Microneedles: an emerging transdermal drug delivery system

Abstract

Objectives One of the thrust areas in drug delivery research is transdermal drug delivery systems (TDDS) due to their characteristic advantages over oral and parenteral drug delivery systems. Researchers have focused their attention on the use of microneedles to overcome the barrier of the stratum corneum. Microneedles deliver the drug into the epidermis without disruption of nerve endings. Recent advances in the development of microneedles are discussed in this review for the benefit of young scientists and to promote research in the area. Key findings Microneedles are fabricated using a microelectromechanical system employing silicon, metals, polymers or polysaccharides. Solid coated microneedles can be used to pierce the superficial skin layer followed by delivery of the drug. Advances in microneedle research led to development of dissolvable/degradable and hollow microneedles to deliver drugs at a higher dose and to engineer drug release. Iontophoresis, sonophoresis and electrophoresis can be used to modify drug delivery when used in concern with hollow microneedles. Microneedles can be used to deliver macromolecules such as insulin, growth hormones, immunobiologicals, proteins and peptides. Microneedles containing 'cosmeceuticals' are currently available to treat acne, pigmentation, scars and wrinkles, as well as for skin tone improvement. Summary Literature survey and patents filled revealed that microneedle-based drug delivery system can be explored as a potential tool for the delivery of a variety of macromolecules that are not effectively delivered by conventional transdermal techniques.

Microneedles for drug delivery: trends and progress

“…It can be seen that there is a considerable amount of MN patens taken out on hollow MNs. This may be due to the fact that hollow MNs have the advantage of delivering a higher dosage in comparison to other methods (Bariya et al, 2011).…”

“…They are small arrays of needles that are generally less than 1 mm in length (Aggarwal et al, 2009;Bariya et al, 2012;Desale et al, 2012;Shikida, 2012). There are multiple MN designs that have been created over the past decade.…”

“…There are multiple MN designs that have been created over the past decade. They can be categorized into two types, solid or hollow MNs (Bariya et al, 2011). The materials that have been used to fabricate them range from metal (Choi et al, 2013), glass, silicon (Wei-Ze et al, 2010) and biodegradable polymers (polydimethylsiloxane) (Chu & Prausnitz, 2011;Bediz et al, 2013) and silk fibroin (Tsioris et al, 2012).…”

Potential of biodegradable microneedles as a transdermal delivery vehicle for lidocaine

“…Such a test can be done using an axial load testing station which relies on gradually moving the microneedles into a block of metals (e.g. aluminium) until needle breakages are evident (Bariya et al 2011). A measured section of the metal block contains a pre-determined thickness of skin attached by dual sticky tape and the other section of the block is connected to a compression cell containing microneedles and motorised actuator.…”

“…However, the manufacturing processes of casting and hot embossing are common for biodegradable microneedles, which are discussed briefly. In the casting process, a master template is fabricated to develop a mould template for a molten drug formula to fill the mould contours, solidify via favourable temperature and pressure conditions and finally removal of the mould from the solidified drug formula (Bariya et al 2011). Poly-dimethyl-siloxane (PDMS) is an ideal material for replica moulding of microneedles because of its non-toxicity, elastic properties and low cost (Saliterman 2006;) and as such, it has been used in many studies.…”