Polymer microneedles for controlled-release drug delivery.

Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Pharmaceutical Research (Impact Factor: 4.74). 05/2006; 23(5):1008-19. DOI: 10.1007/s11095-006-0028-9
Source: PubMed

ABSTRACT As an alternative to hypodermic injection or implantation of controlled-release systems, this study designed and evaluated biodegradable polymer microneedles that encapsulate drug for controlled release in skin and are suitable for self-administration by patients.
Arrays of microneedles were fabricated out of poly-lactide-co-glycolide using a mold-based technique to encapsulate model drugs--calcein and bovine serum albumin (BSA)--either as a single encapsulation within the needle matrix or as a double encapsulation, by first encapsulating the drug within carboxymethylcellulose or poly-L: -lactide microparticles and then encapsulating drug-loaded microparticles within needles.
By measuring failure force over a range of conditions, poly-lactide-co-glycolide microneedles were shown to exhibit sufficient mechanical strength to insert into human skin. Microneedles were also shown to encapsulate drug at mass fractions up to 10% and to release encapsulated compounds within human cadaver skin. In vitro release of calcein and BSA from three different encapsulation formulations was measured over time and was shown to be controlled by the encapsulation method to achieve release kinetics ranging from hours to months. Release was modeled using the Higuchi equation with good agreement (r2 > or = 0.90). After microneedle fabrication at elevated temperature, up to 90% of encapsulated BSA remained in its native state, as determined by measuring effects on primary, secondary, and tertiary protein structure.
Biodegradable polymer microneedles can encapsulate drug to provide controlled-release delivery in skin for hours to months.

1 Bookmark
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The topical and transdermal delivery of active cosmetic ingredients requires safe and non-toxic means of reaching the target sites without causing any irritation. Preservation of the active ingredients is also essential during formulation, storage and application of the final product. Since many biologically active substances are not stable and sensitive to temperature, pH, light and oxidation, they require encapsulation to protect against unwanted degradation and also to target specific and controlled release of the active substance. The use of biodegradable polymers as encapsulation materials offers several advantages over other carrier materials. Encapsulation of active ingredients using biodegradable polymeric carriers can facilitate increased efficacy and bioavailability and they are also removed from the body via normal metabolic pathways. This article reviews current research on biodegradable polymers as carrier or encapsulation materials for cosmetic and personal care applications. Some of the challenges and limitations are also discussed. Examples of biodegradable polymers reviewed include polysaccharides, poly α-esters, polyalkylcyanoacrylates and polyamidoamine dendrimers. © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.
    International journal of cosmetic science 10/2012;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The skin serves as a semi-permeable barrier that protects the body from pathogens and water loss. The stratum corneum, the upper 10-15 µm layer of skin, is the primary barrier layer. Due to its structure, only drugs that are lipophilic and with a low molecular weight (<500 Da) can penetrate intact skin. This study examines the use of microdermabrasion as a method of removing the stratum corneum to increase the skin's permeability to hydrophilic molecules, proteins, and vaccines. Microdermabrasion is a FDA-approved cosmetic skin resurfacing procedure that removes the stratum by bombarding it with abrasive particles under vacuum. The aims of this thesis are focused on optimizing the microdermabrasion conditions that will selectively remove stratum corneum, evaluating the transport of different sized molecules through abraded skin in vitro, examining drug efficacy in vivo by delivering insulin to diabetic rats, and examining the rate of skin healing after treatment. Microdermabrasion can be used as a non-invasive transdermal drug technique to safely remove stratum corneum to make the skin more permeable to waters soluble drugs and proteins.
  • [Show abstract] [Hide abstract]
    ABSTRACT: There has been an increasing interest in applying biotechnology in formulating and characterising new and innovative drug delivery methods, e.g., drug-loaded biodegradable microneedles within the area of transdermal delivery technology. Recently, microneedles have been proposed for use in pain management, e.g., post-operative pain management through delivery of a local anaesthetic, namely, lidocaine. Lidocaine is a fairly common, marketed prescription-based, local anaesthetic pharmaceutical, applied for relieving localised pain and lidocaine-loaded microneedles have been explored. The purpose of this review is to evaluate the properties of biodegradable polymers that may allow the preparation of microneedle systems, methods of preparing them and pharmacokinetic conditions in considering the potential use of lidocaine for delivery through the skin.
    Biotechnology Letters 05/2013; · 1.85 Impact Factor


Available from