Mineralocorticoid-Blocking Activity of Oral Contraceptives

I didn't learn this until recently, but some commonly used oral contraceptives--for example Yasmin-28 (the progestin-derivative drospirenone + ethinyl estradiol)--has some mineralocorticoid blocking effect, similar to that seen for spironolactone. It may therefore be associated with hyperkalemia, particularly in patients already on medications that predispose to higher serum K's. The package insert actually recommends monitoring K levels during the first month in patients receiving Yasmin who are also on ACE-I/ARBs, K-sparing diuretics, NSAIDs, or K-supplements, but this recommendation may be overlooked.