title: A pharmacoscintigraphic study of three time-delayed capsule formulations in healthy male volunteers.
abstract: Three time-delayed capsule (TDC) formulations were investigated in a pharmacoscintigraphic study, using a three-way crossover design in eight healthy male volunteers. Additionally, the pulsed release of a TDC was investigated with time-lapse photography, using a nondisintegrating riboflavin tablet. The photographic study indicated how the release characteristics of the TDC relied on the erosion of a tablet containing hypromellose (HPMC). Each TDC was duel radio labelled with indium-111 and technetium-99 m DTPA complexes, to observe drug release scintigraphically (theophylline was a marker compound). Three formulations, having in vitro dissolution release times of 1.8, 2.9 or 4.0 h were shown to compare favourably with mean in vivo scintigraphic release times of 2.7, 3.0 and 4.0 h for each formulation containing 20, 24 or 35% (w/w) HPMC concentrations respectively. An increase in HPMC concentration was associated with a delayed technetium release time, and followed the same rank order as the in vitro dissolution study. Observed radiolabel dispersion always occurred in the small intestine. In conclusion, the study established that the TDC performs and demonstrates an in vitro-in vivo correlation. Additionally, time and site of release were accurately visualized by gamma scintigraphy, and confirmed with determination of theophylline absorption.
authors.affiliation: Division of Pharmaceutical Sciences, Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0NR, UK. jtmcconville@mail.utexas.edu
authors.forename: Jason T
authors.initials: JT
authors.lastname: McConville
authors.forename: Lee-Ann
authors.initials: LA
authors.lastname: Hodges
authors.forename: Tamara
authors.initials: T
authors.lastname: Jones
authors.forename: Janet P
authors.initials: JP
authors.lastname: Band
authors.forename: Bridget
authors.initials: B
authors.lastname: O'Mahony
authors.forename: Blythe
authors.initials: B
authors.lastname: Lindsay
authors.forename: Alistair C
authors.initials: AC
authors.lastname: Ross
authors.forename: Alastair J
authors.initials: AJ
authors.lastname: Florence
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Stanley
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Humphrey
authors.forename: Clive G
authors.initials: CG
authors.lastname: Wilson
authors.forename: Howard N E
authors.initials: HN
authors.lastname: Stevens
mesh_terms: D000284:Administration, Oral; D000328:Adult; D002214:Capsules; D002482:Cellulose / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D002626:Chemistry, Pharmaceutical; D018592:Cross-Over Studies; D003692:Delayed-Action Preparations / Q000737:chemistry / Q000493:pharmacokinetics; D004304:Dosage Forms; D004334:Drug Administration Schedule; D015195:Drug Design; D004341:Drug Evaluation; D005079:Excipients; D005215:Fasting; D005746:Gastric Emptying / Q000502:physiology; D041981:Gastrointestinal Tract / Q000187:drug effects; D006801:Humans; D007205:Indium Radioisotopes; D007408:Intestinal Absorption; D008297:Male; D008956:Models, Chemical; D010592:Pharmaceutic Aids / Q000737:chemistry; D004364:Pharmaceutical Preparations / Q000737:chemistry; D011877:Radionuclide Imaging / Q000379:methods*; D012256:Riboflavin / Q000493:pharmacokinetics; D012995:Solubility; D013607:Tablets; D016284:Technetium Tc 99m Pentetate; D013678:Technology, Pharmaceutical / Q000379:methods; D013806:Theophylline / Q000097:blood
chemical_list: D002214:Capsules; D003692:Delayed-Action Preparations; D004304:Dosage Forms; D005079:Excipients; D007205:Indium Radioisotopes; D010592:Pharmaceutic Aids; D004364:Pharmaceutical Preparations; D013607:Tablets; D002482:Cellulose; C008079:hydroxypropylcellulose; D013806:Theophylline; D012256:Riboflavin; D016284:Technetium Tc 99m Pentetate