title: Release and Skin Permeation of Scopolamine From Thin Polymer Films in Relation to Thermodynamic Activity.
abstract: The object was to demonstrate if the diffusional flux of the drug out of a drug-in-adhesive-type matrix and its subsequent permeation through an excised skin membrane is a linear function of the drug's thermodynamic activity in the thin polymer film. The thermodynamic activity, ap(*), is defined here as the degree of saturation of the drug in the polymer. Both release and release/permeation of scopolamine base from 3 different poylacrylate pressure-sensitive adhesives (PSAs) were measured. The values for ap(*) were calculated using previous published saturation solubilities, wp(s), of the drug in the PSAs. Different rates of release and release/permeation were determined between the 3 PSAs. These differences could be accounted for quantitatively by correlating with ap(*) rather than the concentration of the drug in the polymer films. At similar values for ap(*) the same release or release/permeation rates from the different polymers were measured. The differences could not be related to cross-linking or presence of ionizable groups of the polymers that should influence diffusivity.
authors.affiliation: Division of Pharmaceutics, Friedrich-Alexander University, Erlangen, Germany.
authors.forename: Anders
authors.initials: A
authors.lastname: Kunst
authors.affiliation: Division of Pharmaceutics, Friedrich-Alexander University, Erlangen, Germany. Electronic address: geoff.lee@fau.de.
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Lee
mesh_terms: D000269:Adhesives / Q000737:chemistry*; D000759:Adjuvants, Anesthesia / Q000008:administration & dosage* / Q000493:pharmacokinetics; D000279:Administration, Cutaneous; D000818:Animals; D016503:Drug Delivery Systems / Q000379:methods*; D051379:Mice; D010539:Permeability; D011108:Polymers / Q000737:chemistry*; D011312:Pressure; D012601:Scopolamine / Q000008:administration & dosage* / Q000493:pharmacokinetics; D012867:Skin / Q000378:metabolism; D012869:Skin Absorption; D012995:Solubility; D013816:Thermodynamics
chemical_list: D000269:Adhesives; D000759:Adjuvants, Anesthesia; D011108:Polymers; D012601:Scopolamine
keywords: activity; solubility; transdermal