Abstract
BackgroundTwo commercially available microneedle rollers with a needle length of 200 μm and 300 μm were selected to examine the influence of microneedle pretreatment on the percutaneous permeation of four non-steroidal anti-inflammatory drugs (diclofenac, ibuprofen, ketoprofen, paracetamol) with different physicochemical drug characteristics in Franz-type diffusion cells. Samples of the receptor fluids were taken at predefined times over 6 hours and were analysed by UV–VIS high-performance liquid-chromatography. Histological examinations after methylene blue application were additionally performed to gather information about barrier disruption.ResultsDespite no visible pores in the stratum corneum, the microneedle pretreatment resulted in a twofold (200 μm) and threefold higher (300 μm) flux through the pretreated skin samples compared to untreated skin samples for ibuprofen and ketoprofen (LogKow > 3, melting point < 100°C). The flux of the hydrophilic compounds diclofenac and paracetamol (logKow < 1, melting point > 100°C) increased their amount by four (200 μm) to eight (300 μm), respectively.ConclusionCommercially available microneedle rollers with 200–300 μm 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.
Highlights
Two commercially available microneedle rollers with a needle length of 200 μm and 300 μm were selected to examine the influence of microneedle pretreatment on the percutaneous permeation of four non-steroidal anti-inflammatory drugs with different physicochemical drug characteristics in Franz-type diffusion cells
In skin samples pretreated with the 300 μm microneedles a significant higher permeation was found than in the untreated skin samples, by which the maximum flux (Jmax) and the Papp-value are up to 3-fold to 7-fold and 8-fold higher in the microneedle treated skin samples (Table 1) and result in higher recoveries after microneedle pretreatment
The correlation of physicochemical drug characteristics with the enhancement of the permeation reveals that substances with low lipophilicity (R2 = 0.73) and high melting points (R2 = 0.76) benefit from microneedle application, while there is no correlation of the microneedle pretreatment to the molecular weight (R2 = 0.01)
Summary
Two commercially available microneedle rollers with a needle length of 200 μm and 300 μm were selected to examine the influence of microneedle pretreatment on the percutaneous permeation of four non-steroidal anti-inflammatory drugs (diclofenac, ibuprofen, ketoprofen, paracetamol) with different physicochemical drug characteristics in Franz-type diffusion cells. Histological examinations after methylene blue application were performed to gather information about barrier disruption. 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, patches and microneedles have been developed for a convenient and effective transdermal drug delivery [7]. Unlike skin abrasion the microneedle application represents a safe, efficient and controllable alternative for increasing transdermal drug delivery [11]
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