Pectin-Based Bioadhesive Delivery of Carbenoxolone Sodium for Aphthous Ulcers in Oral Cavity

The objective of this study was to prepare and evaluate the pectin-based dosage form for buccal adhesion. Carbenoxolone sodium, which is used for the treatment of aphthous ulcers in oral cavity, was used as a model drug. The pectin buccal discs were prepared by direct compression. The water uptake and erosion of pectin disc increased progressively with the swelling time. The bioadhesion of dried pectin discs decreased when either the discs were hydrated or the buccal tissue was wet with a small volume of medium. The influencing factors such as pectin type, pectin to lactose ratio, and sweetener type on the formulations were investigated. The results demonstrated that buccal discs prepared from pectin with a high degree of esterification (DE) showed a weaker and more friable characteristic than that with low DE. Decreasing pectin to lactose ratio resulted in the high dissolution rate with low bioadhesive properties. Addition of sweetener in the formulations also affected the hardness, friability, and bioadhesive properties of the discs. The pectin discs containing sweetening agent showed a higher drug release than those without sweetener. The results suggested that pectin-based bioadhesive discs could be used to deliver carbenoxolone sodium in oral cavity.     

Development and Characterization of Lyophilized Diazepam-Loaded Polymeric Micelles

Polymeric micelles were studied as delivery carriers of diazepam, a practically insoluble drug in water, for rectal administration. The diazepam-loaded polymeric micelles were developed by using poloxamer 407 (P407), poloxamer 188, and d-α-tocopheryl poly(ethylene glycol) 1000 succinate (TPGS). Among the used polymers, TPGS resulted in polymeric micelles with good characteristics for encapsulation of diazepam which had the small particle size of 8–12 nm and narrow size distribution (PI 0.053–0.275). Additionally, 7.5% w/v of TPGS could entirely entrap the desired concentration of diazepam (5 mg/mL). To improve the physical stability upon lyophilization, an addition of P407 of 1% w/v prevented aggregation, increased physical stability, and maintained chemical stability of the lyophilized powders of diazepam-loaded polymeric micelles for 3 months storage at 4°C. The rate and amount of diazepam release from TPGS polymeric micelles mainly depended on the concentration of TPGS. The release data were fitted to Higuchi''s model suggesting that the drug release mechanism was controlled by Fickian diffusion. In conclusion, 10% w/v TPGS and 1% w/v P407 were the optimum formulation of lyophilized diazepam-loaded polymeric micelles.Key words: diazepam, lyophilization, poloxamer 407, polymeric micelles, d-α-tocopheryl poly(ethylene glycol) 1000 succinate (TPGS)