Hard polymeric porous microneedles on stretchable substrate for transdermal drug delivery

Abstract

Microneedles offer a convenient transdermal delivery route with potential for long term sustained release of drugs. However current microneedle technologies may not have the mechanical properties for reliable and stable penetration (e.g. hydrogel microneedles). Moreover, it is also challenging to realize microneedle arrays with large size and high flexibility. There is also an inherent upper limit to the amount and kind of drugs that can be loaded in the microneedles. In this paper, we present a new class of polymeric porous microneedles made from biocompatible and photo-curable resin that address these challenges. The microneedles are unique in their ability to load solid drug formulation in concentrated form. We demonstrate the loading and release of solid formulation of anesthetic and non-steroidal anti-inflammatory drugs, namely Lidocaine and Ibuprofen. Paper also demonstrates realization of large area (6 × 20 cm2) flexible and stretchable microneedle patches capable of drug delivery on any body part. Penetration studies were performed in an ex vivo porcine model supplemented through rigorous compression tests to ensure the robustness and rigidity of the microneedles. Detailed release profiles of the microneedle patches were shown in an in vitro skin model. Results show promise for large area transdermal delivery of solid drug formulations using these porous microneedles.

Fabrication and Characterization of Porous Microneedles for Enhanced Fluid Injection and Suction: A Two‐Photon Polymerization Approach

“…The load was divided by the number of MNs to identify the maximum load one MN can withstand, and the porous (open tip) MN could handle a compression force of 0.596 N per MN, comparable to that found in the literature. [ 32,42–44 ] The hollow MN could withstand a force of 0.576 N and the porous (closed tip) a force of 0.556 N. This proves that when using this design and fabrication technique, the additional pores do not significantly affect the mechanical stability of the MN.…”

“…[35] Although there are multiple advantages to porous MNs, they lack mechanical stability. [12,38,39] Silicon porous MNs have been tested, but as silicon is already brittle, making it porous decreased its mechanical stability further. [13] Shirkhanzadeh discussed coating solid MNs with a porous ceramic material, but that method can only serve to increase the surface area and does not allow for internal fluid flow.…”

Microneedle-based ocular drug delivery systems – recent advances and challenges

“…Upon application, the drug dissolves in a physiological fluid and, in this form, can permeate to the deeper tissues [ 161 ]. In the techniques involving polymers applied to obtain solid microneedles, the drug may be dissolved [ 162 – 163 ] or suspended [ 164 ] in the polymer or monomer solution. In the manufacturing of more complex systems, with the active ingredient incorporated in a specific compartment of a microneedle, more complex procedures involving both drug-loaded and drug-free solutions may be employed [ 165 ].…”

Fast Customization of Hollow Microneedle Patches for Insulin Delivery

“…Dissolving microneedles are made of dissolvable materials and release the drugs after microneedle dissolution. Porous microneedles release the drug into the skin through the pores of the needle body, such as swelling hydrogel-forming microneedle[ 1 ], and other porous microneedles[ 2 - 4 ]. HMNs can be regarded as scaled-down traditional hypodermic needles with a micron-level length and diameter.…”