Microneedles-mediated drug and vaccine delivery

Several decades past, the concept of microneedles was laid down but turned out to be the area under research in the mid 1990’s due to their production via microfabrication technology. A plethora of troubles has been associated with injection by needle-and-syringe-based delivery of drug and vaccine comprising patient compliance and acceptability, pain of needles, needlestick injuries, requirement for trained personnel to accurately reconstitute and withdraw drug and correctly inject it to specified site. Microneedles are an array of microscopic needles or modest invasive devices which painlessly penetrate the skin barrier for drug and vaccine delivery. Microfabrication technique for microneedles production involves the manufacture of microneedles-integrated drug/vaccine delivery systems, namely, microneedles coated with drug that dissolves off in the skin, encapsulation of drug in polymer microneedles that dissolve completely in the skin, and hollow microneedles for drug infusion into the skin. As per the research literatures available, wide range of drugs and vaccines had been successfully loaded into microneedles for their significant therapeutic effect. This concept of microneedles is an amalgamation of hypodermic needles and transdermal patches. Microneedles comprise sharp tips which disrupt the skin but unable to damage deeper tissue due to microscopic structure and size. The characteristic of microneedles includes ruggedness, controlled drug delivery, and easy penetration into skin. The construction material for microneedles includes glass, silicone (of brittle nature), metals such as stainless steel, solid or coat of gold over nickel, palladium, cobalt and platinum, and biodegradable polymers. Marketed formulations based on microneedles are AdminPenTM, AdminPatchTM, etc. Several investigation reports corroborated that microneedles ought to be significant vehicles for enhancing the deep penetration into systemic circulation and facilitating a painless and safest route of drug delivery. Exultant utilization of microneedles is totally based on function of devices in terms of microneedles insertion, possible infusion into skin, skin recovery after microneedle removal, and on patient outcomes. These mildest invasive devices are gradually attaining significance and henceforth would meet the requirements of essential devices for controlled drug release.