%0 Journal Article %T Microneedle pretreatment enhances the percutaneous permeation of hydrophilic compounds with high melting points %A Jessica Stahl %A Mareike Wohlert %A Manfred Kietzmann %J BMC Pharmacology and Toxicology %D 2012 %I BioMed Central %R 10.1186/2050-6511-13-5 %X Despite no visible pores in the stratum corneum, the microneedle pretreatment resulted in a twofold (200£¿¦Ìm) and threefold higher (300£¿¦Ìm) flux through the pretreated skin samples compared to untreated skin samples for ibuprofen and ketoprofen (LogKow£¿>£¿3, melting point£¿<£¿100¡ãC). The flux of the hydrophilic compounds diclofenac and paracetamol (logKow£¿<£¿1, melting point£¿>£¿100¡ãC) increased their amount by four (200£¿¦Ìm) to eight (300£¿¦Ìm), respectively.Commercially available microneedle rollers with 200¨C300£¿¦Ìm long needles enhance the drug delivery of topically applied non-steroidal anti-inflammatory drugs and represent a valuable tool for percutaneous permeation enhancement particularly for substances with poor permeability due to a hydrophilic nature and high melting points.The topical transdermal administration of systemically active drugs represents a convenient alternative to systemic administration via oral route in both humans and animals with many advantages like the avoidance of the first-pass hepatic metabolism, enzymatic degradation and side effects in the gastro-intestinal tract. The outmost layer of the epidermis, the stratum corneum, plays a key role in the skin barrier concerning the intrusion of foreign substances from the environment and transepidermal water loss (TEWL) [1]. It is composed of keratin containing corneocytes embedded in a lipid rich matrix, which acts like a kit-substance and mainly comprises ceramides, free fatty acids and cholesterol [2]. Substances applied onto the skin surface, thereby, can pass this complex structure by different routes. Although the tortuous pathway between the corneocytes is likely to be the main route through the stratum corneum, it can be bypassed by orifices and glands, both of which can account for a large part of the body surface [1]. However, transdermal drug delivery is severely limited to a small percentage of drugs due to physicochemical drug characteristics and barrier properties of the skin. Therefore, %K Transdermal drug delivery %K Microneedles %K logKow %K Melting point %K Non-steroidal anti-inflammatory drug %K In vitro permeation study %K Physical penetration enhancement %U http://www.biomedcentral.com/2050-6511/13/5