DigoxinMagnesiumMagnesium SulfateMagnesium DeficiencyMagnesium CompoundsMagnesium OxideDigitoxinCardenolidesCardiotonic AgentsCardiac GlycosidesMagnesium HydroxideMedigoxinMagnesium ChlorideEleutherococcusAnti-Arrhythmia AgentsDrug InteractionsDigitalis GlycosidesNeriumOuabainCalciumRadioimmunoassayPotassiumP-Glycoprotein