Spironolactone is a prodrug with a short terminal half-life of 1.4 hours.[5][6][7] The active metabolites of spironolactone have extended terminal half-lives of 13.8 hours for 7α-TMS, 15.0 hours for 6β-OH-7α-TMS, and 16.5 hours for canrenone, and accordingly, these metabolites are responsible for the therapeutic effects of the drug.[5][6]
7α-TS and 7α-TMS have been found to possess approximately equivalent affinity for the rat ventral prostateandrogen receptor (AR) relative to that of spironolactone.[8] The affinity of 7α-TS, 7α-TMS, and spironolactone for the rat prostate AR is about 3.0 to 8.5% of that of dihydrotestosterone (DHT).[8]
7α-TMS has been found to account for around 80% of the potassium-sparing effect of spironolactone,[6][9][10] whereas canrenone accounts for the remaining approximate 10 to 25% of the potassium-sparing effect of the drug.[11]
^ abSica DA (January 2005). "Pharmacokinetics and pharmacodynamics of mineralocorticoid blocking agents and their effects on potassium homeostasis". Heart Failure Reviews. 10 (1): 23–29. doi:10.1007/s10741-005-2345-1. PMID15947888. S2CID21437788.
^ abCutler GB, Pita JC, Rifka SM, Menard RH, Sauer MA, Loriaux DL (July 1978). "SC 25152: A potent mineralocorticoid antagonist with reduced affinity for the 5 alpha-dihydrotestosterone receptor of human and rat prostate". The Journal of Clinical Endocrinology and Metabolism. 47 (1): 171–175. doi:10.1210/jcem-47-1-171. PMID263288.
^Agusti G, Bourgeois S, Cartiser N, Fessi H, Le Borgne M, Lomberget T (January 2013). "A safe and practical method for the preparation of 7α-thioether and thioester derivatives of spironolactone". Steroids. 78 (1): 102–107. doi:10.1016/j.steroids.2012.09.005. PMID23063964. S2CID8992318.