[Semisynthetic cellulose derivatives as the base of hydrophilic gel systems]. / Polosyntetické deriváty celulosy jako základ hydrofilních gelových systému.

The field of drug technology widely ulilizes gel systems of high-molecular substances, which have a number of advantages, such as low toxicity, availability, unique physical properties, biocompatibility, mucoadhesivity, and others. Gel systems are used in the field of local as well as general therapy, in both shape-specific and shape-non-specific dosage forms, in medicaments of the first, second, and third generations. An important group of gels employed in pharmacy are hydrophilic gels or hydrogels, most frequently composed of hydrophilic polymers of natural, semisynthetic and synthetic origin. Though cellulose derivatives as the representatives of polymers of semisynthetic origin are used in pharmaceutical technology for a long time, their research continues and their other possible uses are being searched for. Their advantages include especially safety, easy availability, and a relatively low price. The review paper describes selected cellulose derivatives, their properties and uses in pharmaceutical technology with regard to their use in the field of production of gel systems.

[Antioxidant activity of tinctures prepared from hawthorn fruits and motherwort herb]. / Antioxidacní aktivita tinktur pripravených z hlohových plodu a nati srdecníku.

The paper aimed to determine and compare the antioxidant activity of two tinctures and selected flavonoids present in the tinctures. The tinctures were prepared from hawthorn fruits and motherwort herb. The group of selected flavonoids included rutin, quercetin, hyperosid, epicatechine, and procyanidin B2. Two methods were employed to determine antioxidant activities: the inhibition of peroxynitrite-induced nitration of tyrosine was measured, and the ability to quench radicals was examined by of the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Both tinctures under study were able to quench radicals and reactive forms of oxygen and nitrogen. The motherwort herb tincture was more effective, but no direct effect of phenolic compounds on the extent of antioxidant activity was demonstrated. The total content of polyphenols in the motherwort herb tincture was higher by 163 %, nevertheless antiperoxynitrite activity was higher just by 19 % (p < 0.05), and the ability to reduce DPPH differed in both tinctures in a minimal manner. Of the individual flavonoids, the substances present in the tinctures in higher concentrations contributed most to antioxidant activity. In the hawthorn fruit tincture it was epicatechine and hyperosid, whereas in the motherwort herb tincture it was rutin.

[Thermoplastic granulation as an alternative method for the preparation of hydrophilic-lipophilic oral matriix tablets]. / Termoplastická granulace jako alternativa prípravy hydrofilne-lipofilních perorálních matricových tablet.

The paper focuses on the formulation of HPMC K-matrix tablets by compression of granulates previously prepared by melt granulation. The model drug was theophylline monohydrate. Montanglycol wax was used as the solid lipid binder in a concentration of 10-20 %. With respect to the obtained results, thermoplastic granulation was found to ensure suitable porosity, flow, and particle size of the granulates. In both dissolution media (phosphate buffer pH 6.8 and artificial gastric juice pH 1.2), the release of the model drug is dependent on the HPMC viscosity grade used. The release rate can be modified by a change in the HPMC-to-montanglycol wax ratio. A decrease in this ratio increases the liberation of theophylline monohydrate. Due to different drug solubilities in the selected dissolution media, theophylline is released significantly faster in phosphate buffer pH 6.8 then in artificial gastric juice pH 1.2. The matrices of the same composition were prepared by direct compression; the comparison of dissolution profiles shows that the release of the active substance is not influenced by the employed method of manufacture.