Magnetophoresis is a method of enhancement of drug permeation across the biological barriers by application of magnetic field. The present study investigated the mechanistic aspects of magnetophoretic transdermal drug delivery and also assessed the feasibility of designing a magnetophoretic transdermal patch system for the delivery of lidocaine. In vitro drug permeation studies were carried out across the porcine epidermis at different magnetic field strengths. The magnetophoretic drug permeation “flux enhancement factor” was found to increase with the applied magnetic field strength. The mechanistic studies revealed that the magnetic field applied in this study did not modulate permeability of the stratum corneum barrier. The predominant mechanism responsible for magnetically mediated drug permeation enhancement was found to be “magnetokinesis”. The octanol/water partition coefficient of drugs was also found to increase when exposed to the magnetic field. A reservoir type transdermal patch system with a magnetic backing was designed for in vivo studies. The dermal bioavailability (AUC0–6 h) from the magnetophoretic patch system in vivo, in rats was significantly higher than the similarly designed nonmagnetic control patch.

No abstract

No abstract

No abstract

X-ray fluorescence is subject to significant matrix effects, which must be corrected in order to obtain accurate quantitative results. These are due to both absorption and enhancement effects, which are a consequence of the fact that both the analyte and the matrix absorb and fluoresce in the X-ray region, and this affects the magnitude of the analyte signal. Instruments, especially hand-held energy-dispersive X-ray analyzers designed for use by nontechnical personnel, typically come with software that use general algorithms that apply the appropriate matrix effect corrections without user involvement. Though user-friendly, this approach obscures the steps needed to obtain accurate quantitative results. In this laboratory exercise students obtain X-ray fluorescence data for both elements in binary mixtures of metal powders. The matrix effect is corrected using the analyte and matrix measurement data and a simple influence factor model. The exercise gives students a better sense of matrix effects and illustrates one approach to correcting for them.