title: Skin permeation and stability studies of 5-aminolevulinic acid in a new gel and patch preparation.
abstract: A new cubic gel as well as a patch system containing additional carrageenan as matrix were used as vehicles for 5-aminolevulinic acid (5-ALA). Standard diffusion experiments of 5-ALA using Franz-type diffusion cells and porcine skin were performed. Drug stability was monitored by analysing the 5-ALA content in the formulations. The analysis of 5-ALA as non-fluorescent probe was performed after chemical reaction leading to a fluorescent derivative. The 5-ALA permeation through porcine skin after 48 h was the highest from the patch formulation with 80.3% and the second highest from the cubic gel with 66.4%, however only about 40% of 5-ALA were chemical stable after 14 days storage in the patch formulation, whereas no degradation of 5-ALA was measured in the cubic gel over 90 days of observation.
authors.affiliation: Department of Pharmaceutical Technology and Biopharmaceutics, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria. Claudia.Valenta@univie.ac.at
authors.forename: C
authors.initials: C
authors.lastname: Valenta
authors.forename: B G
authors.initials: BG
authors.lastname: Auner
authors.forename: I
authors.initials: I
authors.lastname: Loibl
mesh_terms: D000268:Adhesiveness; D000279:Administration, Cutaneous; D000622:Aminolevulinic Acid / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics*; D000818:Animals; D002351:Carrageenan; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D015194:Diffusion Chambers, Culture; D004355:Drug Stability; D005079:Excipients; D005782:Gels; D066298:In Vitro Techniques; D012869:Skin Absorption; D013552:Swine; D013718:Tensile Strength
chemical_list: D005079:Excipients; D005782:Gels; D000622:Aminolevulinic Acid; D002351:Carrageenan