At the early stage of its development in 1957, the daily dose of
spironolactone necessary to improve various pathological conditions was not precisely determined and dose-dependent sexual side effects limited its long-term use. Prescription of high daily doses and absence of selectivity for the
mineralocorticoid receptor explain these limitations. The 9-11alpha epoxy group added to
mexrenone by the Ciba-Geigy chemists in 1984 and improved chemical synthesis at Searle, permitted the original international clinical development of a selective antagonist for
high blood pressure and
congestive heart failure treatment. This review deals with the main methodological issues of a 20-year
biological and clinical development of
eplerenone, the second antimineralocorticoid
drug. The investigation of a large range of daily doses (25-400mg) initially selected in normal volunteers by the 9alpha-fluorohydrocortisone test has led to the conclusion that 50-100mg q.i.d. doses of
eplerenone offer a favorable benefit/risk ratio in various patient populations by neutralization of the
aldosterone effects on blood pressure and target organ damage. The absence of sexual side-effects has confirmed the clinical relevance of the initial
biological hypothesis on the need for more selectivity at the
androgen and
progestogen receptor sites. Widening the distance between efficacy and adverse effects of an anti-
mineralocorticoid drug will facilitate the long-term maintenance of a moderately negative
sodium balance and a slightly positive
potassium balance, while minimizing the direct effects of
salt and
aldosterone on the heart, vessels, brain, and kidneys. Wide use in unselected patients and additional controlled clinical trials are necessary to confirm the benefits expected from animal and clinical research given that a 45-year interval also characterizes the story of the
Na-Cl cotransporter (NCC) blocker,
chlorthalidone, from its initial clinical use to the demonstration of its beneficial effects on cardiovascular morbidity and mortality.