Context: In this study an investigation of cationic surfactants-modified natural zeolites as drug formulation excipient was performed. Objective: The aim of this work was to carry out a study of the purified natural zeolitic tuff with high amount of clinoptilolite as a potential carrier for molecules of pharmaceutical interest. Materials and methods: Two cationic surfactants (benzalkonium chloride and hexadecyltrimethylammonium bromide) were used for modification of the zeolitic surface in two levels (equal to and twice as external cation-exchange capacity of the zeolitic tuff). Prepared samples were characterized by Fourier transform infrared spectroscopy, thermogravimetric, high-performance liquid chromatography analysis, and powder flow determination. Different surfactant/zeolite composites were used for additional investigation of three model drugs: diclofenac diethylamine, diclofenac sodium, and ibuprofen by means of adsorption isotherm measurements in aqueous solutions. Results: The modified zeolites with two levels of surfactant coverage within the short activation time were prepared. Determination of flow properties showed that modification of zeolitic surface reflected on powder flow characteristics. Investigation of the model drugs adsorption on the obtained composites revealed that a variation between adsorption levels was influenced by the surfactant type and the amount present at the surface of the composites. Discussion and conclusion: In vitro release profiles of the drugs from the zeolite-surfactant-drug composites revealed that sustained drug release could be attained over a period of 8 hours. The presented results for drug uptake by surfactant-zeolite composites and the afterward drug release demonstrated the potential use of investigated modified natural zeolite as excipients for advanced excipients in drug formulations.

Stem cells are undifferentiated cells present in numerous tissues. Homeostasis and regeneration of those tissues depend on stem cell activity. Skin is the biggest organ of human body that is undergoing constant cellular turnover enabled by the activity of its own stem cells. In epidermis they are located in the bulge region of hair follicle, sebaceous glands and interfollicular epidermis. They also appear in dermis. Their activity is regulated by intrinsic programmes, niche stimuli and environmental factors. Aging of skin stem cells is associated with loss of proper signalling and accumulation of stress induced changes in cells. Cosmetic active ingredients claiming to protect skin stem cells have following effects: to neutralise negative effects of UV rays, to neutralise free radicals, to provide optimal conditions for skin and hair renewal. Plant stem cell extracts are innovative approach for obtaining natural active ingredients in controlled conditions, in ecological and sustainable manner, with possibility of inducing synthesis of desired secondary metabolites. Differences that exist between human and plant stem cells, and their regulatory substances, are defining their application in cosmetics. Their effects on skin are antioxidant, soothing, protection of skin stem cells and skin cells from UV ray induced damages or stimulation of synthesis of extracellular proteins.