Transdermal patch

Abstract: Transdermal patches are now widely used as cosmetic, topical and transdermal delivery systems. These patches represent a key outcome from the growth in skin science, technology and expertise developed through trial and error, clinical observation and evidence-based studies that date back to the first existing human records. This review begins with the earliest topical therapies and traces topical delivery to the present-day transdermal patches, describing along the way the initial trials, devices and drug delivery systems that underpin current transdermal patches and their actives. This is followed by consideration of the evolution in the various patch designs and their limitations as well as requirements for actives to be used for transdermal delivery. The properties of and issues associated with the use of currently marketed products, such as variability, safety and regulatory aspects, are then described. The review concludes by examining future prospects for transdermal patches and drug delivery systems, such as the combination of active delivery systems with patches, minimally invasive microneedle patches and cutaneous solutions, including metered-dose systems.

Abstract: Glucose-responsive insulin delivery systems that mimic pancreatic endocrine function could enhance health and improve quality of life for people with type 1 and type 2 diabetes with reduced β-cell function. However, insulin delivery systems with rapid in vivo glucose-responsive behaviour typically have limited insulin-loading capacities and cannot be manufactured easily. Here, we show that a single removable transdermal patch, bearing microneedles loaded with insulin and a non-degradable glucose-responsive polymeric matrix, and fabricated via in situ photopolymerization, regulated blood glucose in insulin-deficient diabetic mice and minipigs (for minipigs >25 kg, glucose regulation lasted >20 h with patches of ~5 cm2). Under hyperglycaemic conditions, phenylboronic acid units within the polymeric matrix reversibly form glucose–boronate complexes that—owing to their increased negative charge—induce the swelling of the polymeric matrix and weaken the electrostatic interactions between the negatively charged insulin and polymers, promoting the rapid release of insulin. This proof-of-concept demonstration may aid the development of other translational stimuli-responsive microneedle patches for drug delivery. A single removable transdermal patch bearing microneedles loaded with insulin and a non-degradable glucose-responsive polymeric matrix regulates blood glucose in insulin-deficient diabetic mice and minipigs.

Abstract: sult, most biotherapeutics are administered by hypodermic injection, which causes pain, can lead to infection, requires trained personnel, and often needs frequent, repeated injections for the patient. Consequently, there exists the need for a minimally invasive, self-administered delivery system for biomolecules. An attractive non-invasive option is the transdermal patch, which has been well-received for the delivery of nicotine, estrogens, and other drugs. [4] However, delivery across intact skin permits transport of small, lipophilic molecules only and excludes transport of biotherapeutics, due to their large size. This study presents a novel, hybrid delivery approach to achieve the delivery efficacy of injections and the safety and patient compliance of the patch. We designed and synthesized rapidly dissolving polymer needles of micrometer dimensions for the painless, self-administered delivery of biomolecules. In this design, the drug is encapsulated within polymer microneedles and, after insertion into the skin, the biocompatible polymer dissolves within minutes to release the encapsulated cargo, not requiring removal and leaving behind no biohazardous sharps. Previous work has shown that microscopically piercing the skin with micrometer-scale needles offers an effective and convenient alternative for the delivery of biomolecules because of the efficient delivery [5,6] , lack of pain [7–9] , ease of use, and the expected low cost of fabrication. Microneedles have been shown to be able to deliver proteins, DNA, and vaccines in vivo, using devices small enough to be integrated into a low-profile, self-administered patch. [9–11] To date, most microneedles have been made of silicon or metal [12,13] with little