Coated microneedle with multilayer structure, method for preparing the same and microneedle patch comprising coated microneedle

A coated microneedle with a multilayer structure, comprising a base, a needle tip on the base, and a functional coating on the needle tip,

• wherein the functional coating comprises:
• (i) a content comprising a water-soluble polymer material and an active ingredient, and
• (ii) a sustained-release layer that completely wraps the content and directly contacts the needle tip,
• wherein the sustained-release layer is formed by a process comprising:
• (a) applying and drying a first portion of a sustained-release precursor solution on the needle tip to form a bottom swelling layer, wherein the sustained-release precursor solution comprises a delayed crosslinked sodium alginate system comprising a calcium source in a chelating state, a glucolactone and a carrier mixed in water,
• (b) applying and drying the content on the bottom swelling layer, and
• (c) applying and drying a second portion of the sustained-release precursor solution over the content to completely encapsulate the content within the sustained-release layer;
• wherein the calcium source gradually releases Ca2+ ions upon slow decomposition of the glucolactone in water to form crosslinking with the carrier during and after drying;
• and
• wherein the sustained-release layer, after insertion into skin, swells with water and delays dissolution of the content to provide sustained release of the active ingredient over at least 24 hours.

A coated microneedle with a multilayer structure, comprising

• a base, a needle tip on the base, and a functional coating on the needle tip,
• wherein the functional coating comprises:
• (i) a content comprising a water-soluble polymer material and an active ingredient, and
• (ii) a sustained-release layer that completely wraps the content and directly contacts the needle tip,
• wherein the sustained-release layer is formed by a process comprising:
• (a) applying and drying a first portion of a near-neutral chitosan solution on the needle tip to form a bottom swelling layer,
• (b) applying and drying the content on the bottom swelling layer, and
• (c) applying and drying a second portion of the near-neutral chitosan solution over the content to completely encapsulate the content;
• wherein the sustained-release layer, after insertion into skin, swells with water and delays dissolution of the content to provide sustained release of the active ingredient over at least 24 hours.