Electrotransport delivery device with voltage boosting circuit

Abstract

An electrotransport device ( 10 ) for delivering therapeutic agents includes an adjustable voltage boost multiple controller ( 100, 200 ) for boosting the voltage from a power source ( 102, 202 ) to a working voltage V W having a value just sufficient to provide the desired therapeutic current level I I through the electrodes ( 108, 112 ), at least one of which contains the therapeutic agent to be delivered.

1 . A method of operating an electrotransport delivery device for delivering a therapeutic agent through an animal body surface, the device having a source of electrical power with an output voltage, comprising: 
 (a) boosting the power source output voltage to a working voltage which drives an electrotransport current through the animal body surface;    (b) sensing a body surface parameter selected from the group consisting of electrical resistance of the body surface, voltage drop across the body surface, and the electrotransport current through the body surface;    (c) adjusting the boost multiple, and thereby the working voltage, responsively to the sensed body surface parameter.    
     
     
         2 . The method of  claim 1 , wherein the power source comprises a DC power source.  
     
     
         3 . The method of  claim 1 , wherein the power source comprises a battery.  
     
     
         4 . The method of  claim 1 , wherein the sensed body surface parameter is electrotransport current applied through the animal body surface.  
     
     
         5 . The method of  claim 1 , wherein the sensed body surface parameter is the electrical resistance of the animal body surface.  
     
     
         6 . The method of  claim 5 , wherein the animal body surface is skin and the body surface parameter is skin resistance.  
     
     
         7 . The method of  claim 1 , including adjusting the adjustable boost multiple to keep the applied electrotransport current substantially constant.  
     
     
         8 . The method of  claim 1 , including adjusting the adjustable boost multiple to keep the applied electrotransport current following a predetermined current-time profile.  
     
     
         9 . The method of  claim 1 , wherein the working voltage is adjusted to a minimum value required to maintain the electrotransport current at a predetermined level.  
     
     
         10 . The method of  claim 1 , including electrically connecting an inductor to a source of electrical power for a time T 1 , thereby charging the inductor to a peak instantaneous current I p ; and then discharging the inductor for a time T 2 , into a filter capacitor.  
     
     
         11 . The method of  claim 10 , including sensing the peak instantaneous inductor current and limiting the peak instantaneous inductor current to avoid saturating the inductor.  
     
     
         12 . The method of  claim 11 , which includes the step of limiting the time T 1 .  
     
     
         13 . The method of  claim 10 , including the step of adjusting the time, T 1 , to adjust the working voltage responsively to the current sensed in the load current path.  
     
     
         14 . The method of  claim 10 , including the step of adjusting the time, T 2 , to adjust the working voltage responsively to the current sensed in the load current path.  
     
     
         15 . An electrotransport delivery device for delivering a therapeutic agent through an animal body surface, the device having a source of electrical power with an output voltage and two electrodes for applying an electrotransport current through the body surface, the device comprising: 
 (a) a voltage booster having an adjustable boost multiple for boosting the power source output voltage to a working voltage which drives an electrotransport current through the animal body surface;    (b) a body surface parameter sensor, the sensor being effective to sense a body surface parameter selected from the group consisting of electrical resistance of the body surface, voltage drop across the body surface, and electrotransport current applied through the body surface;    (c) an adjuster for adjusting the boost multiple, and thereby the working voltage, responsively to the sensed body surface parameter.    
     
     
         16 . The device of  claim 15 , wherein the power source comprises a DC power source.  
     
     
         17 . The device of  claim 15 , wherein the power source comprises a battery.  
     
     
         18 . The device of  claim 15 , wherein the adjuster adjusts the boost multiple to keep the electrotransport current constant.  
     
     
         19 . The device of  claim 15 , wherein the adjuster adjusts the boost multiple to apply an electrotransport current having a predetermined current-time profile.  
     
     
         20 . The device of  claim 15 , wherein the sensed body surface parameter is electrotransport current applied through the animal body surface.  
     
     
         21 . The device of  claim 15 , wherein the sensed body surface parameter is the electrical resistance of the animal body surface.  
     
     
         22 . The device of  claim 21 , wherein the animal body surface is skin and the body surface parameter is skin resistance.  
     
     
         23 . The device of  claim 15 , wherein the adjuster is effective to adjust the boost multiple, and thereby the working voltage, to a minimum value required to maintain the electrotransport current at a predetermined level.  
     
     
         24 . The device of  claim 15 , including a first controlled switch means for connecting an inductor to the power source for a time T 1 , thereby charging the inductor to a peak instantaneous current Ip; and a second controlled switch means for discharging the current in the inductor, for a time T 2 , through a uni-directional rectifying device into a filter capacitor.  
     
     
         25 . The device of  claim 24 , including a sensor for sensing the peak instantaneous inductor current and a limiter for limiting the peak instantaneous inductor current to avoid saturating the inductor.  
     
     
         26 . The device of  claim 25 , including a timer for limiting the time T 1 .  
     
     
         27 . The device of  claim 15 , including a timer for adjusting the time, T 2 .