Polymers and Graphene-Based Materials as Barrier Coatings

Currently, a wide range of materials are being used as barrier coatings for different applications. Among them, polymers and graphene have been the focus of many studies. Polymers are used in numerous industries due to their remarkable properties, including resistance to thermal degradation, resistance to chemical permeation, and good mechanical properties. On the other hand, graphene, a one-atom-thick and two-dimensional material, does not allow the permeation of gases or liquid molecules through its plane; thus, it has been considered one of the promising nanomaterials used in gas and liquid barrier applications and corrosion inhibition coatings.

A Review on Chemical Permeation Enhancers used in the Formulation of Transdermal Drug Delivery System

Skin penetration enhancement technology is a rapidly evolving area that will greatly increase the quantity of transdermal drug delivery medications. Penetration enhancers are used to facilitate the movement of drugs through the skin barrier. Numerous methods exist for extending partition enhancement. The enhancers' contact with the polar head of the lipid groups is the potential means for increasing the penetration. Penetration enhancers improve the amount of free water molecules between the bilayer, leading to an improvement of the polar drug diffusion cross section. This article focuses on the different compounds assessed for improving penetration activity like sulphoxides, azones, pyrrolidones, alcohols and alkanols, glycols, surfactants and terpenes.

Improvement of Resveratrol Permeation through Sublingual Mucosa: Chemical Permeation Enhancers versus Spray Drying Technique to Obtain Fast-Disintegrating Sublingual Mini-Tablets

Resveratrol (RSV) is a natural polyphenol with several interesting broad-spectrum pharmacological properties. However, it is characterized by poor oral bioavailability, extensive first-pass effect metabolism and low stability. Indeed, RSV could benefit from the advantage of the sublingual route of administration. In this view, RSV attitudes to crossing the porcine sublingual mucosa were evaluated and promoted both by six different chemical permeation enhancers (CPEs) as well as by preparing four innovative fast-disintegrating sublingual mini-tablets by spray drying followed by direct compression. Since RSV by itself exhibits a low permeation aptitude, this could be significantly enhanced by the use of CPEs as well as by embedding RSV in a spray-dried powder to be compressed in order to prepare fast-disintegrating mini-tablets. The most promising observed CPEs (menthol, lysine and urea) were then inserted into the most promising spray-dried excipients’ compositions (RSV-B and RSV-C), thus preparing CPE-loaded mini-tablets. However, this procedure leads to unsatisfactory results which preclude the possibility of merging the two proposed approaches. Finally, the best spray-dried composition (RSV-B) was further evaluated by SEM, FTIR, XRD and disintegration as well as dissolution behavior to prove its effectiveness as a sublingual fast-disintegrating formulation.

Skin Permeation of Nanoparticles: Mechanisms Involved and Critical Factors Governing Topical Drug Delivery

Transdermal route has been an ever sought-after means of drug administration, regarded as being the most convenient and patient compliant. However, skin poses a great barrier to the entry of the external particles including bacteria, viruses, allergens, and drugs as well (mostly hydrophilic or high molecular weight drugs), consequent to its complex structure and composition. Among the various means of enhancing drug permeation through the skin, e.g. chemical permeation enhancers, electroporation, thermophoresis, etc. drug delivery through nanoparticles has been of great interest. Current literature reports a vast number of nanoparticles that have been implicated for drug delivery through the skin. However, a precise account of critical factors involved in drug delivery and mechanisms concerning the permeation of nanoparticles through the skin is necessary. The purpose of this review is to enumerate the factors crucial in governing the prospect of drug delivery through skin and classify the skin permeation mechanisms of nanoparticles. Among the various mechanisms discussed are the ones governed by principles of kinetics, osmotic gradient, adhesion, hydration, diffusion, occlusion, electrostatic interaction, thermodynamics, etc. Among the most common factors affecting skin permeation of nanoparticles that are discussed include size, shape, surface charge density, composition of nanoparticles, mechanical stress, pH, etc.

Exposure of Agriculture Workers to Pesticides: The Effect of Heat on Protective Glove Performance and Skin Exposure to Dichlorvos

Dichlorvos is a toxic organophosphate insecticide that is used in agriculture and other insecticide applications. Dermal uptake is a known exposure route for dichlorvos and chemical protective gloves are commonly utilized. Chemical handling and application may occur in a variety of thermal environments, and the rates of both chemical permeation through gloves and transdermal penetration may vary significantly with temperature. There has been no published research on the temperature-dependent kinetics of these processes for dichlorvos and thus, this study reports on the effects of hot conditions for the concentrated and application strength chemical. Dichlorvos breakthrough times for non-disposable polyvinyl chloride (PVC) gloves at 60 °C were approximately halved compared to 25 °C for the concentrate (2 vs. 4 h) and more than halved at application strength (3 vs. >8 h). From permeation experiments covering 15–60 °C, there was a 460-fold increase in cumulative permeation over 8 h for the concentrated dichlorvos and the estimated activation energy halved. Elevated temperature was also shown to be a significant factor for human skin penetration increasing the cumulative penetration of concentrate dichlorvos from 179 ± 37 to 1315 ± 362 µg/cm2 (p = 0.0032) and application strength from 29.8 ± 5.7 to 115 ± 19 µg/cm2 (p = 0.0131). This work illustrates the important role temperature plays in glove performance and health risk via dermal exposure. As such, it is important to consider in-use conditions of temperature when implementing chemical hygiene programs.