Development of gastroretentive floating granules with gentian root extract by hot-melt granulation

The roots of yellow gentian, Gentiana lutea L. (Gentianaceae) are used in traditional medicine for the treatment of gastrointestinal disorders, with the literature data indicates a local gastric effect of gentian root extract (GRE) and support the use of the solid pharmaceutical forms. Gentiopicroside, as a dominant secoiridoid in the GRE, has a short elimination half-life and low bioavailability and, consequently, its bioactivity is limited. The aim of the study was to develop gastroretentive floating delivery system with GRE, and to provide prolonged release of gentiopicroside. Floating granules with dry GRE (DGRE) were prepared by the hot-melt granulation technique, while formulations included effervescent components (citric acid and sodium bicarbonate), hydroxypropyl methylcellulose (HPMC) and meltable binders (Compritol® 888 ATO and Gelucire® 50/13). The flowability of the DGRE and prepared formulations was determined by calculating the Carr index and Hausner ratio. Floating properties and in vitro dissolution rate of gentiopicroside from investigated formulations were examined. Floating granules were characterized with improved flowability (Carr index 14-22 %; Hausner ratio 1.16-1.28) in comparison to the DGRE (Carr index 28.99 %; Hausner ratio of 1.41). Furthermore, the floating granules exhibited immediate and long-lasting buoyancy and prolonged-release of gentiopicroside (over 8 h). Compritol® 888 ATO has provided sustained release of gentiopicroside from floating granules, while HPMC has decreased release rate additionally. On the other hand, Gelucire® 50/13 has increased gentiopicroside release rate. The results have shown that hot-melt granulation technique, as a green granulation method was successfully employed for obtaining gastroretentive floating granules with DGRE.

Interaction of Oily Water with Floating Porous Ceramic and Immobilized Microorganisms

Oily water was treated with porous ceramic granules and immobilized microorganisms. Floating granules with bulk density of 0.63-0.66 g cm-3were used. The sorption of motor oil was investigated for dry and wetted granules. Respiration experiments showed that microorganisms immobilized on floating ceramic carrier and treated with oily water were influenced by agitation of liquid. The treatment of oily water with low salinity (1-9 g L-1) showed that oil removal efficiency decreased after increasing water salinity. Likewise, oil removal efficiency decreased from 12 to 9% per gram of ceramic carrier after increasing the spill of oil from 9 to 35 g per square meter. Porous granules with immobilized microorganisms can be used in cases with insignificant oil pollution or for pretreatment of wastewater before feeding it into a wastewater treatment plant.