Characterization of the Effects of Dermal Tattoo Machine Delivery versus Conventional Topical Delivery of Croton Oil and Hetter Phenol–Croton Oil Formula

BACKGROUND Examples of deep chemical peels include Baker-Gordon (2.1% croton oil/49.3% phenol) and Hetter formulas (1.6% croton oil/35% phenol). Depth of penetration of deep chemical peels is variable, especially when applying with a cotton-tipped applicator. OBJECTIVE Assess microscopic depth of injury and collagen production with the Hetter formula and pure croton oil using drug tattooing technique versus topical application. MATERIALS/METHODS Using a porcine model, pure croton oil and Hetter formula were tattooed using the Cheyenne Hawk Pen 23-Magnum SE. The microscopic depth of injury (evaluated through depth of penetration of India ink) and collagen production were evaluated with hematoxylin and eosin–stained biopsies performed 24 hours, 7 days, and 21 days postprocedure. Herovici collagen stain was used to differentiate between new type III collagen and mature type I collagen. RESULTS Intradermal delivery of Hetter formula and pure croton oil showed deeper penetration and more neocollagenesis 21 days postprocedure compared with topical delivery. CONCLUSION Drug tattooing of chemical peels can be used to ensure deeper dermal penetration and more neocollagenesis. Future studies using human subjects are needed to assess depth of penetration of chemical peel formulas for a variety of clinical indications, including scarring, dyspigmentation, and photoaging.