title: Delayed release tablet dissolution related to coating thickness by terahertz pulsed image mapping.
abstract: Delayed release dosage forms such as Asacol employ coatings that are engineered to breakdown and release the drug topically at the nominal pH of the lower intestinal tract. Asacol tablets were found to dissolve in an erratic fashion when they are dissolved in buffers below pH 7 which can occur naturally. In this study Terahertz pulsed imaging (TPI) was used to accurately map the coating thickness of a group of Asacol tablets that were subsequently dissolved using the USP method at pH 6.8. The mean dissolution times were found to correlate with the average coating thickness measured over all surfaces. Thickness values for a single randomly selected face did not correlate well with the dissolution results. The speed and ease of TPI mapping may make it an attractive replacement for wet dissolution testing both in product development and eventually for process analysis.
authors.affiliation: U.S. Food & Drug Administration, Division of Pharmaceutical Analysis, 1114 Market Street, St. Louis, Missouri 63101, USA. John.Spencer@fda.hhs.gov
authors.forename: John A
authors.initials: JA
authors.lastname: Spencer
authors.forename: Zongming
authors.initials: Z
authors.lastname: Gao
authors.forename: Terry
authors.initials: T
authors.lastname: Moore
authors.forename: Lucinda F
authors.initials: LF
authors.lastname: Buhse
authors.forename: Philip F
authors.initials: PF
authors.lastname: Taday
authors.forename: David A
authors.initials: DA
authors.lastname: Newnham
authors.forename: Yaochun
authors.initials: Y
authors.lastname: Shen
authors.forename: Alessia
authors.initials: A
authors.lastname: Portieri
authors.forename: Ajaz
authors.initials: A
authors.lastname: Husain
mesh_terms: D003692:Delayed-Action Preparations; D006863:Hydrogen-Ion Concentration; D019804:Mesalamine / Q000008:administration & dosage / Q000737:chemistry; D012995:Solubility; D013607:Tablets; D013678:Technology, Pharmaceutical
chemical_list: D003692:Delayed-Action Preparations; D013607:Tablets; D019804:Mesalamine