title: The use of citric acid to prolong the in vivo gastro-retention of a floating dosage form in the fasted state.
abstract: Gastro-retentive dosage forms have the potential to improve local therapy and decrease the variation in bioavailability that is observed with a number of commercially available immediate and modified release preparations. In this study, a dosage form has been developed, utilising freeze-dried calcium alginate beads, designed to float on the surface of the stomach contents thus prolonging the retention time. The aim of the study was to also assess the in vivo behaviour of the radio-labelled calcium alginate beads when they were administered under fasting conditions with either water or an aqueous solution of citric acid, a potential gut transit delaying substance. The study was performed in healthy male volunteers who swallowed the radio-labelled calcium alginate beads after a 10h overnight fast. Gamma scintigraphy was selected as the method to monitor the movement of the calcium alginate beads. The volunteers consumed no further food or drink until gastric emptying of the calcium alginate beads was complete. The results indicated that prolonged gastric retention was achieved when the dosage form was administered with the citric acid solution when compared to retention in the absence of citric acid. Citric acid, therefore, has the potential to delay the gastric emptying of the calcium alginate beads when administered to fasted volunteers.
authors.affiliation: Department of Pharmacy and Pharmaceutical Sciences, University of Manchester, Manchester M13 9PL, UK.
authors.forename: Frances
authors.initials: F
authors.lastname: Stops
authors.forename: John T
authors.initials: JT
authors.lastname: Fell
authors.forename: John H
authors.initials: JH
authors.lastname: Collett
authors.forename: Luigi G
authors.initials: LG
authors.lastname: Martini
authors.forename: Harbans L
authors.initials: HL
authors.lastname: Sharma
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Smith
mesh_terms: D000328:Adult; D000464:Alginates / Q000008:administration & dosage / Q000737:chemistry; D019343:Citric Acid / Q000494:pharmacology*; D003692:Delayed-Action Preparations; D004337:Drug Carriers / Q000008:administration & dosage; D005215:Fasting; D005746:Gastric Emptying / Q000187:drug effects*; D041981:Gastrointestinal Tract / Q000000981:diagnostic imaging; D005772:Gastrointestinal Transit / Q000187:drug effects*; D020723:Glucuronic Acid / Q000008:administration & dosage / Q000737:chemistry; D006603:Hexuronic Acids / Q000008:administration & dosage / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013670:Sodium Pertechnetate Tc 99m; D012995:Solubility; D013499:Surface Properties
chemical_list: D000464:Alginates; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D006603:Hexuronic Acids; D019275:Radiopharmaceuticals; D019343:Citric Acid; D020723:Glucuronic Acid; D013670:Sodium Pertechnetate Tc 99m