DigoxinAbsorptionIntestinal AbsorptionDigitoxinCardenolidesCardiotonic AgentsCardiac GlycosidesBiological AvailabilitySkin AbsorptionMedigoxinEleutherococcusAdministration, OralDrug InteractionsSpectrophotometry, AtomicX-Ray Absorption SpectroscopyJejunumNeriumAnti-Arrhythmia AgentsDigitalis GlycosidesP-GlycoproteinCaco-2 CellsSpectrophotometryOuabainRadioimmunoassayIronSaponinsSpectrum AnalysisIntestine, SmallQuinidine