Anyone ever heard of someone using microneedles to improve transdermal delivery? It seems promising and I noticed you can buy microneedle rollers OTC (although they are a bit expensive). There is a lot of info out there on this. I'm wondering if you used the roller on your application site then followed up with your transdermal carrier what type of absorption you would get.
I dont really see any absorption improvement numbers though. Here's some info:
1: Adv Drug Deliv Rev. 2004 Mar 27;56(5):581-7.Click here to read Links
Microneedles for transdermal drug delivery.
School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, GA 30332-0100, USA. firstname.lastname@example.org
The success of transdermal drug delivery has been severely limited by the inability of most drugs to enter the skin at therapeutically useful rates. Recently, the use of micron-scale needles in increasing skin permeability has been proposed and shown to dramatically increase transdermal delivery, especially for macromolecules. Using the tools of the microelectronics industry, microneedles have been fabricated with a range of sizes, shapes and materials. Most drug delivery studies have emphasized solid microneedles, which have been shown to increase skin permeability to a broad range of molecules and nanoparticles in vitro. In vivo studies have demonstrated delivery of oligonucleotides, reduction of blood glucose level by insulin, and induction of immune responses from protein and DNA vaccines. For these studies, needle arrays have been used to pierce holes into skin to increase transport by diffusion or iontophoresis or as drug carriers that release drug into the skin from a microneedle surface coating. Hollow microneedles have also been developed and shown to microinject insulin to diabetic rats. To address practical applications of microneedles, the ratio of microneedle fracture force to skin insertion force (i.e. margin of safety) was found to be optimal for needles with small tip radius and large wall thickness. Microneedles inserted into the skin of human subjects were reported as painless. Together, these results suggest that microneedles represent a promising technology to deliver therapeutic compounds into the skin for a range of possible applications.
PMID: 15019747 [PubMed - indexed for MEDLINE]
1: Front Biosci. 2008 Jan 1;13:1711-5.Click here to read Links
Microneedles for transdermal drug delivery: a minireview.
Vandervoort J, Ludwig A.
Laboratory of Pharmaceutical Technology and Biopharmacy, University of Antwerp, B-2610 Wilrijk, Belgium. Jo.email@example.com
The stratum corneum is the main barrier for transdermal drug transport. It could be bypassed by microneedles, which have a length of a few tens to a few hundreds of microns. They are usually arranged in arrays and can be used in several ways to enhance transdermal drug transport. Microneedles can be inserted into the skin in order to increase its permeability, after which the drug is applied (poke with patch). Drugs could also be coated onto the microneedles and be inserted into the skin (coat and poke). Hollow microneedles are used to inject drug solutions in to the skin. This review aims to discuss recently published in vivo and in vitro studies on microneedle aided transdermal drug delivery.
PMID: 17981662 [PubMed - in process]There is a lot more info out there...just curious if anyone thinks this could be effective...1: Pharm Res. 2004 Jun;21(6):947-52.Click here to read Links
Transdermal delivery of insulin using microneedles in vivo.
Martanto W, Davis SP, Holiday NR, Wang J, Gill HS, Prausnitz MR.
School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
PURPOSE: The purpose of this study was to design and fabricate arrays of solid microneedles and insert them into the skin of diabetic hairless rats for transdermal delivery of insulin to lower blood glucose level. METHODS: Arrays containing 105 microneedles were laser-cut from stainless steel metal sheets and inserted into the skin of anesthetized hairless rats with streptozotocin-induced diabetes. During and after microneedle treatment, an insulin solution (100 or 500 U/ml) was placed in contact with the skin for 4 h. Microneedles were removed 10 s, 10 min, or 4 h after initiating transdermal insulin delivery. Blood glucose levels were measured electrochemically every 30 min. Plasma insulin concentration was determined by radioimmunoassay at the end of most experiments. RESULTS: Arrays of microneedles were fabricated and demonstrated to insert fully into hairless rat skin in vivo. Microneedles increased skin permeability to insulin, which rapidly and steadily reduced blood glucose levels to an extent similar to 0.05-0.5 U insulin injected subcutaneously. Plasma insulin concentrations were directly measured to be 0.5-7.4 ng/ml. Higher donor solution insulin concentration, shorter insertion time, and fewer repeated insertions resulted in larger drops in blood glucose level and larger plasma insulin concentrations. CONCLUSIONS: Solid metal microneedles are capable of increasing transdermal insulin delivery and lowering blood glucose levels by as much as 80% in diabetic hairless rats in vivo.
PMID: 15212158 [PubMed - indexed for MEDLINE]