title: Evaluation of photochemical degradation of digoxin by Na,K-ATPase assay.
abstract: A simple Na,K-ATPase assay is described as a suitable method for testing of digoxin photodegradation. The exposure of Na,K-ATPase to the photodegraded samples exhibited reduced inhibition of the enzyme, compared to the unirradiated samples containing equal initial concentrations of drug. The degree of inhibition was dependent on the irradiation time. The concentrations of digoxin in irradiated samples were evaluated by HPLC analysis. Excellent agreement of the results obtained by both methods was observed. The investigation of the influence of irradiated samples on Na,K-ATPase inhibition revealed no side products acting as Na,K-ATPase inhibitors. The cytokinesis block micronucleus test (CBMN) was applied in order to investigate the cytotoxicity of the possible degradation products after exposure to UV irradiation. The results confirmed that the photochemical treatment did not induce the cytotoxic side products. Zero order kinetics, which was observed for digoxin photodegradation and the associated reaction mechanism are also discussed.
authors.affiliation: Vinca Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, Serbia and Montenegro. evasic@vin.bg.ac.yu
authors.forename: Vesna
authors.initials: V
authors.lastname: Vasić
authors.forename: Urh
authors.initials: U
authors.lastname: Cernigoj
authors.forename: Katarina
authors.initials: K
authors.lastname: Krinulović
authors.forename: Gordana
authors.initials: G
authors.lastname: Joksić
authors.forename: Mladen
authors.initials: M
authors.lastname: Franko
mesh_terms: D002316:Cardiotonic Agents / Q000032:analysis* / Q000494:pharmacology / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D004077:Digoxin / Q000032:analysis* / Q000494:pharmacology / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D004355:Drug Stability; D006801:Humans; D007700:Kinetics; D008027:Light; D008214:Lymphocytes / Q000187:drug effects; D015162:Micronucleus Tests; D010777:Photochemistry; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*
chemical_list: D002316:Cardiotonic Agents; D004077:Digoxin; D000254:Sodium-Potassium-Exchanging ATPase