Micro to nanoneedles: a trend of modernized transepidermal drug delivery system.

The transdermal route of drug delivery is convenient, pain-free and follows controlled rate release pattern. However, many therapeutically active drugs cannot cross the stratum corneum effectively. Lipophilic drugs like nifedipine cross the outer skin barrier easily and polar drugs, such as epinephrine are ineffective in showing the same effect. Due to these reasons, advancements in drug delivery have taken place to deliver a wide range of drugs, especially macromolecules through the transdermal route and directly into systemic circulation bypassing hepatic metabolism and GIT degradation. So there is a need for advanced drug delivery systems like microneedles and nanoneedles through transdermal route. These tiny needles will also serve as non-toxic, safe and stable systems for advanced drug delivery. Thus, macro to nanoformulation is the fast emerging fields nowadays. These have additional advantages to transdermal patches, such as better penetration, permeation, controlled release and direct delivery to the cytoplasm.