Iontophoresis: An Introduction and History

An Introduction to Iontophoresis

Iontophoresis, or “electrically assisted transdermal drug delivery” is a method of delivery of ionic substances through the skin, which is assisted or enhanced with an electric charge. This current being delivered can be turned on and off hereby controlling the release of solutes through the skin. Iontophoresis is used by physiotherapists for the delivery of anti-inflammatory medication for the treatment of plantar fasciitis, bursitis and a plethora of other clinical indications (Khan et al, 2011). The substance being transferred through the skin enters the circulation through the capillaries. This is beneficial for administration of some drugs as it avoids first pass clearance by the liver, enzymes and acidic or basic substances in the gastrointestinal tract (Khan et al, 2011). Currently, handheld devices are popular for Iontophoresis treatment (see Figure 1).

Figure 1: Chattanooga Ionto Device (Chattanooga Ionto Device, n.d.).

In terms of the popularity of Iontophoresis, few drugs are delivered this way in comparison to other routes. However, its use is increasing at a projected rate of 12% per annum, with 35 active ingredients approved by the Food and Drug Administration in the United States and 16 active ingredients approved for use worldwide. In 2005, Iontophoresis had a market of $12.7B and this is projected to increase substantially to $31.5B by 2015 (Prausnitz, Mitragotri & Langer 2004).

History

Although currently the use of Iontophoresis is rapidly becoming widespread, the  technique has been centuries in the making. The first notable literature published was in 1747 by Giovanni Pivati. After applying an electric current to a scented plant in a sealed jar, the smell penetrated the container. It was not until the 1850’s when it was first suggested that the application of electric current could be used for medication delivery (Helmstadter, 2001). From that time, several different substances were experimented with for their affinity for transdermal delivery (see Table 1).

(Helmstadter, 2001)

Transdermal delivery of ionized drugs without the aid of electric current had previously been rarely used due to the slow rate of diffusion powered only by the concentration gradient. With the application of the current techniques of Iontophoresis, transdermal delivery of these drugs is now desirable (Wang et al., 2005).

A safe, reliable method of Iontophoresis was first introduced in the US in 1989, however was never successful. Since then, technology has caught up, with the development of new products entering the market and making the process compatible with more drugs, and broadening the clinical indications for use.

Principles of Iontophoresis

Iontophoresis involves two electrodes, the cathode and the anode (see Figure 2). For a drug that is negatively charged, the drug must be dissolved in a solution and loaded into the cathode (negatively charged electrode). This electrode should be placed directly over the lesion and the anode is then placed a few centimetres away on the skin (Khan et al., 2011). As the drug and the electrode in which it is loaded have a like charge, the drug will move through the stratum corneum (the outer layer of the epidermis) towards the anode. Drugs with neither a positive nor negative charge also move through the skin due to osmotic/electro-osmotic forces when a current is applied (Khan et al., 2011). 

Figure 2: Electrode placement and drug delivery (TCT Summary, n.d.).

The history has been covered in todays blog, next up we will discuss the dosage guidelines that need to be understood and adhered to during administration of iontohphoresis.

References

Wang, Y., Thakur, R., Fan, Q. & Michniak, B. (2005). Transdermal iontophoresis: combination strategies to improve transdermal iontophoretic drug delivery. European Journal of Pharmaceutics and Biopharmaceutics, 60(2), 179-191.

Chattanooga Ionto Device [Image] (n.d.). Retrieved from http://www.medicalsearch.com.au/Products/Chattanooga-Ionto-Device-47714

Khan, A., Yasir, M., Asif, M., Chauhan, I., Singh, A., Sharma, R., Singh, P., Rai, S. (2011). Iontophoretic drug delivery: history and applications. Journal of applied pharmaceutical science, 1(3), 11-24.

TCT Summary [Image] (n.d.). Retrieved from http://www.transcu.com/en/p02_1.html

Helmstadter, A. (2001). The history of electrically-assisted transdermal drug delivery. Pharmazie, 56(7), 583-587.

Prausnitz, M., Mitragotri, S. & Langer, R. (2004). Current status and future potential of transdermal drug delivery. Drug Discovery, 3(2), 115-124.