Synthesis and characterization of dextran esters as coating or matrix systems for oral delivery of drugs targeted to the colon

Different dextran esters with various degrees of substitution (1, 2 and 3) were synthesized by esterification reaction, with three acid anhydrides: acetic anhydride, propionic anhydride, and butyric anhydride, separately. These modified polysaccharides were characterized by FT-IR, 1H NMR and 13C NMR spectroscopies. Enzymatic degradation of biopolymers by dextranase was also studied. The polymers showing the best degradation profiles were chosen to design blended free films in combination with a polymethacrylate (Eudragit® RS 30D) as a sustained release system for targeting to the colon. These free films were evaluated by permeability of theophylline used as tracer in different in vitro media of the gastro intestinal tract, in presence or in absence of dextranase. From these studies, it was concluded that dextran esters having the lower degree of substitution and constituted of short carbohydrate chains showed the best and significant enzymatic degradation and could be used as a promising carrier for specific colon drug delivery system.Keywords: Colon-Specific Drug Delivery; Polysaccharides; Dextran; Dextranase; Dextran esters; Enzymatic Degradation; Eudragit® RS 30D; Sid-by-side diffusion cel

Studying the Effect of Adding Aleppo Pylon to the Properties of Insulating and Accumulation of Polyvinyl Chloride Films

This research presents a study of the effect of adding natural and modified Aleppo Pylon (Syrian clay) in different proportions to the properties of polymeric films prepared from poly vinyl chlorid (PVC) polymer and dried at three different drying degrees (60oC, 100oC, 150oC). The clay surface was changed from hydrophilic to hydrophobic by treating the surface with quaternary alkyl ammonium salts. Both types of Aleppo Pylone were added to the polymer by weight (0%, 2.5%, 5%, 7.5%, 10%), and the polymeric films were prepared by way of mixing well of PVC polymer and clay. The mixing technique used hexanol as a solvent. The clay was mixed with the polymer at 150 Co temperature using a magnetic stirrer. The effect of adding natural and modified Aleppo Pylon to the properties of water absorption ratio, moisture content, migration of components in moderate, acidic and alkaline aqueous solutions, thermal stability and air permeability of polymeric films prepared from PVC polymer and clay with different drying degrees was studied and compared with them, in order to reach an improved PVC that can be used in the field of packaging