title: Predicting the gastrointestinal behaviour of modified-release products: utility of a novel dynamic dissolution test apparatus involving the use of bicarbonate buffers.
abstract: The establishment of physiologically relevant in vitro-in vivo correlations (IV-IVCs) is key for any biorelevant dissolution test. Historically, bicarbonate buffers have produced better correlations than compendial phosphate buffered media, though such tests are usually performed at a constant pH experiment, overlooking the notion that the pH of the luminal fluids is variable and fluctuating. In this work, we have devised a dynamic dissolution test method employing a physiological bicarbonate buffer under pH conditions of the proximal gut in order to assess the dissolution behaviour of various enteric polymer-coated (gastro-resistant) prednisolone tablets. The pH of the media is modulated and controlled by an Auto pH System™ which exploits the physiological equilibria between [H2CO3] and [HCO3(-)], to match it to the aboral change in pH with transit of the dosage form through the proximal small intestine (from pH 5.6 up to 6.8). The lag time values for an accelerated release and standard EUDRAGIT(®) L30D-55 coated formulation (25 min and 60 min, respectively) were close to the previously reported initial tablet disintegration time data obtained in-vivo by γ-scintigraphy (28 min and 66 min, respectively). Dissolution of alternative delayed release coated products was also better discriminated in the dynamic buffer system. These data confirm the dynamic dissolution system provides a robust and reliable platform to predict the in vivo fate of oral products in a laboratory setting.
authors.affiliation: Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK. Electronic address: hamid.merchant@hud.ac.uk.
authors.forename: Hamid A
authors.initials: HA
authors.lastname: Merchant
authors.affiliation: Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK.
authors.forename: Alvaro
authors.initials: A
authors.lastname: Goyanes
authors.affiliation: Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK.
authors.forename: Narendra
authors.initials: N
authors.lastname: Parashar
authors.affiliation: Department of Pharmaceutics, UCL School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, UK. Electronic address: a.basit@ucl.ac.uk.
authors.forename: Abdul W
authors.initials: AW
authors.lastname: Basit
mesh_terms: D002482:Cellulose / Q000031:analogs & derivatives / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D003692:Delayed-Action Preparations; D065546:Drug Liberation; D006863:Hydrogen-Ion Concentration; D008747:Methylcellulose / Q000031:analogs & derivatives / Q000737:chemistry; D008954:Models, Biological; D011109:Polymethacrylic Acids / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry; D011239:Prednisolone / Q000008:administration & dosage / Q000737:chemistry*; D012995:Solubility
chemical_list: D003692:Delayed-Action Preparations; D011109:Polymethacrylic Acids; D011145:Polyvinyls; C038300:methylmethacrylate-methacrylic acid copolymer; C036125:polyvinylacetate phthalate polymer; C048331:hydroxypropylmethylcellulose acetate succinate; D002482:Cellulose; C011708:cellulose acetate phthalate; D008747:Methylcellulose; C053309:hydroxypropyl methylcellulose phthalate; D011239:Prednisolone
keywords: Biorelevant dissolution; Enteric polymers; Gastro-resistant coatings; Hydrogen carbonate buffer; Physiological bicarbonate buffer; Prednisolone (PubChem CID: 5755); pH-sensitive polymers