title: Transdermal absorption of L-dopa from a new system composed of two separate layers of L-dopa and hydrogel in rats.
abstract: To maintain the stability of L-dopa in hydrogel, a new system composed of two separate layers of L-dopa and hydrogel was developed. L-Dopa sheets were made by immersing L-dopa solution into wiper sheets and by lyophilizing them. Examination for stability of L-dopa in the L-dopa sheet revealed that its stability was maintained for at least 12 weeks, providing the sheet was kept at room temperature in a dark box. In a cutaneous absorption study of L-dopa in rats, an L-dopa sheet was attached to the shaved abdominal skin. A hydrogel composed of cutaneous absorption enhancers, water and ethanol, was spread on vinyl tape (hydrogel sheet), and this sheet was placed over the L-dopa sheet. L-Dopa that was administered transdermally effectively penetrated through the skin: The plasma level of L-dopa peaked at 30 min and remained high between 60 and 180 min after the cutaneous application. Our system, composed of two separated layers of L-dopa and hydrogel, enabled the stability of L-dopa to be maintained without losing transdermal absorption of L-dopa.
authors.affiliation: Department of Pharmaceutics, Hoshi University, Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Iwase
authors.forename: J
authors.initials: J
authors.lastname: Sudo
authors.forename: J
authors.initials: J
authors.lastname: Terui
authors.forename: K
authors.initials: K
authors.lastname: Kakuno
authors.forename: T
authors.initials: T
authors.lastname: Watanabe
authors.forename: K
authors.initials: K
authors.lastname: Takayama
authors.forename: T
authors.initials: T
authors.lastname: Nagai
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D015259:Dopamine Agents / Q000008:administration & dosage* / Q000097:blood; D004355:Drug Stability; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007980:Levodopa / Q000008:administration & dosage* / Q000097:blood; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012869:Skin Absorption
chemical_list: D015259:Dopamine Agents; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007980:Levodopa