Desalination using modified configuration of supported liquid membrane with enhancement of mass transfer of NaCl

Supported liquid membranes (SLM) suffer from very slow mass transfer of the solute from the donor phase (DP) to the receptor phase (RP) through the liquid membrane (LM). In the present work, an attempt was made to accelerate the mass transfer in SLM by creating a modified configuration in which the DP and RP are made to flow either co- or counter-currently to each other. Variables, which could affect the removal of NaCl, were the volume ratio of DP to RP, type and quantity of sequestering agent (SA), presence of mobile carrier (MC), type of LM, and flow rate of DP and RP. The results showed that the higher the flow rate of DP and RP, the higher the mass transfer of NaCl. Quantity and type of SA and type of LM were prime important factors. Remarkably, the time required for transfer of NaCl from DP to RP was reduced from several hours in the case of stagnant SLM to several minutes in the present work. The mass transfer of NaCl was analysed based on kinetic laws of two consecutive irreversible first-order reactions. The values achieved establish the process is diffusion controlled, and the membrane entrance rate constants increase directly with initial concentration (Ci) and inversely with quantity of SA.

Iono-molecular Separation with Composite Membranes VI. Nitro-phenol separation through sulfonated polyether ether ketone on capillary polypropylene membranes

The importance of removing and / or separating nitro phenols from aqueous solutions through membranes is substantiated by the multitude of recent research in the field, which broadly justifies both the economic and ecological reasons of such an approach. The present paper outlines the results of the transfer of nitro phenols through a membrane system made up of PPET impregnated polypropylene capillaries (PP) impregnated with sulfonate polyetheretherketone (SPEEK). The experiments were carried out in a PP-SPEEK capillary membrane module, with a useful size of 1 m2. Determinations made by using a 4 L / min flow rate source at a 5 mg / l nitrophenol concentration and pH 5 or pH 7, and the pH 12 receiving phase and a flow rate of 0.3 L / min, revealed that o- and p-nitrophenol were transferred much faster than m-nitrophenol (the flux is nearly double); the source phase of the system is concentrated in m-nitrophenol, and the receptor phase in o- and p-nitro phenols; the transfer data correlates with the higher water solubility of m-nitrophenol; mono nitro phenols transfer much faster than di nitrophenol, but both the mono and di nitrophenol streams decrease over time; after 4-5 hours of work, the mono nitrophenol concentration triples in the receiving phase, while the 2,4-dinitrophenol concentration doubles in the source phase.

The Low Keratin Affinity of Efinaconazole Contributes to Its Nail Penetration and Fungicidal Activity in Topical Onychomycosis Treatment

ABSTRACTOnychomycosis is a common fungal nail disease that is difficult to treat topically due to the deep location of the infection under the densely keratinized nail plate. Keratin affinity of topical drugs is an important physicochemical property impacting therapeutic efficacy. To be effective, topical drugs must penetrate the nail bed and retain their antifungal activity within the nail matrix, both of which are adversely affected by keratin binding. We investigated these properties for efinaconazole, a new topical antifungal for onychomycosis, compared with those of the existing topical drugs ciclopirox and amorolfine. The efinaconazole free-drug concentration in keratin suspensions was 14.3%, significantly higher than the concentrations of ciclopirox and amorolfine, which were 0.7% and 1.9%, respectively (P< 0.001). Efinaconazole was released from keratin at a higher proportion than in the reference drugs, with about half of the remaining keratin-bound efinaconazole removed after washing. In single-dosein vitrostudies, efinaconazole penetrated full-thickness human nails into the receptor phase and also inhibited the growth ofTrichophyton rubrumunder the nail. In the presence of keratin, efinaconazole exhibited fungicidal activity againstTrichophyton mentagrophytescomparable to that of amorolfine and superior to that of ciclopirox. In a guinea pig onychomycosis model withT. mentagrophytesinfection, an efinaconazole solution significantly decreased nail fungal burden compared to that of ciclopirox and amorolfine lacquers (P< 0.01). These results suggest that the high nail permeability of efinaconazole and its potent fungicidal activity in the presence of keratin are related to its low keratin affinity, which may contribute to its efficacy in onychomycosis.

Fluorometric quantification of protoporphyrin IX in biological skin samples from in vitro penetration/permeation studies

A fluorometric analytical method was developed for quantification of protoporphyrin IX (PpIX) in skin samples and receptor phase solution after in vitro cutaneous penetration/permeation studies. Analytical conditions used were: excitation and emission wavelengths: 400 nm and 632 nm; bandwidth: 0.5 nm; excitation and emission slits: 10/10. PpIX was recovered from two different layers of skin, the stratum corneum (SC) and the epidermis plus dermis ([E+D]), by vortex homogenization, probe and bath sonication, using DMSO as an extraction solvent. The detection and quantification limits were 0.002 and 0.005 μg/mL, respectively. The assay was linear from 0.005 - 0.5 μg/mL. The within-day and between-day assay precision and accuracy in DMSO and receptor phase solution were each studied at the two concentration levels 0.04 and 0.2 μg/mL, and 0.01 and 0.08 μg/mL, respectively. The coefficients of variation and deviation from the theoretical values were lower than 5%. The skin recovery of PpIX from SC and [E+D] layers using two different concentrations (0.5 and 1.0 μg/mL) were all above 90.0%. The method described has potential application to in vitro penetration/permeation studies of PpIX using porcine skin as a biological membrane model.

Assessment of in vitro methodologies to determine topical and transdermal delivery of the flavonoid quercetin

To be effective against the oxidative damages induced by UVB irradiation in the skin, the drug needs to release from the formulation in which it was incorporated and reach the skin layers where the ROS are generated. Thus, it is very important the development of a robust and sensitive methodology to extract and quantify in different skin layers the antioxidant agent delivered from topical formulations. Therefore, in the present work suitable methods to extract and quantify quercetin in skin samples and receptor phase after in vitro penetration studies were developed. The results demonstrated that the recovery from two different layers of skin, the SC and [E+D], using two different methods of quantification (DPPH• assay and HPLC, respectively), was 93.8 % when the quercetin spiked dose was 50 µg/mL, 100.4 % when it was 100 µg/mL and 89.9 % for 250 µg/mL and the average recovery of the quercetin extraction from receptor phase when dichloromethane was used as extractor solvent was 96%. These results demonstrate that the described methods have a potential application to in vitro skin penetration studies of quercetin, since it showed to be accurate and sensitive.