RESEARCH ARTICLE – Pharmaceutics, Drug Delivery and Pharmaceutical Technology Erbium–Yttrium–Aluminum–Garnet Laser Irradiation Ameliorates Skin Permeation and Follicular Delivery of Antialopecia Drugs WOAN-RUOH LEE, 1,2 SHING-CHUAN SHEN, 1 IBRAHIM A. ALJUFFALI, 3 YI-CHING LI, 4,5 JIA-YOU FANG 4,6,7 1 Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan 2 Department of Dermatology, Taipei Medical University Shuang Ho Hospital, New Taipei City, Taiwan 3 Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia 4 Pharmaceutics Laboratory, Graduate Institute of Natural Products, Chang Gung University, Kweishan, Taoyuan, Taiwan 5 Chronic Diseases and Health Promotion Research Center, Chang Gung University of Science and Technology, Kweishan, Taoyuan, Taiwan 6 Chinese Herbal Medicine Research Team, Healthy Aging Research Center, Chang Gung University, Kweishan, Taoyuan, Taiwan 7 Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Kweishan, Taoyuan, Taiwan Received 21 April 2014; revised 24 July 2014; accepted 6 August 2014 Published online 3 September 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/jps.24143 ABSTRACT: Alopecia usually cannot be cured because of the available drug therapy being unsatisfactory. To improve the efficiency of treatment, erbium–yttrium–aluminum–garnet (Er–YAG) laser treatment was conducted to facilitate skin permeation of antialopecia drugs such as minoxidil (MXD), diphencyprone (DPCP), and peptide. In vitro and in vivo percutaneous absorption experiments were carried out by using nude mouse skin and porcine skin as permeation barriers. Fluorescence and confocal microscopies were used to visualize distribution of permeants within the skin. Laser ablation at a depth of 6 and 10 m enhanced MXD skin accumulation twofold to ninefold depending on the skin barriers selected. DPCP absorption showed less enhancement by laser irradiation as compared with MXD. An ablation depth of 10 m could increase the peptide flux from zero to 4.99 and 0.33 g cm −2 h −1 for nude mouse skin and porcine skin, respectively. The laser treatment also promoted drug uptake in the hair follicles, with DPCP demonstrating the greatest enhancement (sixfold compared with the control). The imaging of skin examined by microscopies provided evidence of follicular and intercellular delivery assisted by the Er–YAG laser. Besides the ablative effect of removing the stratum corneum, the laser may interact with sebum to break up the barrier function, increasing the skin delivery of antialopecia drugs. The minimally invasive, well-controlled approach of laser-mediated drug permeation offers a potential way to treat alopecia. This study’s findings provide the basis for the first report on laser-assisted delivery of antialopecia drugs. C  2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 103:3542–3552, 2014 Keywords: alopecia; minoxidil; diphencyprone; peptide; laser; absorption; percutaneous; skin; macromolecular drug delivery INTRODUCTION Alopecia is known as hair loss on the scalp because of an androgenetic process (androgenetic alopecia) or an inflamma- tory process (alopecia areata). The prevalence of androgenetic alopecia in Caucasian men is 96%. 1 On the contrary, alope- cia areata affects 2.1% of the population. 2 Minoxidil (MXD) is developed for the treatment of both alopecia types. This drug at a 5% dose is the first-line topical therapy for androgenetic alopecia. 3 It can reduce baldness by the mechanisms of va- sodilation, enhanced proliferation, and angiogenesis. Diphen- cyprone (DPCP) is a contact allergen for topical immunother- apy of alopecia areata. Alopecia treatment by drugs is always inefficient. The effect of MXD is not permanent, and the treat- ment cessation contributes to hair loss in 4–6 months. 4 More- over, contact dermatitis occurs in 6% of patients receiving 5% MXD. 5 A lag time of 3 months from initiation of treatment to initial hair growth is observed for DPCP with a success rate of only 50%. The adverse effects of DPCP occur in 24% of patients. 6 Recent advances in biotechnology have developed macromolecules and nanoparticles for alopecia therapy. These Correspondence to: Jia-You Fang (Telephone: +886-3-2118800; Fax: +886-3- 2118236; E-mail: fajy@mail.cgu.edu.tw) Journal of Pharmaceutical Sciences, Vol. 103, 3542–3552 (2014) C  2014 Wiley Periodicals, Inc. and the American Pharmacists Association include growth factors, proteins, genes, and fullerenes. 7–9 Abun- dant investigations document the use of peptides to counter the effect of alopecia. These include soymetide-4, 10 formyl– methyonyl–leucyl–phenylalanine, 11 prolactin, 12 and calcitonin gene-related peptide. 13 These biologics, however, show unsatis- factory results in treating alopecia because of their instability and molecular size, which is too large to penetrate the skin. Efficient topical drug delivery is challenging because of the formidable barrier function of the stratum corneum (SC). SC re- moval by tape-stripping, mechanical abrasion, and laser treat- ment has shown to be effective for promoting drug permeation via the skin. 14 The approaches of tape-stripping and abrasion are limited and lack reproducibility because of the poor abil- ity to control the SC ablation level. Laser treatment can pre- cisely and selectively remove SC in a controlled and noncon- tact manner. 15 The duration of laser irradiation is in the range of nano- to microseconds, indicating a quick operation for en- hancing drug absorption. 16 It has been shown that the ablative lasers can increase topical delivery of small molecule drugs, macromolecules, and nanoparticles. 17,18 The improvement of antialopecia drug delivery for achieving efficacious therapy is urgent. We sought to evaluate the impact of ablative laser treat- ment on cutaneous delivery of antialopecia drugs, including MXD, DPCP, and peptide. Hair follicles are the main target for these drugs in treating hair loss. The follicular openings of 3542 Lee et al., JOURNAL OF PHARMACEUTICAL SCIENCES 103:3542–3552, 2014