the detailed description contained in this specification is intended to illustrate the principles of the invention and not to limit them . a limited number of illustrative embodiments are presented as examples and , it is anticipated , that others would occur to those skilled in the art which would be within the scope of the inventive concept . fig1 represents an iontophoretic patch device that automatically releases a dosage of granisetron or other therapeutic agent upon application of the device to the skin . that device is additionally capable of releasing a second dosage after a patient activates a switching device . the embodiment of fig1 illustrates an iontophoretic self - powered skin - applied adhesive patch device generally at 10 . the patch includes a cathode chamber or counter reservoir 12 containing a cathode or counter electrode 14 and an anode chamber or donor reservoir 16 containing a pair of anodes 18 and 20 spaced and electrically isolated from each other , but electrically connected to respective conductors 22 and 24 and to the material in the reservoir 16 . a two - position switch element is shown at 26 and a pair of power sources , which may be conventional button - type batteries are shown connected in series at 28 and 30 . additional interconnecting conductor elements are shown at 32 , 34 and 36 . thus , using the switch 26 , either anode 18 or 20 can be selectively connected or patched into a circuit which is completed by the application of the patch 10 to the skin of a patient , as is well known . the charge capacity and so the dosage associated with either anode 18 or 20 can further be adjusted to any desired amount as by adjusting the content of oxidizable species at each anode such that depletion of the oxidizable species or isolation of the connection will produce an open circuit condition with that anode connected . techniques for this are illustrated and described in u . s . pat . no . 6 , 653 , 014 assigned to the same assignee as the present application and which is hereby incorporated by reference herein for any purpose . although one and two - anode devices are shown in the figures , it will be appreciated that , optionally , additional anodes , conductors and switch positions could readily be added , if desired . the circuit , optionally , can include elements to limit or control current flow in a known manner to produce a longer - lasting lower dosage at any switch position . for example , it may be desired to administer a low steady dose of granisetron of perhaps about 40 μg / hr over a long period of time after an initial bolus or first primary dose has been administered . also , additional or other types of dc power sources and controls including programmed controls optionally such as shown in fig3 , for example , can be used . in operation , when the iontophoresis patch device of fig1 is adhesively applied to the skin of a patient , this will complete a first circuit including a selectively included anode 18 , 20 and the patch will immediately activate and begin to deliver a dosage of granisetron or other therapeutic agent contained in the anode or donor reservoir commensurate with the amount of oxidizable species available to the circuit at the then connected anode . this will preferably be preset by the position of the switch 26 set at the point of manufacture so that a known initial bolus of the granisetron as an initial therapeutic dosage can be delivered rapidly as soon as the device is applied to the skin of a user . thereafter , if a second or so - called “ rescue ” dose is required , it can be triggered when the user operates the switch 26 to the alternate position to connect a second or alternate anode 18 , 20 in the circuit to self - administer an additional dose of granisetron . the alternate embodiment of fig2 includes a similar skin - applied , self - powered adhesive patch 40 which includes a cathode chamber or counter reservoir 42 with cathode or counter electrode 44 , an anode chamber or donor reservoir 46 provided with a single anode or donor electrode 48 . a normally open switch or other activation element or device 50 , connected with an associated sensor 52 for receiving external activation signals , is provided in the circuit between anode 48 and a pair of series - connected power sources 54 and 56 . connecting conductive elements are shown at 58 , 60 , 62 and 64 . this embodiment is designed to be worn by one potentially in need of receiving a dose of the therapeutic material of the patch . activation of the patch and delivery of the medication , however , is controlled by an externally generated signal being received by sensor 52 which , in turn , triggers the element 50 to close a switch or otherwise function to complete the circuit . the embodiment 40 is shown with a single anode and so is designed to deliver a single dose to the wearer . it will be appreciated that the sensing device 52 may be designed to receive any of many types of signals including radio frequency , audio , infrared , etc ., and a single signal may activate the patches of many wearers as might occur among troops commonly engaged in a military setting . this embodiment provides a means for automated iontophoretic transdermal granisetron administration in a military field setting , as may be required for example , with an unexpected exposure of soldiers to radiation and / or chemical and biological agents . fig4 depicts a sensor - activated embodiment 40 a , similar to that shown in fig2 that is provided with a user activated element to provide protection against unwanted activation of the patch ( such as in storage ). thus , the embodiment of fig4 is provided with a manually - operated switch as at 70 which is designed to be closed by the user prior to sensor - controlled activation . in an open position , switch 70 interrupts the power on conductor 60 thereby disconnecting the power source 56 . the closing of the switch 70 also actives the sensor 52 which is otherwise in an off mode . this embodiment is shown with a single power source 56 but as was the case in the embodiment of fig2 , additional power sources , or other controls as in fig3 , of course , may be used . once the switch 70 is adjusted to the closed position by the user , the system is enabled for automated sensor - controlled activation . a further embodiment 10 a is shown in fig3 in which an electronic control circuit or element 37 is connected by a conductor 38 to switch 26 and by a conductor 39 to power source 28 . the electronic control circuit element 37 may include a microprocessor or a microprocessor - operated control which may be a timing controller such as are well known and which may operate in conjunction with a single donor electrode 20 a to deliver a plurality of doses from the patch as controlled by the element 37 and switch 26 . this is an alternative operating scheme to that of sequential electrode depletion shown in fig1 . the control system may be used to provide a sustained or steady low - level delivery of therapeutic agent . in the case of granisetron , this may be about 30 - 50 μg / hr and preferably about 40 μg / hr , for example . the examples of the detailed description show the administration of a therapeutic agent in which the donor reservoir is the anode chamber . of course , as previously indicated , for example , it will be recognized by those skilled in the art that an oppositely charged material might be administered using the cathode chamber as the donor reservoir and the anode chamber as the counter reservoir . other variations in configuration and control are also contemplated . these may include circuit components to control delivery power over time or the like . this invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use such specialized components as are required . however , it is to be understood that the invention can be carried out by specifically different equipment and devices , and that various modifications , both as to the equipment and operating procedures , as well as materials , can be accomplished without departing from the scope of the invention itself .
a disposable skin - worn device for the transdermal delivery at least one dose of charged therapeutic substances , including granisetron , by iontophoresis , the device comprising a donor reservoir containing an amount of a therapeutic substance to be delivered transdermally by iontophoresis , a counter reservoir , a source of electric power connected in a circuit between the donor reservoir and the counter reservoir and a control system for controlling current flow in the circuit to enable at least one dose of the therapeutic substance to be delivered transdermally by iontophoresis and wherein the control system includes a control element selected from the group consisting of a sensor activated by an external signal and a switch .