Aqueous Solutions Of Sodium Lauryl Sulfate Research Articles

Effect of Sodium Lauryl Sulfate (SLS) Applied as a Patch on Human Skin Physiology and Its Microbiota

In this study, we assessed the change in skin microbiota composition, relative abundance, and diversity with skin physiology disruption induced by SLS patch. Healthy women declaring to have a reactive skin were submitted to a 0.5% aqueous sodium lauryl sulfate solution application under occlusive patch condition for 24 h. Skin properties were characterized by tewametry, corneometry, and colorimetry and bacterial diversity was assessed by 16S rRNA sequencing. Analysis before and one day after SLS patch removal revealed an increase of skin redness and a decrease of stratum corneum hydration and skin barrier function. The relative abundance of taxa containing potential pathogens increase (Firmicutes: Staphylococcaceae; Proteobacteria: Enterobacteriaceae, Pantoea) while some of the most occurring Actinobacteria with valuable skin protection and repair capacities decreased (Micrococcus, Kocuria, and Corynebacterium). We observed an impaired skin barrier function and dehydration induced by SLS patch disturb the subtle balance of skin microbiota towards skin bacterial community dysbiosis. This study provides new insights on the skin bacterial composition and skin physiology simultaneously impaired by a SLS patch.

Solubilization of drugs using sodium lauryl sulfate: Experimental data and modeling

Micellar solubilization is a great method for increasing drugs solubility in aqueous environments. At concentrations above the critical micelle concentration (CMC), micelles are formed and they are able to increase the apparent aqueous solubility of poorly soluble drugs. Sodium lauryl sulfate (SLS) is one of the common solubilizing agents in pharmaceutical sciences. Investigation on the water solubility of drugs in the presence of surfactants and the development of a relationship between drug solubility in the presence of SLS and structural descriptors is an important issue in the prediction and understanding of the solubilization mechanism. The aims of this study are: determination of experimental solubility of drugs in the presence of SLS and development of models for finding a relationship between solubilization factor by SLS and structural descriptors. Samples were prepared by adding excess amount of 19 drugs (with diverse structural and physicochemical properties) to water and an aqueous solution of SLS at different concentrations, that is, less than (0.1%) and above the CMC (0.5%). The mixtures were placed in a shaker-incubator for 72–96 h at 37 °C. Then, the equilibrated samples were filtered and analyzed at maximum wavelengths by UV-spectrophotometry and the concentrations were calculated based on the calibration curves. Afterward, the molecular descriptors of drugs were computed and their relationship with solubilization factor in the presence of SLS was investigated. Most of the drugs showed a considerable increase in solubility above the CMC (0.5%) of SLS. Therefore, the effective mechanism for solubilization by surfactants is the formation of micelles. On the other hand, a good correlation was observed between structural descriptors and solubilization power in the presence of surfactant. Overall, SLS is a good solubilization agent and the solubility in aqueous solution of SLS depends on various structural descriptors.

Ethnic differences in objective and subjective skin irritation response: an international study

Due to global marketing in the cosmetics industry, it is important to assess ethnic population susceptibility when evaluating the safety of cosmetic products or chemicals. To investigate ethnic variations in skin irritation response to positive irritants. Clinical testing was performed in four countries on two ethnic groups - Asian and Caucasian. We performed patch tests on the subjects' back with 0.5% aqueous sodium lauryl sulfate (SLS) and 0.15% retinol prepared in 1,3-butylene glycol. Stinging tests were performed using 5% aqueous lactic acid and 0.001% (w/v) capsaicin prepared in 10% ethanol solution separately. The incidence of self-perceived skin sensitivity was similar in the two ethnic groups. However, the incidence of adverse skin reaction to cosmetics appeared significantly higher in Asian (33.0%) than in Caucasian subjects (11.3%). For standard positive irritants such as 0.5% aqueous SLS solution, Asian subjects showed significantly higher scores than Caucasian subjects. The incidence of positive reaction to the 0.15% retinol patch test tended to be higher in Asian than in Caucasian subjects. Our data also showed that neurosensitivity to 5% lactic acid and 0.001% capsaicin was higher in Asian than in Caucasian subjects. Although self-reported skin sensitivity does not appear to differ according to ethnicity, there are ethnic differences in objective and subjective skin irritation responses to several standard positive materials.

Development and Validation of a Discriminative Dissolution Test for Nimesulide Suspensions

The dissolution test for oral dosage forms has recently widened to a variety of special dosage forms such as suspensions. For class II drugs, such as nimesulide (NMS), this study is very important because formulation problems may compromise drug bioavailability. In the present work, tests with four brands of commercially available NMS (RA, TS, TB, and TC) have been performed in order to study their dissolution at different conditions. The suspensions have been characterized relatively to particle size, pH, and density besides NMS assay and the amount of drug in solution in the suspension vehicles. The dissolution study was conducted using the following media: simulated intestinal fluid, pH 6.8, containing polysorbate 80 (P80) or sodium lauryl sulfate (SLS); phosphate buffer, pH 7.4, with P80 and aqueous solution of SLS. Concerning the quantitative analysis, the UV-VIS spectrophotometry could have been used in substitution to high-performance liquid chromatography since the methodology had been adequately validated. The influence of the drug particle size distribution was significant on the dissolution profiles of NMS formulations, confirming to be a factor that should be strictly controlled in the development of oral suspensions.

