Microneedle integrated transdermal patch for fast onset and sustained delivery of lidocaine.

Lidocaine as an analgesic is of particular interest in both acute and chronic pain conditions and is used via injections or transdermal patches. While injections are associated with problems such as patient incompliance, topical administration of lidocaine using patches is less efficient due to variability of drug absorption among individuals, slower drug permeation through the skin, and hence a resultant undesirable delay in analgesic effects. To address this clinical problem, we developed a microneedle integrated transdermal patch (MITP), using a photolithography based process, in which microneedles create micrometer-sized channels in the skin to deliver lidocaine rapidly, while the reservoir patch holding the bulk of the drug enables higher drug loading and carries on to release the drug for prolonged periods. We demonstrated a new approach of drug delivery using microneedles, where drugs diffuse out of microneedles through the porous channels left by dissolving drug particles. MITP was shown to be able to encapsulate up to 70 mg of lidocaine. In vitro permeation through rat skin demonstrated that MITP delivered a significantly higher amount of lidocaine than a commercial patch and with a faster onset of drug permeation.