In Vitro and In Vivo Evaluation of Casein as a Drug Carrier for Enzymatically Triggered Dissolution Enhancement from Solid Dispersions.

Due to its unique properties, such as biodegradability, biocompatibility, high amphiphilic property, and micelle formation, casein (CS) has been increasingly studied for drug delivery. We used CS as a drug carrier in solid dispersions (SDs) and evaluated the effect of its degradation by trypsin on drug dissolution from the dispersions. SDs of CS and mefenamic acid (MA) were prepared by physical mixing, kneading, and coprecipitation methods. In comparison to pure MA, the dispersions were evaluated for drug-protein interaction, loss of drug crystalinity, and drug morphology by differential scanning calorimetry, X-ray diffractometry, Fourier transform infrared spectroscopy, and scanning electron microscopy. Drug dissolution from the dispersions was evaluated in simulated intestinal fluid as enzyme free and trypsin-enriched media. Furthermore, in vivo drug absorption of MA from CS-MA coprecipitate was evaluated in rats, in comparison with a reference SD of polyethylene glycol and MA (PEG-MA SD). Relative to other CS preparations, CS-MA coprecipitate showed the highest loss of drug crystallinity, drug micronization, and CS-MA interaction. CS remarkably enhanced the dissolution rate and extent of MA from the physical and kneaded mixtures. However, the highest dissolution enhancement was obtained when MA was coprecipitated with CS. Trypsin that can hydrolyze CS during dissolution resulted in further enhancement of MA dissolution from the physical and kneaded mixtures. However, a corresponding retardation effect was obtained for the coprecipitate. In correlation with in vitro drug release, CS-MA coprecipitate also showed significantly higher MA bioavailability in rats than PEG-MA SD.

Electrode effects on temporal changes in electrolyte pH and redox potential for water treatment.

The performance of electrochemical remediation methods could be optimized by controlling the physicochemical conditions of the electrochemical redox system. The effects of anode type (reactive or inert), current density and electrolyte composition on the temporal changes in pH and redox potential of the electrolyte were evaluated in divided and mixed electrolytes. Two types of electrodes were used: iron as a reactive electrode and mixed metal oxide coated titanium (MMO) as an inert electrode. Electric currents of 15, 30, 45 and 60 mA (37.5 mA L(-1), 75 mA L(-1), 112.5 mA L(-1) and 150 mA L(-1)) were applied. Solutions of NaCl, Na(2)SO(4) and NaHCO(3) were selected to mimic different wastewater or groundwater compositions. Iron anodes resulted in highly reducing electrolyte conditions compared to inert anodes. Electrolyte pH was dependent on electrode type, electrolyte composition and current density. The pH of mixed-electrolyte was stable when MMO electrodes were used. When iron electrodes were used, the pH of electrolyte with relatively low current density (37.5 mA L(-1)) did not show significant changes but the pH increased sharply for relatively high current density (150 mA L(-1)). Sulfate solution showed more basic and relatively more reducing electrolyte conditions compared to bicarbonate and chloride solution. The study shows that a highly reducing environment could be achieved using iron anodes in divided or mixed electrolytes and the pH and redox potential could be optimized using appropriate current and polarity reversal.

A generalized model for transport of contaminants in soil by electric fields.

A generalized model applicable to soils contaminated with multiple species under enhanced boundary conditions during treatment by electric fields is presented. The partial differential equations describing species transport are developed by applying the law of mass conservation to their fluxes. Transport, due to migration, advection and diffusion, of each aqueous component and complex species are combined to produce one partial differential equation that describes transport of the total analytical concentrations of component species which are the primary dependent variables. This transport couples with geochemical reactions such as aqueous equilibrium, sorption, precipitation and dissolution. The enhanced model is used to simulate electrokinetic cleanup of lead and copper contaminants at an Army Firing Range. Acid enhancement is achieved by the use of adipic acid to neutralize the basic front produced for the cathode electrochemical reaction. The model is able to simulate enhanced application of the process by modifying the boundary conditions. The model showed that kinetics of geochemical reactions, such as metals dissolution/leaching and redox reactions, may be significant for realistic prediction of enhanced electrokinetic extraction of metals in real-world applications.