Electronic control of drug delivery system

Abstract

In an exemplary embodiment, a drug delivery device for driving an electrotransport current through a body surface of a user is provided. The device includes a patch with two electrodes and one or more reservoirs storing a therapeutic agent. The one or more reservoirs release the therapeutic agent into the body surface of the user when the reservoirs are positioned over the electrodes to form an electrical path for the electrotransport current. The device includes a controller which controls a controllable power supply to drive the electrotransport current through the body surface of the user in a predetermined profile.

1 . In a drug delivery device, a method of driving an electrotransport current through an animal body surface using a controller of the device to deliver at least a portion of a therapeutic agent, the method comprising:
 driving the electrotransport current through electrodes of the device and through the animal body surface using a controllable power supply of the device;   determining a present value of the electrotransport current;   determining a dynamic value representative of a target electrotransport current, the dynamic value determined based on the target electrotransport current, a resistance value of a sense resistor used to detect the electrotransport current flowing between the electrodes, a value of a bandgap voltage associated with the controller, and a fixed voltage value; and   controlling the controllable power supply using the controller at least based on the present value of the electrotransport current and the dynamic value representative of the target electrotransport current.   
     
     
         2 . The method of  claim 1 , wherein the controller controls the controllable power supply using a linear regulator. 
     
     
         3 . The method of  claim 1 , wherein the controller controls the controllable power supply using a switching regulator. 
     
     
         4 . The method of  claim 2 , wherein the switching regulator performs pulse width modulation (PWM) and the controllable power supply is a PWM power supply. 
     
     
         5 . The method of  claim 4 , further comprising:
 controlling a duty cycle of the PWM power supply using the controller at least based on the present value of the electrotransport current and the dynamic value representative of the target electrotransport current.   
     
     
         6 . The method of  claim 4 , further comprising:
 controlling a duty cycle of the PWM power supply using the controller based on a comparison between the present value of the electrotransport current and the dynamic value representative of the target electrotransport current.   
     
     
         7 . The method of  claim 4 , further comprising:
 determining a present value of an output voltage applied across the animal body surface;   determining a dynamic value representative of the target output voltage;   making a comparison between the present value of the output voltage and the dynamic value representative of the target output voltage; and   controlling a duty cycle of the PWM power supply using the PWM controller based on the comparison.   
     
     
         8 . The method of  claim 7 , wherein controlling the duty cycle of the PWM power supply further comprises:
 determining that the present value of the output voltage is greater than the dynamic value representative of the target output voltage based on the comparison; and   reducing the duty cycle of the PWM power supply by one step without performing an electrotransport current correction.   
     
     
         9 . The method of  claim 7 , wherein controlling the duty cycle of the PWM power supply further comprises:
 determining that the present value of the output voltage is less than or equal to the dynamic value representative of the target output voltage based on the comparison; and   performing an electrotransport current correction.   
     
     
         10 . The method of  claim 9 , wherein performing the electrotransport current correction comprises:
 making a second comparison between the present value of the electrotransport current and the dynamic value representative of the target electrotransport current;   determining that the present value of the electrotransport current is greater than the dynamic value representative of the target electrotransport current based on the second comparison; and   reducing the duty cycle of the PWM power supply by one step.   
     
     
         11 . The method of  claim 9 , wherein performing the electrotransport current correction comprises:
 making a second comparison between the present value of the electrotransport current and the dynamic value representative of the target electrotransport current;   determining that the present value of the electrotransport current is equal to the dynamic value representative of the target electrotransport current based on the second comparison; and   maintaining the duty cycle of the PWM power supply at its present step.   
     
     
         12 . The method of  claim 9 , wherein performing the electrotransport current correction comprises:
 making a second comparison between the present value of the electrotransport current and the dynamic value representative of the target electrotransport current;   determining that the present value of the electrotransport current is less than the dynamic value representative of the target electrotransport current based on the second comparison; and   increasing the duty cycle of the PWM power supply by one step.   
     
     
         13 . The method of  claim 1 , wherein an output voltage applied across the animal body surface is maintained below a maximum value irrespective of changes in a resistance of the animal body surface to avoid burning the animal body surface. 
     
