title: Formulation and evaluation of floating mucoadhesive alginate beads for targeting Helicobacter pylori.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  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.
authors.affiliation: Department of Pharmacy, School of Applied Sciences, University of Huddersfield, Huddersfield, UK.
authors.forename: Adeola O
authors.initials: AO
authors.lastname: Adebisi
authors.forename: Peter R
authors.initials: PR
authors.lastname: Laity
authors.forename: Barbara R
authors.initials: BR
authors.lastname: Conway
mesh_terms: D000268:Adhesiveness; D000464:Alginates / Q000737:chemistry*; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D017291:Clarithromycin / Q000008:administration & dosage* / Q000627:therapeutic use; D004304:Dosage Forms; D016503:Drug Delivery Systems; D005753:Gastric Mucosa / Q000378:metabolism*; D020723:Glucuronic Acid / Q000737:chemistry; D016481:Helicobacter Infections / Q000188:drug therapy* / Q000382:microbiology; D016480:Helicobacter pylori; D006603:Hexuronic Acids / Q000737:chemistry; D009077:Mucins / Q000378:metabolism
chemical_list: D000464:Alginates; D000900:Anti-Bacterial Agents; D004304:Dosage Forms; D006603:Hexuronic Acids; D009077:Mucins; D020723:Glucuronic Acid; D017291:Clarithromycin
keywords: Helicobacter pylori; calcium alginate; clarithromycin; floating dosage forms; mucoadhesion