Microneedles: Characteristics, Materials, Production Methods and Commercial Development

Abstract

Although transdermal drug delivery systems (DDS) offer numerous benefits for patients, including the avoidance of both gastric irritation and first-pass metabolism effect, as well as improved patient compliance, only a limited number of active pharmaceutical ingredients (APIs) can be delivered accordingly. Microneedles (MNs) represent one of the most promising concepts for effective transdermal drug delivery that penetrate the protective skin barrier in a minimally invasive and painless manner. The first MNs were produced in the 90s, and since then, this field has been continually evolving. Therefore, different manufacturing methods, not only for MNs but also MN molds, are introduced, which allows for the cost-effective production of MNs for drug and vaccine delivery and even diagnostic/monitoring purposes. The focus of this review is to give a brief overview of MN characteristics, material composition, as well as the production and commercial development of MN-based systems.

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

“…Consequently, many preclinical and clinical trials have been conducted that involve polymeric MN devices. In the fabrication of an MN master template, it is required to have thousands of USD and the access and arrangement of facilities such as a clean room and photo-etching equipment for the implementation of techniques such as deep-reactive ion-etching, laser-etching, and anisotropic wet etching [ 296 , 297 ]. Hurdles are encountered along the way of clinical translation of this device [ 298 ].…”

3D Printing—A “Touch-Button” Approach to Manufacture Microneedles for Transdermal Drug Delivery

“…Usually, they deliver drugs transdermally by one of three mechanisms, which include “ poke and patch ”, “ poke and release ”, and “ coat and poke ” approaches [ 71 ]. The “ poke and patch ” is a mechanism of applying MNs to pierce the SC to create transient aqueous microchannels on the skin surface before the application of a drug-loaded patch or other topical drug formulation, which can be in the form of a gel, ointment, cream, solution, foam, lotion, or spray ( Figure 1 B) [ 8 , 14 , 58 ]. Then, a drug from a formulation or patch permeates through these microchannels by passive diffusion directly into the dermis to reach systemic circulation [ 6 , 14 ], improving the drug permeability up to four orders of magnitude [ 14 , 67 ].…”

“…Microneedles (MNs) represent skin-friendly puncturing devices of microscale dimensions [ 5 ] that are designed to efficiently and painlessly bypass the outermost layer of the skin, the stratum corneum (SC), which acts as a barrier for transdermal penetration of APIs, in particular for those with log p values below 1 and greater than 3 [ 6 ], by forming microchannels and thus releasing the drug into the skin’s microcirculation [ 7 , 8 ]. The concept of MNs dates back to the 1970s when Gerstel and Place filled out the patent form (the current assignee is Alza Corporation) [ 9 ].…”

“…To meet all requirements for the non-invasive application and efficient drug delivery to the systemic circulation, a successful MN system must be produced by a manufacturing method that guarantees accurate, reproducible, robust, and precise production of MN in the micrometer range [ 8 , 10 ]. To date, manufacturing strategies for MN include techniques such as lithography [ 11 ], electrochemical and photochemical etching [ 12 ], laser cutting [ 13 ], laser ablation [ 14 ], metal electroplating [ 15 ], laser micromachining, injection molding [ 16 ], and micromolding [ 17 ].…”

Antihypertensives’ Rock around the Clock

“…Microneedles (MNs) are very interesting and promising for future hypertension therapy. MNs are collections of micrometer-sized needles that can aid the transdermal drug delivery by painlessly and minimally invasively penetrating the protective skin barrier [109]. Of five types of MNs (hollow, solid, coated solid, dissolving, hydrogel [109]), only solid and dissolving MNs have been used to develop a new therapeutic strategy for hypertension.…”