Figure 4.

Serum drug concentrations in the eplerenone (EPL) and spironolactone (SPL) treatment groups. A: serum concentrations of canrenone, a major SPL metabolite, were determined by liquid chromatography-mass spectrometry at week 5 (n = 15), week 6 (n = 0), week 7 (n = 11), week 8 (n = 15), week 9 (n = 11), and week 10 (n = 11). B: serum concentrations of EPL and its two major metabolites were determined by liquid chromatography-mass spectrometry at week 5 (n = 15), week 6 (n = 2), week 7 (n = 12), week 8 (n = 14), week 9 (n = 10), and week 10 (n = 13). As expected, neither EPL, EPL metabolites nor canrenone were detected in the placebo group (data not shown). Likewise, canrenone was not detected in serum samples from the EPL treatment group and EPL or its metabolites were not detected in serum samples from animals treated with SPL.