     
         14 . The method of  claim 1 , further comprising:
 detecting if there is a minimum level of energy in a battery of the device; and   driving the electrotransport current through the animal body surface only if the battery has the minimum level of energy.   
     
     
         15 . The method of  claim 1 , further comprising:
 shutting down the device upon detecting a potential safety issue; and   providing an indication that the device has been shut down.   
     
     
         16 . The method of  claim 15 , wherein the potential safety issue is detected during operation of the device if a battery voltage is below a minimum voltage for a predefined time duration. 
     
     
         17 . The method of  claim 15 , wherein the potential safety issue is detected during operation of the device if the electrotransport current is higher than a maximum current for a first predefined time duration. 
     
     
         18 . The method of  claim 15 , wherein the potential safety issue is detected during operation of the device if the electrotransport current is lower than a minimum current for a second predefined time duration. 
     
     
         19 . The method of  claim 15 , wherein the potential safety issue is detected during operation of the device if an output voltage applied across the animal body surface is higher than a maximum voltage for a predefined time duration. 
     
     
         20 . The method of  claim 1 , further comprising:
 immediately after turning on the drug delivery device, applying an output voltage across the animal body surface for a predefined time duration without controlling the power supply.   
     
     
         21 . The method of  claim 1 , further comprising:
 controlling the electrotransport current in a predetermined profile, wherein the predetermined profile is a fixed current value for a predetermined time duration, the fixed current value based on one or more characteristics of the animal body surface, the animal body, and/or the therapeutic agent.   
     
     
         22 . The method of  claim 1 , further comprising:
 detecting if the electrotransport current reaches a minimum level of current within an initial period after switching on the device; and   switching off the electrotransport current if the electrotransport current does not reach the minimum level of current within the initial period.   
     
     
         23 . The method of  claim 22 , further comprising:
 switching on the device one or more times until a battery of the device is depleted.   
     
     
         24 . The method of  claim 1 , further comprising:
 controlling the electrotransport current in a predetermined profile, wherein the predetermined profile is selected based on a characteristic of the animal body surface.   
     
     
         25 . The method of  claim 1 , further comprising:
 controlling the electrotransport current in a predetermined profile, wherein the predetermined profile is selected based on a characteristic of the therapeutic agent.   
     
     
         26 . The method of  claim 1 , further comprising:
 programming the controller to drive the electrotransport current through the animal body surface in a first predetermined profile; and   changing the programming of the controller to drive the electrotransport current through the animal body surface in a second predetermined profile.   
     
     
         27 . The method of  claim 1 , further comprising:
 programming the controller to slowly drain a power supply of the device at the end of dosing of the therapeutic agent.   
     
     
         28 .- 51 . (canceled) 
     
     
         52 . The method of  claim 1 , wherein the therapeutic agent comprises, sumatriptan succinate. 
     
     
         53 . One or more computer readable media storing instructions executable by a processing unit for driving an electrotransport current through an animal body surface using a controller to deliver at least a portion of a therapeutic agent, the media comprising instructions for:
 driving the electrotransport current through electrodes and through the animal body surface using a controllable power supply;   determining a present value of the electrotransport current;   determining a dynamic value representative of a target electrotransport current, the dynamic value determined based on the target electrotransport current, a resistance value of a sense resistor used to detect the electrotransport current flowing between the electrodes, a value of a bandgap voltage associated with the controller, and a fixed voltage value; and   controlling the controllable power supply using the controller at least based on the present value of the electrotransport current and the dynamic value representative of the target electrotransport current.   
     
     
         54 . The method of  claim 1 , wherein the dynamic value representative of the target electrotransport current is determined based at least on the target electrotransport current and an operational characteristic of a power supply that varies during operation of the power supply. 
     
     
         55 . The method of  claim 54 , wherein the operational characteristic of the power supply is a variable output voltage of the power supply. 
     
     
         56 . The method of  claim 54 , wherein the dynamic value representative of the target electrotransport current is determined based at least on a reference voltage at an analog-to-digital converter that varies during operation of the power supply.