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In vitro and in vivo testing of a gastric retention device : development and evaluation of a new colonic delivery system

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dc.contributor.advisor Ayres, James W.
dc.creator Ahmed, Iman Saad
dc.date.accessioned 2012-06-26T19:31:02Z
dc.date.available 2012-06-26T19:31:02Z
dc.date.copyright 2002-09-04
dc.date.issued 2002-09-04
dc.identifier.uri http://hdl.handle.net/1957/30202
dc.description Graduation date: 2003 en_US
dc.description.abstract This thesis describes evaluation of a gastric retention device (GRD) developed at Oregon State University. The device was originally fabricated from Xanthan gum and Locust bean gum. A modified gastric retention device containing other additives was developed and investigated in this work. The modified device was evaluated in vitro for swelling and dissolution properties using riboflavin as a model drug. Different shapes and sizes of GRDs were tested in dogs to study the gastric retention potential of these devices. The effect of the device on food emptying from the stomach in dogs was also investigated. Endoscopic studies in dogs also showed that the device swells rapidly and considerably in gastric fluid. The bioavailability of riboflavin from three different size GRDs was determined in six fasted human volunteers and compared to an immediate release formulation. The biostudy indicated that the bioavailability of riboflavin from a large size GRD was more than triple that measured after administration of the immediate release formulation. Deconvolution was used to determine gastric residence time of the different size GRDs. A new colonic delivery system made of acetaminophen loaded beads produced by extrusion and spheronization and coated with different ratios of pectin and ethylcellulose coating solutions in a spray coating apparatus was also developed in this work. Such beads release their drug content in the colon due to susceptibility of pectin in the outer coat to enzymatic action of colonic bacteria. The new delivery system was evaluated in vitro by conducting release studies in different dissolution media to mimic transit times, pH and enzyme conditions in the gastrointestinal tract. The gastrointestinal transit behavior of drug beads was also assessed by conducting gamma-scintigraphic studies in dogs. The bioavailability and pharmacokinetic parameters of acetaminophen from several colonic delivery system formulations were determined in human volunteers and compared to the immediate release commercial product Tylenol®. A selected pectin-ethylcellulose coat formulation in the ratio 1:3 was further evaluated in six volunteers under both fed and fasting conditions and was found to be effective and to provide sustained drug release in the colon over a period of 12 hours. en_US
dc.language.iso en_US en_US
dc.subject.lcsh Oral medication en_US
dc.subject.lcsh Drugs -- Controlled release en_US
dc.subject.lcsh Drug delivery systems en_US
dc.title In vitro and in vivo testing of a gastric retention device : development and evaluation of a new colonic delivery system en_US
dc.type Thesis/Dissertation en_US
dc.degree.name Doctor of Philosophy (Ph. D.) in Pharmacy en_US
dc.degree.level Doctoral en_US
dc.degree.discipline Pharmacy en_US
dc.degree.grantor Oregon State University en_US
dc.description.digitization File scanned at 300 ppi (Monochrome, 24-bit Color) using Capture Perfect 3.0.82 on a Canon DR-9080C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR. en_US
dc.description.peerreview no en_us

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