Transdermal delivery through Radio-Frequency-MicroChannels (RF-MCs) was proven to be a promising delivery method for hydrophilic drugs and macromolecules that must be injected. An important issue in assessing this technology is the life span of the microchannels (MCs). The time window in which the MCs remain open affects the delivery rate and determine the effective delivery duration. The present work focused on the characterization of the ViaDor-MCs recovery and closure process by measurements of transepidermal water loss (TEWL) before and after the formation of MCs, evaluation of the delivery window, and assessment of skin histology. Testosterone-cyclodextrin complex was used as the model drug for evaluation of the transdermal delivery. In-vitro permeation system and in-vivo guinea pig animal model were used in the delivery studies. Our findings demonstrate the recovery process of MCs created by the RF ablation technology. The observed gradual skin recovery affected the transdermal delivery rate. A significant transdermal delivery was shown up to 24 hrs post device application suggesting that an extended delivery of water soluble drugs, including macromolecules, is possible. The histology assessments demonstrated repair and healing of the induced MCs indicating that the RF micro-channeling technology is minimally invasive, transient in nature with no resulting skin trauma.
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