Development of matrix based transdermal delivery system for ketotifen

Mechanistic Insights of the Critical Role of Hydrogen Donor in Controlling Drug Release From Acrylate Adhesive

In the present study, a pyrrolidone adhesive and an amide adhesive were synthesized, and their molecular mechanisms of controlled drug release were described. Using zolmitriptan as model drug, in vitro drug release and skin permeation experiments were performed. Adhesive properties were evaluated using modulated differential scanning calorimetry and rheology study. Free volume of polymer was directly obtained by positron annihilation lifetime spectroscopy. Intermolecular interactions between drugs and adhesives were determined by FTIR spectroscopic analysis and molecular simulation. Release percent (24 h) of zolmitriptan from pyrrolidone adhesive was about 55.8 ± 3.1% (w/w), while from amide adhesive, the release percent (24 h) was about 40.1 ± 1.6% (w/w). The free volume sizes of pyrrolidone adhesive and amide adhesive were about 2309.6 ų and 2854.5 ų, respectively, which were much larger than molecular volume of zolmitriptan (about 285.7 ų). Thus, the polymer networks might not hinder drug diffusion from the view of free volume. Comparing chemical structures of pyrrolidone group and primary amide group, the main difference was that primary amide group of amide adhesive possessed 2 hydrogen donors. It was proved that hydrogen bonding between zolmitriptan and hydrogen donor of primary amide group played a critical role in controlling drug release.

(-)-Epigallocatechin gallate (EGCG)-nanoethosomes as a transdermal delivery system for docetaxel to treat implanted human melanoma cell tumors in mice

(-)-Epigallocatechin-3-O-gallate (EGCG), a versatile natural product in fresh tea leaves and green tea, has been investigated as a preventative treatment for cancers and cardiovascular disease. The objective of this study was to develop EGCG-nanoethosomes for transdermal delivery and to evaluate them for treating subcutaneously implanted human melanoma cell tumors. EGCG-nanoethosomes, composed of 0.2% EGCG, 2% soybean phosphatidylcholine, 30% ethanol, 1% Tween-80 and 0.1% sugar esters, were prepared and characterized using laser transmission electron microscopy. These nanoethosomes were smoother and more compact than basic-nanoethosomes with the same components except for EGCG. The effectiveness of transdermal delivery by EGCG-nanoethosomes was demonstrated in an in vitro permeability assay system using mouse skin. The inhibitory effect of docetaxel (DT) loaded in EGCG-nanoethosomes (DT-EGCG-nanoethosomes) was analyzed by monitoring growth of a subcutaneously implanted tumor from A-375 human melanoma cells in mice. Mice treated with DT-EGCG-nanoethosomes exhibited a significant therapeutic effect, with tumors shrinking, on average, by 31.5% of initial volumes after 14 d treatment. This indicated a potential for treating skin cancer. In a pharmacokinetic study, transdermal delivery by DT-EGCG-nanoethosomes enabled sufficient DT exposure to the tumor. Together, these findings indicated that EGCG-nanoethosomes have great potential as drug carriers for transdermal delivery.

Recent developments in silicones for topical and transdermal drug delivery

Silicones have been used in medicines, cosmetics and medical devices for over 60 years. Polydimethylsiloxanes are polymers that are typically used either as an active in oral drug products or as excipients in topical and transdermal drug products. Inherent characteristics like hydrophobicity, adhesion and aesthetics allow silicones to offer function and performance to drug products. Recent technologies like swollen crosslinked silicone elastomer blend networks, sugar siloxanes, amphiphilic resin linear polymers and silicone hybrid pressure sensitive adhesives promise potential performance advantages and improved drug delivery efficacy. This article presents a review of recent silicone material developments focusing on their function as excipients influencing drug delivery in topical and transdermal systems.