CALCIUM-CHANNELBLOCKERS AND DIURETICS

Mild to moderate inhibitors of CYP3A4 (such as diltiazem and verapamil) cause a 2-fold increase in eplerenone levels, which increases the risks of hyperkalaemia. Additive hypotensive effects likely when calcium-channel blockers are given with any diuretic, see antihypertensives.
It is generally recommended that the dose of eplerenone should not exceed 25 mg daily in patients taking diltiazem or verapamil.