INSPRA contains eplerenone, a blocker of aldosterone binding at the mineralocorticoid receptor.
Eplerenone is chemically described as Pregn-4-ene-7,21-dicarboxylic acid,
9,11-epoxy-17-hydroxy-3-oxo-, γ-lactone, methyl ester, (7α,11α,17α)-. Its empirical formula is
C24H30O6 and it has a molecular weight of 414.50. The structural formula of eplerenone is
represented below:
Eplerenone is an odorless, white to off-white crystalline powder. It is very slightly soluble in
water, with its solubility essentially pH-independent. The octanol/water partition coefficient
of eplerenone is approximately 7.1 at pH 7.0.
INSPRA for oral administration contains 25 mg or 50 mg of eplerenone and the following inactive
ingredients: lactose, microcrystalline cellulose, croscarmellose sodium, hypromellose, sodium
lauryl sulfate, talc, magnesium stearate, titanium dioxide, polyethylene glycol, polysorbate 80,
and iron oxide yellow and iron oxide red.