[Biological availability of digoxin and beta-methyl-digoxin administered in the fasting state or after meals]

Ten healthy volunteers were given 0.75 mg digoxin and 0.5 mg beta-methyl-digoxin (BMD) in tablet form in the fasting state or after breakfast. Serum concentrations and 24-hour urine excretion of glycoside were measured by radioimmunoassay. Neither the mean area under the serum concentration curve nor the mean cumulative urinary excretion was significantly changed by postprandial administration. Peak serum concentrations were higher when the subjects took the tablets while fasting than when they took them postprandially, but the difference was significant only for BMD. After BMD in the fed state the peak serum concentration was reached earlier and with less variation than after digoxin, but -- as after administration in the fasting state -- the differences were not significant. The peak serum concentration and the time when it is achieved are, as parameters for the rate of absorption, only of secondary importance for treatment with cardiac glycosides in medical practice. They suggest faster absorption of BMD compared with digoxin. Both the glycosides can be given equally well before, during or after food, a fact which facilitates prescription.