Self-test for analgesic product
Electrotransport drug delivery devices, system and methods of using configured to determine if a current is present between the anode and cathode when drug is not intended to be delivered by the device. These devices/systems may include an off-current module to determine that any current (e.g., which may be inferred by measuring potential difference between the anode and cathode of the device) flowing between the anode and cathode is below a threshold value when the device is not supposed to be delivering drug, thereby preventing unintended delivery of drug and/or alerting a user that unintended delivery of drug may occur.
1. A method of automatically and periodically confirming that drug will not be delivered by an electrotransport drug delivery device when the device is in an off state while powered on, the method comprising:
determining if there is a current flowing between an anode and a cathode of the electrotransport drug delivery device when the electrotransport drug delivery device is in an off state while powered on, wherein the electrotransport drug delivery device includes an activation circuit that is configured to apply current between the anode and the cathode to deliver a drug when the device is in an on state and not deliver drug in the off state; and
triggering an indicator if there is a current flowing between the anode and cathode that is greater than an Output Current Off Threshold when the electrotransport drug delivery device is in an off state while powered on, wherein triggering an indicator comprises performing a device shutdown.
2. The method of claim 1 , further comprising repeating the determining step periodically while the activation circuit is in an off state.
3. The method of claim 1 , further comprising repeating the determining step at least once every 10 minutes while the activation circuit is in an off state and the device is powered on.
4. The method of claim 1 , wherein the Output Current Off Threshold is about 9 μA.
5. The method of claim 1 , wherein determining if there is a current flowing between the anode and cathode of the electrotransport drug delivery device comprises independently determining an anode voltage and a cathode voltage and comparing the potential difference between the anode voltage and cathode voltage to the threshold value.
6. The method of claim 5 , wherein the threshold voltage is 2.5 V.
7. The method of claim 5 , wherein the threshold voltage is 0.85 V.
8. The method of claim 1 , wherein determining if there is a current flowing between the anode and cathode of the electrotransport drug delivery device comprises independently connecting a reference voltage source and a sense resistor with each of the anode and cathode to determine the potential difference between the anode voltage and cathode voltage.
9. The method of claim 1 , further comprising activating the activation circuit to enter the on state and applying current between the anode and the cathode after determining that no current above the Output Current Off Threshold is flowing between the anode and cathode while the electrotransport drug delivery device is in the off state.
10. The method of claim 1 , wherein triggering the indicator comprises illuminating a light and/or sounding an alarm on the device.
11. The method of claim 1 , further comprising measuring an Rsense resistance value of the electrotransport drug delivery device and verifying the accuracy of the Rsense resistance value.
12. The method of claim 1 , further comprising measuring the anode voltage and the cathode voltage using an ADC and calculating the voltage difference between the two.