Studies on formulation andin vitrodissolution of Embelin tablets

The objective of the present study was to develop a tablet formulation of embelin employing the wet granulation and direct compression techniques. This study was also carried out to design a suitable dissolution medium for embelin. Effect of different diluents like lactose, microcrystalline cellulose, and co-crystallized lactose-microcrystalline cellulose were studied for improving the flow and compressibility. Binders such as starch paste and alcoholic polyvinyl pyrrolidone were used to optimize the crushing strength of the formulation. Dried starch powder was used as a disintegrating agent in both techniques. Pre and post formulation parameters were studied for all the batches. Co-crystallized lactose-microcrystalline cellulose and alcoholic polyvinyl pyrrolidone proved to be the best diluent and binder respectively. Solubility study of embelin in different media revealed that embelin has optimum solubility in phosphate buffer of pH 8 and in 2% aqueous sodium lauryl sulfate solution. Incorporation of 10% v/v ethanol in phosphate buffer of pH 7.4, significantly increased the solubility of embelin. These solutions were also found to be the most suitable media for dissolution of embelin in dissolution studies.

Quantification of Sodium Lauryl Sulfate Penetration into the Skin and Underlying Tissues after Topical Application—Pharmacological and Toxicological Implications

Sodium lauryl sulfate (SLS) is known to penetrate skin and cause cutaneous irritation. Some of these effects have been well‐defined using bioengineering techniques. In this study, the ability of SLS to penetrate skin was quantified in a hairless rat model. In addition, local deep tissue penetration and systemic exposure to SLS were also evaluated to assess the toxic potential of topically applied SLS. SLS was observed to penetrate directly to a depth of about 5–6 mm below the applied site. Systemic redistribution was predominantly responsible in determining concentrations of SLS in tissues deeper than 5–6 mm. Epidermal concentrations of SLS after application of 1% (34 mM) aqueous SLS solution for 24 h were above the threshold levels which are known to evoke typical skin irritation responses. Deeper underlying tissues including dermis, subcutaneous, and muscle may also be exposed to high levels of SLS. Topically applied SLS was also observed in blood and contralateral tissues but the observed levels were not likely to elicit any systemic side effects at these doses. Traces of SLS were observed in tissues 7 days after single 24 h application of SLS, which supports the prolonged barrier disruption data generated using conventional bioengineering techniques. Cumulative treatment of SLS significantly increased the concentration of this compound in the underlying epidermis. The known preferential affinity of SLS for skin lipids and proteins was further confirmed by both in vitro and in vivo results. However, in vitro studies failed to predict the underlying tissue toxicity of SLS under the patch site when compared to the in vivo results. Such quantitative pharmacokinetic–pharmacodynamic correlations may be useful predictors for effective use of surfactants as penetration enhancers in cosmetic, pharmaceutical, and industrial applications.

Coalescence behavior of two bubbles growing side-by-side

Coalescence percentage and coalescence times of thin films formed between nitrogen bubbles wee measured in dilute aqueous solutions of sodium laurylsulfate, n-amyl alcohol, and l-butanol. The bubble pairs were formed on two adjacent capillary tubes through a well-controlled stepping motor, and the coalescence time was determined by an optical sensing method. The results showed the appearance of a sharp transition concentration, at which the coalescence percentage was drastically reduced. But the effect of bubbling frequency on transition concentration showed the opposite tendency in some cases, according to the properties of the solute added. Coalescence times increased with solute concentration and also increased with surface tension gradient.

Sodium lauryl sulfate irritant patch tests. III. Evaporation of aqueous vehicle influences inflammatory response

Patch tests with aqueous solutions of the irritating detergent sodium lauryl sulfate (SLS) elicit varying degrees of inflammation from subject to subject and from site to site. For an investigation of the causes of this variability, two patch tests with 10% aqueous solutions of SLS were applied to adjacent areas of ventral forearm skin of eighteen volunteers. In one test the water vehicle was allowed to evaporate from the patch test unit before the patches were applied. After 22 hours the patch tests were removed, and 2 hours later the degree of inflammation was graded. Less inflammation was present at the site of the dry patch test in fifteen of eighteen subjects, and the score of inflammation between each pair was significantly less at the dry patch test site (p less than 0.001). These studies show that evaporation of water from aqueous solutions can influence the irritating potential of SLS on human skin.

Interaction between styrene–ethylene oxide block copolymers and sodium lauryl sulfate in aqueous solution

AbstractInteractions of water‐soluble AB block copolymers of polystyrene and poly(ethylene oxide) with sodium lauryl sulfate (SLS) in aqueous solution were investigated by high‐resolution proton magnetic resonance (NMR). The viscosity in aqueous SLS solution was also measured. From the NMR results in D2O, it appears that molecular motions of the polystyrene blocks of the copolymer in aqueous solution are activated by interaction between the polystyrene blocks and the added SLS. From solution viscosity, on the other hand, it is apparent that a complex is formed between the copolymer and SLS and that it exhibits typical polyelectrolyte properties. The polyelectrolyte character is attributable largely to intrachain repulsions between like charges of the SLS anions adsorbed on the poly(ethylene oxide) blocks of the copolymers since the polystyrene blocks are insoluble in water and the styrene content is less than 10%.

Tracer studies of radioactive sodium estrone sulfate (S35) in cases of advanced breast cancer.

Tracer studies of radioactive sodium estrone sulfate (S35) in cases of advanced breast cancer.