title: [Isomerisation and bioavailability of beta- and alpha-acetyldigoxin (author's transl)].
abstract: Bioavailability of acetylated derivatives of digoxin tablets have been studied in healthy subjects after a single oral and intravenous dose as well as during maintenance therapy. alpha-acetyldigoxin shows a lower bioavailability than beta-acetyldigoxin even if the alpha-acetylated derivative is incorporated in a matrix of aerosil (SiO2). Moreover, beta-acetyldigoxin can be transferred to alpha-acetyldigoxin in alkaline solutions. This isomerisation leads to a decrease of the bioavailability of such fixed preparations which contain beta-acetyldigoxin and the hygroscopic salts of potassium-magnesium-aspartate. A prevention of the isomerisation is attained by isolating beta-acetyldigoxin from potassium-magnesium-aspartate. The bioavailability of a such new formulation is comparable to that of beta-acetyldigoxin alone. The experiments show the bioavailability of acetylated derivatives of digoxin to be influenced by the physico-chemical properties of a drug and its preparation.
mesh_terms: D000107:Acetylation; D000284:Administration, Oral; D001682:Biological Availability; D004077:Digoxin / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism*; D004338:Drug Combinations; D004355:Drug Stability; D006801:Humans; D007275:Injections, Intravenous; D011195:Potassium Magnesium Aspartate; D013237:Stereoisomerism; D013810:Therapeutic Equivalency
chemical_list: D004338:Drug Combinations; D004077:Digoxin; D011195:Potassium Magnesium Aspartate
vernacular_title: Isomerisierung und biologische Verfügbarkeit von beta- und alpha-acetyldigoxin.