5045833 (1991-09-01), Smith
patent: 5135477 (1992-08-01), Untereker et al.
patent: 5135480 (1992-08-01), Bannon et al.
patent: 5169384 (1992-12-01), Bosniak et al.
patent: 5224928 (1993-07-01), Sibalis et al.
patent: 5415629 (1995-05-01), Henley
patent: 0092015 (1983-10-01), None
patent: 0 461 680 A2 (1991-12-01), None
patent: 2239803A (1991-07-01), None
patent: WO 88/08729 (1988-11-01), None
patent: WO 92/10234 (1992-06-01), None
Lattin Gary A.
McNichols Larry A.
Sorenson Paul D.
ALZA Corporation
Bates Owen J.
Bockelman Mark
Miller D. Byron
Stone Steven F.
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