Formulation and evaluation of floating mucoadhesive alginate beads for targetingHelicobacter pylori

Objectives: There are various obstacles in the eradication of Helicobacter.pylori (H. pylori) infections, including low antibiotic levels and poor accessibility of the drug at the site of the infection. This study describes the preparation and characterisation of novel floating-mucoadhesive alginate beads loaded with clarithromycin (CMN) for delivery to the gastric mucosa to improve the eradication of this micro-organism. Methods: Calcium alginate beads were prepared by ionotropic gelation. The formulation was modified through addition of oil and coating with chitosan in order to improve floating, mucoadhesion and modify drug release. Key findings: SEM confirmed the sphericity of the beads with X-ray microtomography (XμMT) showing the 3D structure of the beads with the layered internal structure of the bead and the even distribution of the drug within the bead. This formulation combined two gastro-retentive strategies and these formulations produced excellent in vitro floating, mucoadhesive and drug release characteristics. Enhanced stability of the beads in phosphate buffer raises a potential for the modified formulations to be targeted to regions of higher pH within the gastrointestinal tract with a higher pH. Drug release from these beads was sustained through an unstirred mucin layer simulating in vivo conditions under which the H. pylori resides in the gastric mucosa. Conclusions: This novel formulation will ensure retention for a longer period in the stomach than conventional formulations and control drug release, ensuring high local drug concentrations, leading to improved eradication of the bacteria

Chitosan-alginate PEC membrane as a wound dressing: Assessment of incisional wound healing

10.1002/jbm.10382Journal of Biomedical Materials Research635610-618JBMR

Chitosan-alginate films prepared with chitosans of different molecular weights

10.1002/jbm.1029Journal of Biomedical Materials Research584358-365JBMR

Surprising performance of alginate beads for the release of low-molecular-weight drugs

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. © 2010 Wiley Periodicals, Inc