Razvoj i optimizacija sustava za isporuku metoprolol sukcinata sa zadržavanjem u želucu

Metoprolol succinate (MS) gastroretentive (GR) controlled release system was formulated to increase gastric residence time leading to improved drug bioavailability. Box-Behnken model was followed using novel combinations of sodium alginate (SA), sodium carboxymethylcellulose (NaCMC), magnesium alumino metasilicate (MAS) as independent variables. Floating lag time (Flag), t25, t50, t75, diffusion exponent as dependent variables revealed that the amount of SA, NaCMC and MAS have a significant effect (p < 0.05) on t25, t50, t75 and Flag. MSGR tablets were prepared and evaluated for mass, thickness, hardness, friability, drug content and floating property. Tablets were studied for dissolution for 24 h and exhibited controlled release of MS with floating for 16 h. The release profile of the optimized batch MS01 fitted first-order kinetics (R2 = 0.9868, n = 0.543), indicating non-Fickian diffusion or anomalous transport by diffusion and swelling.U radu je opisan razvoj sustava za isporuku metoprolol sukcinata (MS) s kontroliranim oslobađanjem i produljenim vremenom zadržavanja u želucu (GR), u svrhu poboljšanja bioraspoloživosti. Primijenjen je Box-Behnkenov model, a kao zavisne varijable izabrane su nove kombinacije natrijevog alginata (SA), natrijeve soli karboksimetilceluloze (NaCMC) i magnezijevog aluminometasilikata (MAS). Vrijeme plutanja (Flag), t25, t50, t75 i difuzijski eksponent kao zavisne varijable otkrili su da količina SA, NaCMC i MAS ima značajan učinak (p < 0,05) na t25, t50, t75 i Flag. Pripravljenim tabletama određena je masa, debljina, tvrdoća, lomljivost, sadržaj ljekovite tvari i sposobnost plutanja. Oslobađanje MS praćeno je 24 h. Rezultati pokazuju da je oslobađanje kontrolirano, a vrijeme plutanja 16 h. Oslobađanje iz optimiranog pripravka MS01 slijedi kinetiku prvog reda (R2 = 0,9868, n = 0,543), što ukazuje na difuziju koja ne slijedi Fickov zakon već anomalni transport difuzijom i bubrenjem

Razvoj i vrednovanje plutajućih tableta norfloksacina s produljenim zadržavanjem u želucu

Floating matrix tablets of norfloxacin were developed to prolong gastric residence time, leading to an increase in drug bioavailability. Tablets were prepared by the wet granulation technique, using polymers such as hydroxy propyl methylcellulose (HPMCK4M, HPMCK100M) and xanthan gum. Tablets were evaluated for their physical characteristics viz., hardness, thickness, friability, and mass variation, drug content and floating properties. Further, tablets were studied for in vitro drug release characteristics for 9 hours. The tablets exhibited controlled and prolonged drug release profiles while floating over the dissolution medium. Non-Fickian diffusion was confirmed as the drug release mechanism from these tablets, indicating that water diffusion and the polymer rearrangement played an essential role in drug release. The best formulation (F4) was selected based on in vitro characteristics and was used in vivo radiographic studies by incorporating BaSO4. These studies revealed that the tablets remained in the stomach for 180 ± 30 min in fasting human volunteers and indicated that gastric retention time was increased by the floating principle, which was considered desirable for absorption window drugs.Razvijene su plutajuće tablete norfloksacina koje se produljeno zadržavaju u želucu i time povećavaju bioraspoloživost. Tablete su pripravljene metodom vlažne granulacije, koristeći hidroksipropil metilcelulozu (HPMCK4M, HPMCK100M) i ksantan gumu. Tabletama su određena fizikalna svojstva (čvrstoća, debljina, lomljivost i varijacija mase) te sadržaj ljekovite tvari i plutajuća svojstva. Nadalje, praćeno je oslobađanje ljekovite tvari in vitro tijekom 9 h. Uočeno je da je oslobađanje kontrolirano i produljeno te da tablete plutaju u ispitivanom mediju. Mehanizam oslobađanja nije slijedio Fickov zakon, što ukazuje da difuzija vode i promjene u strukturi polimera imaju bitnu ulogu u oslobađanju ljekovite tvari. Najbolja formulacija (F4) in vitro uporabljena je s dodatkom barijevog sulfata za radiografska ispitivanja in vivo. Ispitivanja na volonterima koji su apstinirali od hrane pokazala su da primjena plutajućih tableta produljuje vrijeme zadržavanja u želucu na 180 ± 30 min

Left ventricular apical diseases

There are many disorders that may involve the left ventricular (LV) apex; however, they are sometimes difficult to differentiate. In this setting cardiac imaging methods can provide the clue to obtaining the diagnosis. The purpose of this review is to illustrate the spectrum of diseases that most frequently affect the apex of the LV including Tako-Tsubo cardiomyopathy, LV aneurysms and pseudoaneurysms, apical diverticula, apical ventricular remodelling, apical hypertrophic cardiomyopathy, LV non-compaction, arrhythmogenic right ventricular dysplasia with LV involvement and LV false tendons, with an emphasis on the diagnostic criteria and imaging features

Conjugated polymers based on dicarboxylic imide-substituted isothianaphthene and their applications in solar cells

Four new polymers containing a benzo[c]thiophene-N-dodecyl-4,5-dicarboxylic imide (DIITN) unit including the homopolymer and three donor–acceptor copolymers were designed, synthesized, and characterized. For these copolymers, DIITN unit with low bandgap was selected as an electron acceptor, whereas 5,5′-(2,7-bisthiophen-2-yl)-9-(2-decyltetradecyl)-9H-carbazole), 5,5′-(3,3′-di-n-octylsilylene-2,2′-bithiophene), and 5,5′-(2,7-bisthiophen-2-yl-9,9-bisoctyl-9H-fluoren-7-yl) were chosen as the electron donor units to tune the highest occupied molecular orbital/lowest unoccupied molecular orbital (HOMO/LUMO) levels of the copolymers for better light harvesting. These polymers exhibit extended absorption in the visible and near-infrared range and are soluble in common organic solvents. The relative low lying HOMO of these polymers promises good air stability and high open-circuit voltage (Voc) for photovoltaic application. Bulk heterojunction solar cells were fabricated by blending the copolymers with [6,6]-phenyl-C61-butyric acid methyl ester or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The best power conversion efficiency of 1.6% was achieved under simulated sunlight AM 1.5G (100 mW/cm2) from solar cells containing 20 wt % of the fluorene copolymer poly[5,5′-(2,7-bisthiophen-2-yl-9,9-bisoctyl-9H-fluoren-7-yl)-alt-2,9-(benzo[c]thiophene-N-dodecyl-4,5-dicarboxylic imide)] and 80 wt % of PC71BM with a high open-circuit voltage (Voc) of 0.84 V