Dissolving Microneedles Developed in Association with Nanosystems: A Scoping Review on the Quality Parameters of These Emerging Systems for Drug or Protein Transdermal Delivery

Abstract

The largest organ of the body provides the main challenge for the transdermal delivery of lipophilic or high molecular weight drugs. To cross the main barrier of the skin, the stratum corneum, many techniques have been developed and improved. In the last 20 years, the association of microneedles with nanostructured systems has gained prominence for its versatility and for enabling targeted drug delivery. Currently, the combination of these mechanisms is pointed to as an emerging technology; however, some gaps need to be answered to transcend the development of these devices from the laboratory scale to the pharmaceutical market. It is known that the lack of regulatory guidelines for quality control is a hindrance to market conquest. In this context, this study undertakes a scoping review of original papers concerning methods applied to evaluate both the quality and drug/protein delivery of dissolving and hydrogel-forming microneedles developed in association with nanostructured systems.

Formulation and Evaluation of Niosomal Alendronate Sodium Encapsulated in Polymeric Microneedles: In Vitro Studies, Stability Study and Cytotoxicity Study

“…Numerous strategies have been developed in order to penetrate the skin’s primary barrier. Due to its adaptability and capacity for sustained release, the integration of MNs with nano-systems has become more popular during the past 20 years [ 63 , 64 ]. Therefore, integrating physical and chemical technology provides a significant improvement in drug delivery.…”

Rapidly Dissolving Microneedles for the Delivery of Steroid-Loaded Nanoparticles Intended for the Treatment of Inflammatory Skin Diseases

“…Despite the significant value of these skin-simulant models for the characterization of MNs, there are some limitations to be considered, such as the lack of pharmacopeial standards for MN-based products [ 49 ], the absence of validation of in vitro methods to characterize the dissolution and release profiles of therapeutics from MNs containing nanosystems [ 24 ], and the differences between the human skin and skin simulants used in this study, like their composition and water content [ 42 , 50 , 51 , 52 ].…”

“…After 5 min, the weights were removed, and morphological changes were evaluated by a HAYEAR 4K UHD microscope camera. The rate of change of the height (µm) of the MNs was calculated and plotted as the percentage of reduction in MN height [ 23 , 24 ].…”

Preparation and characterization of flexible furosemide-loaded biodegradable microneedles for intradermal drug delivery

“…The drug release experiment was performed at 37 °C to simulate the internal body temperature where the drug is presumably released from the microneedles. [26][27][28] FUR concentrations were determined following suitable dilution using a UV-vis spectrophotometer at a wavelength of 277 nm. 29 The concentrations of FUR calibration curve in PBS ( pH 7.4) ranged from 0 to 30 μg mL −1 (Fig.…”

“…In the present study, the lower counterface was made of a flat block of aluminum (Young's Modulus, E ≈ 69 GPa) for the reference test and ex vivo chicken skin, obtained from a local slaughter house, for the penetration test. 26,31,32 The MN samples were glued to a hard support on a passive self-aligning system based on the principle of two free rotation axes to guarantee a full flat-on-flat contact between the mating surfaces. The self-aligning system is attached to a motorized linear actuator (A-LAR300APC-01, US) that can move to bring the mating surfaces in contact under a predefined constant loading velocity to reach the desired normal load and then, after a predefined waiting dwell time under the loaded state, the translation stage is withdrawn opposite to the normal direction.…”