Papers by Keyword: Transdermal Delivery

Abstract: Delivery of drugs through skin is obstructed by the excellent barrier properties of the outermost skin layer, the stratum corneum (SC). A strategy employing microneedles have recently emerged as a minimally invasive device for disrupting the SC structure and creating holes for molecules to pass through. Hollow-typed microneedles permit drug delivery which can be modulated over time via active delivery controlled by hand or pump. In this study, the potential of hollow microneedle for overcoming the outermost skin barrier and facilitating drug delivery into skin was investigated. Fluorescein isothiocyanate (FITC)-dextrans (4.3 kDa), FD-4, was used as a model large molecular compound. The effects of injection volume and formulation on drug release behavior from skin were determined. FD-4 was favorably loaded into the lower epidermis as well as the superficial dermis of the skin by a hollow microneedle. The release profiles of FD-4 were analyzed by Higuchi model based on Fick’s law of diffusion. The higher the volume of FD-4 solution injected, the faster the FD-4 release rate from skin. Liposome formulation exhibited no difference on drug release profiles compared with the solution. The results provide information for designing an effective hollow microneedles system.

Abstract: Various concentrations of either lidocaine or tetracaine, plus combinations of lidocaine and tetracaine were formulated into liposomes to improve topical anesthesia. The topical anesthetic effects of these liposomal mixtures of local anesthetics (Lipo-MLA) were then compared with those of EMLA (Eutectic Mixture of Local Anesthetics) and single local anesthetic liposomes using a pinprick test on healthy adult volunteers. The Lipo-MLA exhibited significantly improved anesthetic effects compared to the EMLA and single local anesthetic liposomes with a faster onset time of approximately thirty minutes and duration of at least four hours. A dermal toxicity study using rats revealed that Lipo-MLA was safe at greater than 2,000 mg/kg bodyweight.