Content
1.Introduction
Over the last several decades, intense studies about the electrical enhancement of drug delivery across the skin have been done. During this period, tons of experimental data have been collected and the meaningful improvement of a diverse array of molecules has been achieved. One of attractive approaches to achieve the desired systemic or local action of drugs is to deliver therapeutic agents into and/or across skin. Transdermal drug delivery shows many advantages over the conventional routes, including reduced side effects, noninvasiveness, improved patient compliance, bypassing first-pass metabolism and imparting prolonged drug delivery properties. This approach also allows for the almost immediate withdrawal of treatment to avoid acute side effects, if needed. However, the exceptional and unique architecture of the skin makes transport of molecules challenging. The stratum corneum (SC), an outermost layer of the skin, is the main obstacle resisting drug molecule permeate through skin. The SC consists of keratin-filled corneocytes and highly organized lipid bilayers, which block the transport of molecules with small molecular weight.
2.Purpose
This project aims at the investigation over several variables including intensity of current, pH of formulation, ionic strength of buffer and direction of electricity. The final goal of this project is to apply this idea into more drug molecules to predict a more universal dosage form for the delivery of peptides and proteins.
3.Methods
One of methods to improve the absorption is iontophoresis, a technique of non-invasive transdermal drug delivery based on the transfer of charged molecules using a low-intensity electric current. Both local and systemic administration are possible. It is basically an injection without the needle. This non-invasive method is to propelling high concentrations of a charged substance, normally a medication or bioactive agent, transdermally by repulsive electromotive force using a small electrical charge applied to an iontophoretic chamber containing a similarly charged active agent and its vehicle. One or two chambers are filled with a solution containing an active ingredient and its solvent, also called the vehicle. The positively charged chamber, called the anode, will repel a positively charged chemical, whereas the negatively charged chamber, called the cathode, will repel a negatively charged chemical into the skin.
Two kinds of motion for iontophoresis are electrorepulsion and electroosmosis. In this study, we want to investigate which motion can contribute to transport of molecules more. The sample drug we are using is bovine serum albumin. The advantage of this protein over insulin or calcitonin is its comparatively low commercial price. Albumin has a molecular weight roughly 66 KDa with a 4.5 pI. During the initial formulation stage, a 7.4 pH environment is preferred based on its similarity as human body. At each time interval, the receipt chamber was sampled of 0.1 mL or 0.2 mL under different condition such as different voltages, current and pH. The concentrations of albumin were determined by HPLC. The relationship between concentration and factors are obtained through linear or nonlinear curves.
4. References
1) Mark R Prausnitz, Robert Langer; Transdermal drug delivery; Nature Biotechnology; Vol 26, Number 11, November 2008.
