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Formulation and evaluation of floating mucoadhesive alginate beads for targeting Helicobacter pylori.

The Journal of pharmacy and pharmacology (2014-12-17)
Adeola O Adebisi, Peter R Laity, Barbara R Conway
ABSTRACT

There are various obstacles in the eradication of Helicobacter 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 for delivery to the gastric mucosa to improve the eradication of this microorganism. Calcium alginate beads were prepared by ionotropic gelation. The formulation was modified through addition of oil and coating with chitosan to improve floating, mucoadhesion and modify drug release. Scanning electron microscopy confirmed the sphericity of the beads with X-ray microtomography showing the three-dimensional 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 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. 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. 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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Calcium chloride dihydrate, ACS reagent, ≥99%
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Calcium chloride dihydrate, ReagentPlus®, ≥99.0%
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Calcium chloride dihydrate, BioXtra, ≥99.0%
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Calcium chloride dihydrate, puriss. p.a., ACS reagent, reag. Ph. Eur., ≥99%
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Calcium chloride dihydrate, BioUltra, for molecular biology, ≥99.5% (KT)
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Calcium chloride dihydrate, puriss., meets analytical specification of Ph. Eur., USP, FCC, E509, 99-103%, ≤0.0001% Al
Sigma-Aldrich
Calcium chloride dihydrate, tested according to Ph. Eur.