Vliv alkoholu na ionizující a neionizující léčiva uvolňovaná z hydrofilních, lipofilních a duálních matric

The aim of this work was to investigate and quantitatively evaluate the effect of presence of alcohol on in vitro release of ionizing and non-ionizing drug from hydrophilic, lipophilic and hydrophilic-lipophilic matrix tablets. The Food and Drug Administration (FDA) recommends in vitro dissolution testing of extended release formulations in ethanolic media up to 40% because of possible alcohol-induced dose dumping effect. This study is focused on comparison of the dissolution behavior of matrix tablets (based on hypromellose and/or glyceryl behenate as retarding agent) of the same composition containing different type of drug - ionizing tramadol hydrochloride (TH) and non-ionizing pentoxifylline (PTX). The dissolution tests were performed in acidic medium (pH 1.2) and in alcoholic medim (20%, 40% of ethanol) and the changes of tablets were observed also photographically. It was found that the alcohol resistence of the hydrophilic-lipophilic formulations with TH and the hydrophilic-lipophilic formulations with PTX containing a higher amount of hypromellose does not reflect the alcohol resistence of the formulations with pure hypromellose or glyceryl behenate. Both hydrophilic-lipophilic formulation with TH and more lipophilic formulation with PTX show significant alcohol dose dumping effect. (C) 2019 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.Cílem práce bylo studium vlivu přítomnosti alkoholu při uvolňování léčiv z hydrofilních, lipofilních i duálních matric

Nový přístup k managmentu disolučních testů a získání kinetických a termodynamických dat:: Uvolňování modelového léčiva z matricové tablety založené na glyceryl behenátu

This study is focused on the use of glyceryl behenate as a lipophilic excipient of matrix tablets providing controlled drug release. The aim of this study is to evaluate activation energy (EA) and changes of the thermodynamic parameters (Delta H, Delta S, Delta G) of a dissolution process. These values, which have not yet been published, can lead to better understanding of a drug release mechanism and can extend the use options of glyceryl behenate in the pharmaceutical industry. Values of Delta H, Delta S, Delta G and E-A, providing an overall thermodynamic view on the studied matrix tablets, are evaluated based on the temperature-dependences of the release rate constant of a model drug (temperature range 25 - 45 degrees C). The studied lipophilic matrix tablets contain 10% to 50% of glyceryl behenate. Dissolution testing is carried out in an aqueous solution of HCl with addition of NaCl (pH1.2). Positive values of Delta H in the range of 3.83 to 56.13 kJ mol(-1) and positive values of Delta G indicate that the dissolution of the studied glyceryl behenate matrix tablets is an endothermic process which does not proceed spontaneously (in a temperature range of 25 - 45 degrees C). The negative slope of the linear curves of enthalpy-entropy compensation confirms the entropy-driven dissolution.Studie je zaměřena na použití glyceryl behenátu jako lipofilního excipientu matricové tablety s prodlouženým uvolňováním. Cílem studie byl vývoj aktivační energie a změn termodynamických paramaetrů disolučního procesu

Hierarchical TiO₂ Layers Prepared by Plasma Jets

Heterogeneous photocatalysis of TiO2 is one of the most efficient advanced oxidation processes for water and air purification. Here, we prepared hierarchical TiO2 layers (Spikelets) by hollow-cathode discharge sputtering and tested their photocatalytic performance in the abatement of inorganic (NO, NO2) and organic (4-chlorophenol) pollutant dispersed in air and water, respectively. The structural-textural properties of the photocatalysts were determined via variety of physico-chemical techniques (XRD, Raman spectroscopy, SEM, FE-SEM. DF-TEM, EDAX and DC measurements). The photocatalysis was carried out under conditions similar to real environment conditions. Although the abatement of NO and NO2 was comparable with that of industrial benchmark Aeroxide® TiO2 P25, the formation of harmful nitrous acid (HONO) product on the Spikelet TiO2 layers was suppressed. Similarly, in the decontamination of water by organics, the mineralization of 4-chlorophenol on Spikelet layers was interestingly the same, although their reaction rate constant was three-times lower. The possible explanation may be the more than half-magnitude order higher external quantum efficacy (EQE) compared to that of the reference TiO2 P25 layer. Therefore, such favorable kinetics and reaction selectivity, together with feasible scale-up, make the hierarchical TiO2 layers very promising photocatalyst which can be used for environmental remediation