1. Clinical trials have demonstrated morbidity and mortality benefits of mineralocorticoid receptor antagonists (MRAs) in patients with heart failure. These studies have used either spironolactone or eplerenone as the MRA. It is generally believed that these two agents have the same effects, and the data from studies using one drug could be extrapolated for the other. National and international guidelines do not generally discriminate between spironolactone and eplerenone, but strongly recommend using an MRA for patients with heart failure due to LV systolic dysfunction and post-infarct LV systolic dysfunction. There are no major clinical trials directly comparing the efficacy of these two drugs.
2. Spironolactone and eplerenone differ in their molecular structure, pharmacokinetics, and pharmacodynamics (Table 1). Spironolactone is a non-specific MRA and, due to its structural similarity to progesterone,6 has affinity for progesterone, androgen, and glucocorticoid receptors. Eplerenone is chemically different,7 and substitution of the 17-