The dosage parameters....

What’s the dose?

Four parameters:

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·       The selection of drug ions- based on the therapeutic effect that is desired for any given pathology. For example when goals are to decrease pain or inflammation then the drugs selected will be either analgesic and/or anti-inflammatory.

·         Polarity of the aqueous solution of the drug being used- for transport to occur at the electrode/skin interface the negatively charged drug ion must be positioned under the negative pole (cathode). Similarly the positively charged drug ions must be placed under the positive pole (anode). Tap water has a double polarity therefore positioning is not critical however it is recommended to inverse the current midway through treatment to ensure equal phoresis of both ions in the skin.

·         Chemical concentration and volume of ionic drug solution delivered- literary consensus that the concentration range from 2-5% aqueous solution. The solution of the drug should contain low concentrations as it has been found that the amount of drug delivered is not increased with the use of higher concentrations. The volume of drug aqueous solution contained in the electrode patch are dependent on the filling capacity of the individual reservoir and is indicated by the manufacturer

·         The dose used (D)- proportional to the current magnitude used (A) and the total application duration (T)

o   D (mA.min)= A (mA) X T (min)

Drug doses range between 1 and 80 mA.min with a maximum available current amplitude of 4mA. These are delivered using portable stimulators and wearable patches.

·         Portable stimulators- constant current (CC) stimulators maximum DC amplitude reaches 4 mA. Practitioners are able to program the dosage and set the desired amplitude where duration can be manually or automatically controlled.

·         Patches- constant voltage sold either 40 mA.min or 80 mA.min worn for 12hrs and 24hrs respectively. These differences account for current fluctuations due to soft tissue impedance changes; however with the use of patches the practitioner has no control over the amplitude settings.

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In our next blog we will discuss the safety parameters before the application of iontophoresis within your clinic.


REFERENCES
Belanger, A. (2010). Therapeutic Electrophysical Agents: Evidence Behind Practice (Second Ed.) Philadelphia, PA: Lippincott, Williams and Wilkins.