Electrically Assisted Transdermal Therapeutic Devices- An Overview

Skin penetration enhancement techniques have been developed to improve bioavailability and increase the range of drugs for which topical and transdermal delivery is a viable option. This review describes enhancement techniques based on Enhancement via modification of the stratum corneum by electrically-based rate controlled Transdermal drug delivery System technologies. These methods involve the use of external energy to act as a driving force and/or act to reduce the barrier nature of the Stratum Cornium in order to enhance permeation of drug molecules in to the skin. Recent progress in these technologies has occurred as a result of advances in precision engineering (bioengineering), computing, chemical engineering and material sciences, which have all helped to achieve the creation of miniature, powerful devices that can generate the required clinical response. A number of electrical methods of penetration enhancement have been evaluated. These include Iontophoresis (driving charged molecules into the skin by a small direct current approximately 0.5 mA/cm2), Sonophorsis and Phonophoresis (cavitation caused by low frequency ultrasound energy increases lipid fluidity), Electroporation (application of short micro- to millisecond electrical pulses of approximately 100-1000 V/cm to create transient aqueous pores in lipid bilayers), Photomechanical waves (laser-generated stress waves reported to cause a possible transient permeabilisation of the stratum corneum) and Magnetophoresis (skin penetration can be enhanced by applying magnetic field).