What is the Difference Between Iontophoresis and Sonophoresis?

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Iontophoresis and sonophoresis are both drug delivery methods used to enhance the absorption of substances through the skin. However, they differ in the way they achieve this and in their applications.

Iontophoresis:

  • Uses a voltage gradient on the skin to deliver drugs into the body.
  • Primarily transports ions and some molecules through the process of electroendoosmosis.
  • Transports drugs only across the outermost layer of the epidermis (stratum corneum).
  • Commonly used in the treatment of various conditions, such as muscle soreness, tendonitis, and bursitis.

Sonophoresis:

  • Uses low-frequency ultrasound (20-150 kHz) to enhance drug absorption.
  • Involves the delivery of molecules.
  • Transports drugs across the epidermis, dermis, and skin appendages.
  • Widely used by physiotherapists and has a greater depth of penetration than iontophoresis, with ultrasound waves reported to penetrate up to 4 to 6 cm into the tissues.

Both techniques can cause unwanted skin conditions such as pain and irritation. In some cases, a combination of iontophoresis and sonophoresis has been shown to result in greater enhancement and increased safety in reducing individual enhancer side effects.

Comparative Table: Iontophoresis vs Sonophoresis

Here is a table comparing the differences between iontophoresis and sonophoresis:

Feature Iontophoresis Sonophoresis
Description A drug delivery method that uses a voltage gradient on the skin to deliver drugs into the body. A drug delivery method that uses ultrasound to deliver drugs into the body.
Mechanism Active transport of drugs due to an applied electric field. Drug delivery enhanced by ultrasonic energy.
Energy Source Electric current. Ultrasonic energy.
Electrodes Involves cathode and anode electrodes. No electrodes involved.
Permeability Electric field can increase the permeability of the skin. Ultrasound can enhance skin permeability.
Frequency Effective at low frequencies (less than 100 kHz). Can be used with various ultrasound frequencies.
Uses Widely used in hospitals to deliver drugs through the skin. Gaining popularity in clinical setups, but not as widespread as iontophoresis.
Advantages Non-invasive transdermal drug delivery technique, based on transfer of charged molecules. Minimally invasive, suitable for delivering large molecular weight drugs.
Drawbacks Limited to specific drug types and concentrations, potential skin irritation. Limited evidence on long-term safety and efficacy, potential for skin damage at high intensities.

Both iontophoresis and sonophoresis are popular drug delivery methods used in clinical setups, and they facilitate drug delivery through the skin. However, they differ in their mechanisms, energy sources, and applications. Iontophoresis uses an electric current and electrodes to deliver drugs, while sonophoresis employs ultrasound energy for the same purpose. Each method has its advantages and drawbacks, but they can be complementary modalities for drug delivery.