Jeffrey Edwards's scientific contributions

The aim of the study was determine the effect of magnetic film array technology on the skin permeation of urea. A 5% urea gel was applied to human epidermal membrane in vitro and human skin in vivo. Application of gel with magnetic film array and plastic occlusive film was compared with application of gel with a plastic occlusive film and non-magnetic film. In-vitro epidermal penetration was determined using a Franz-type diffusion system. In-vivo permeation and changes in epidermal properties were visualised by optical coherence tomography. The mean cumulative permeation of urea over 2 h for magnetic film array application was 89.54 +/- 7.34 microg/cm(2) as compared with 20.83 +/- 2.02 microg/cm(2) for passive occluded application (mean +/- SEM, n = 9/8), representing greater than 4-fold increase over the 2-h application time period. Administration of urea with the magnetic film array resulted in the lag time being reduced from 40.58 +/- 3.98 to 21.13 +/- 6.27 min (P < 0.02), while steady state flux increased from 0.24 +/- 0.03 to 0.75 +/- 0.06 microg/cm(2) per min (P < 0.0001). Under active occlusion, the relative change in epidermal thickness as determined by optical coherence tomography increased by 16 and 11% at 30 and 60 min, respectively. Administration with a novel magnetic film array technology provided enhanced skin penetration of urea and increased epidermal hydration when compared with administration under an occlusive film only.

The aim of the present study was to evaluate the skin permeation of naltrexone (NTX) under the influence of a pulsed electromagnetic field (PEMF). The permeation of NTX across human epidermis and a silicone membrane in vitro was monitored during and after application of the PEMF and compared to passive application. Enhancement ratios of NTX human epidermis permeation by PEMF over passive diffusion, calculated based on the AUC of cumulative NTX permeation to the receptor compartment verses time for 0-4 h, 4-8 h, and over the entire experiment (0-8 h) were 6.52, 5.25, and 5.66, respectively. Observation of the curve indicated an initial enhancement of NTX permeation compared to passive delivery whilst the PEMF was active (0-4 h). This was followed by a secondary phase after termination of PEMF energy (4-8 h) in which there was a steady increase in NTX permeation. No significant enhancement of NTX penetration across silicone membrane occurred with PEMF application in comparison to passively applied NTX. In a preliminary experiment PEMF enhanced the penetration of 10 nm gold nanoparticles through the stratum corneum as visualized by multiphoton microscopy. This suggests that the channels through which the nanoparticles move must be larger than the 10 nm diameter of these rigid particles.

Poor skin permeability and stability limits the application of peptides to the skin. Enhanced skin permeation could offer new therapies for a range of dermatological and cosmetic applications. The aim of this study was to investigate the application of a novel magnetic field enhancement technology to peptide delivery across the skin. Ala‐Trp was used as a model dipeptide. Stability of the dipeptide in a range of conditions and with exposure to skin was determined. Dermaportation‐magnetic field technology increased the in vitro permeability coefficient of Ala‐Trp across human epidermis from 7.7 × 10 ⁻⁴ cm/h with passive diffusion to 1.94 × 10 ⁻² cm/h with Dermaportation. Ala‐Trp was unstable with exposure to human epidermis. Following permeation across the epidermis, a degradation product was detected in the receptor solution with the amount increasing up to 6 h. Given the susceptibility of peptides to degradation in the skin it is essential that they are delivered rapidly across the skin in order to maximize the opportunity for delivery of the native peptide. Dermaportation offers a potential new delivery method for skin delivery of peptides for a range of dermatological and cosmetic applications. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 655–662, 2008. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

The purpose of the present study was to develop a reverse-phase high performance liquid chromatographic (HPLC) assay for quantifying 5-aminolevulinic acid (ALA). The assay was applied to study the skin permeation of ALA and the influence of a novel skin penetration enhancement technology. Separation was achieved utilizing a Phenomenex Jupiter C(18) column following fluorescence derivatization with fluorescamine. The assay was linear (r(2)>0.99) with a minimum limit of quantitation of 400 ng/mL. The inter- and intraday variation was 1.6 and 0.9% at the lower end of the linear range and 1.5 and 1.9% at the upper end, respectively. The HPLC assay and fluorescence derivatization procedure is sensitive, simple, rapid, accurate and reproducible and offers advantages with regard to stability of ALA in comparison to other fluorescence derivatization methods. Results from the preliminary skin permeation study demonstrated substantial skin penetration of ALA only when applied with Dermaportation as a skin penetration enhancement device.