[Comparative study of relative biovailability of several spironolactone formulations in a steady-state test (author's...

By the US Food and Drug Administration spironolactone is regarded as a drug with problems related to bioavailability. A steady-state study was performed comparing the 50- and 100-mg formulations of two manufacturers with each other. Applying a fluorimetric method to both canrenone and canrenoate--the major biologically active metabolites of spironolactone--the two brands were compared in 11 volunteers for the 50 mg, and in 10 volunteers for the 100 mg dosage form.