ABSTRACT:The model of low-molecular-weight drugs has been encapsulated within alginate beads hardened with calcium chloride. The drug's release kinetic using 3% (w/v) alginate has shown a surprising behavior after 2 h, where the release kinetic was shifted from Fickian to case II transport mechanism contradicting other authors like Akihiko et al. (J Control Release 1999, 58, 21). To support this finding, we studied the swelling of dried gel beads of 2 and 3% (w/v) alginate, which showed a sudden decrease in the swelling of 3% (w/v) alginate after 2 h due to a partial bursting of the beads. This sudden bursting was clearly observed using the optical microscope to emphasize the new findings. Calcium alginate beads revealed pH sensitivity, where 2% (w/v) alginate beads showed a maximum swelling of 5000% in alkaline medium at pH 7.4, compared with a negligible swelling percent of 60% in acidic medium (pH 1.2). Accordingly, it could be a good candidate for targeting smart and low-molecular-weight drugs to the intestine.
Herein, we present a new validated potentiometric method for fluoxetine (FLX) drug monitoring. The method is based on the integration of molecular imprinting polymer (MIP) beads as sensory elements with modified screen-printed solid contact ion-selective electrodes (ISEs). A multi-walled carbon nanotube (MWCNT) was used as a nanomaterial for the ion-to-electron transduction process. The prepared MIP beads depend on the use of acrylamide (AAm) and ethylene glycol dimethacrylic acid (EGDMA) as a functional monomer and cross-linker, respectively. The sensor revealed a stable response with a Nernstian slope of 58.9 ± 0.2 mV/decade and a detection limit of 2.1 × 10−6 mol/L in 10 mmol/L acetate buffer of pH 4.5. The presented miniaturized sensors revealed good selectivity towards FLX over many organic and inorganic cations, as well as some additives encountered in the pharmaceutical preparations. Repeatability, reproducibility and stability have been studied to evaluate the analytical features of the presented sensors. These sensors were successfully applied for FLX assessment in different pharmaceutical formulations collected from the Egyptian local market. The obtained results agreed well with the acceptable recovery percentage and were better than those obtained by other previously reported routine methods.
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