Topical emollients are known to provide symptomatic relief for atopic dermatitis. In hospitals, wet-wrap therapy has been shown to benefit children with moderate-to-severe atopic dermatitis (AD), but the application of wet-wraps is tedious and time-consuming. Topical emollients have low residence time and often dry out easily. The aim of this work was to develop a hydrogel-gauze dressing that is not only easy to apply but also rehydrates and traps moisture to provide longer relief for AD patients. In this study, a prototype hydrogel-gauze dressing was developed with varying ratios of sodium carboxymethylcellulose (NaCMC) and propylene glycol. The hydrogel-gauze dressings were assessed based on the moisture vapor transmission rate, moisture absorption, mechanical properties and storage stability over three months. Then, the efficacy of the hydrogel-gauze dressing was compared to topical emollients using transgenic NC/Nga mice with AD-like lesions. The NaCMC hydrogel-gauze dressings significantly lowered transepidermal water loss, and the animals displayed a faster recovery, which indicates that hydrogel-gauze dressings can trap moisture more effectively and accelerate AD healing. Hence, we propose that hydrogel-gauze dressings can potentially become an alternative to wet-wrap therapy due to the ease of application and the higher efficacy compared to topical products.
Virgin coconut oil (VCO)-in-water, nano-emulsion in the form of cream stabilized by Emulium Kappa as an emulsifier, was prepared by using the Emulsion Inversion Point method. A nano-emulsion with droplet size <300 nm was then obtained. VCO has recently become a more popular new material in the cosmetic industries. Emulium Kappa is an ionic emulsifier that contains sodium stearoyl lactylate, the active whitening ingredient was Kojic Dipalmitate. Ostwald ripening is the main destabilizing factor for the nano-emulsion. This decline can be reduced by adding non-soluble oil, namely squalene, to the virgin coconut oil. We tested VCO:squalene in the ratios of 10:0, 9.8:0.2, 9.6:0.4, 9.4:0.6, 9.2:0.8, 9:1 and 8:2 and discovered that squalene's higher molecular weight (above critical molecular weight) resulted in low polarity and insolubility in the continuous phase. The continuous partitioning between the droplets results in the decline of Ostwald ripening. Furthermore, flocculation may occur due to the instability of nano-emulsion, especially for the preparations with little or no squalene at all. The stability of the nano-emulsion was evaluated by the electrophoretic properties of the emulsion droplets. The zeta potential values for the emulsion increased as the percentage of squalene oil increased.
Drug permeation through the intercellular lipids, which pack around and between corneocytes, may be enhanced by increasing the thermodynamic activity of the active in a formulation. However, this may also result in unwanted drug crystallisation on and in the skin. In this work, we explore the combination of ATR-FTIR spectroscopy and multivariate data analysis to study drug crystallisation in the skin. Ex vivo permeation studies of saturated solutions of diclofenac sodium (DF Na) in two vehicles, propylene glycol (PG) and dimethyl sulphoxide (DMSO), were carried out in porcine ear skin. Tape stripping and ATR-FTIR spectroscopy were conducted simultaneously to collect spectral data as a function of skin depth. Multivariate data analysis was applied to visualise and categorise the spectral data in the region of interest (1700-1500cm(-1)) containing the carboxylate (COO(-)) asymmetric stretching vibrations of DF Na. Spectral data showed the redshifts of the COO(-) asymmetric stretching vibrations for DF Na in the solution compared with solid drug. Similar shifts were evident following application of saturated solutions of DF Na to porcine skin samples. Multivariate data analysis categorised the spectral data based on the spectral differences and drug crystallisation was found to be confined to the upper layers of the skin. This proof-of-concept study highlights the utility of ATR-FTIR spectroscopy in combination with multivariate data analysis as a simple and rapid approach in the investigation of drug deposition in the skin. The approach described here will be extended to the study of other actives for topical application to the skin.