Transdermal microneedles patch for painless and regulated drug delivery across skin

Abstract

Transdermal patch has become a promising way of drug delivery with low potential risks in past decades. Its simplicity, high portability, low cost, and minimal medical hazardous generation has led to high patient compliance and prevention of disease transmission. Typically, the reservoir and matrix systems allow drug diffusion through the skin barrier to microcirculation in the dermis. Undesirably, the unique closely packed cell structure of the stratum corneum inhibits the passage of a wide variety of drugs that are commonly used in current therapies. The concentration dependence of drug diffusion in conventional patch design also makes sustained delivery difficult. In view of this, recent research has put emphasis on bypassing the stratum corneum so as to allow more drugs to be delivered via the transdermal route. One major challenge is to achieve continuous drug delivery while keeping the device portable and simple. Herein, a microneedle-bonded transdermal patch with dimensions of less than 4 mm in height and 25 mm in diameter is developed, with the drug delivery rate controlled by a hydrogel actuator. The swelling rate of the hydrogel depends on the presence of swelling agent and number of PDMS coating on the hydrogel. Results show that the device can successfully deliver diverse drugs steadily in 8 hours using in vitro diffusion cell model. Furthermore, with insulin delivery to diabetic rats, the transdermal patch renders comparable glucose lowering effect as the intradermal injection.