Characterisation of mechanical insertion of commercial microneedles

Abstract

The protection provided by the human skin is mostly attributed to the stratum corneum. However, this barrier also limits the range of molecules that can be delivered into and across the skin. One of the methods to overcome this physiological barrier and improve the delivery of molecules into and across the skin is via the use of microneedles. This work evaluates the mechanical insertion of two different commercially available microneedle systems, Dermapen® and Dermastamp TM . The influence of biaxial skin strain on the penetration of the two microneedle systems was evaluated ex vivo using a biaxial stretch rig. From the skin insertion study, it was apparent that for all levels of biaxial strain investigated, the Dermapen® required less force than the Dermastamp TM to puncture the skin. In addition, it was observed that the oscillating microneedle system, the Dermapen®, resulted in deeper skin insertion ex vivo in comparison to the Dermastamp™. The use of this new biaxial stretch rig and the ex vivo skin insertion depth study highlights that the oscillating Dermapen® required less force to perforate the skin at varying biaxial strain whilst resulting in deeper skin penetration ex vivo in comparison to the Dermastamp TM . Although the Dermapen® punctured the skin deeper than the Dermastamp TM , such difference in penetration did not influence the permeation profile of the model drug, imiquimod across the skin as evidenced from a 24-hour ex vivo permeation study.

Elucidating the Impact of Surfactants on the Performance of Dissolving Microneedle Array Patches

“…This is attributed to the inherent viscoelastic properties of both Parafilm M and skin, which resist microneedle penetration, resulting in incomplete microneedle insertion. 62 In the control formulation, consisting of either ibuprofen sodium or itraconazole with PVA and PVP, we observed that the microneedle insertion into ex vivo skin was significantly deeper ( p < 0.05) than that into Parafilm. This observation might be attributed to the mechanical properties of neonatal porcine skin and the Parafilm stack.…”

Bioinspired Rotation Microneedles for Accurate Transdermal Positioning and Ultraminimal-Invasive Biomarker Detection with Mechanical Robustness

“…Full-thickness foreleg skin samples were obtained from a freshly slaughtered pig (aged approximately 2–3 years), reared explicitly for food. To avoid altering the skin's biomechanical properties, full-thickness hairless skin was necessary [ 49 ]. About 5 mm thick subcutaneous adipose tissue was kept in skin samples as the support to be more accordant with the in vivo situation with the tissue support under the skin.…”

Translation of Polymeric Microneedles for Treatment of Human Diseases: Recent Trends, Progress, and Challenges

“…For transverse forces on the MN, a metal sonde with a 1 cm blunt can be used. To measure bend, the MN array is contained above the loading cell, using two aluminum blocks [ 199 ] and the sample then adds strength to the middle of the backplate [ 200 ].…”

“…However, the structure and pharmacological response in an animal model differs from humans [ 50 , 106 ]. The pharmacological and pharmacokinetic analyses aid in optimizing the design of MNs and drug delivery for better therapeutic effect [ 44 , 200 , 220 , 224 ].…”

“…Porcine Skin Cargo Delivery Tests. The amount of drug delivered from the MNs to the skin was assessed using Franz diffusion cells with abdominal porcine skin [ 44 , 153 , 200 , 223 ]. Collected Skin samples were then placed in a phosphate-buffered saline (PBS) (pH 7.4) system for 1 h, and the prepared MN patch is inserted into abdominal porcine skin (1000 μm thick) for 30 s to determine the diffusion rates and effectiveness into porcine skin [ 153 , 164 , 229 ].…”