Just some FYI stuff:
Absorption and metabolism of spironolactone
Spironolactone is rapidly absorbed, with maximum plasma levels being reached in 30 to 60 minutes. Food increases spironolactone absorption. The percentage of drug that is detected in the systemic circulation after its oral administration exceeds 90%, depending on the tablet manufacturer.
Spironolactone is rapidly metabolized by the liver. Canrenone can be inter-converted enzymatically to its hydrolytic product, canrenoate. No un-metabolized drug is passed out via the urine. The major metabolites are canrenone and potassium canrenoate and are excreted through urine and bile.
Mechanism of spironolactone action in treatment of androgenetic alopecia
Spironolactone is a potent antiandrogen. The term antiandrogen, as defined by Dorfman, implies prevention of expression of androgen activity at target sites and does not include other mechanisms of decreasing androgen action, such as a decrease in production of androgens, interference with androgen metabolism, or change in androgen plasma protein binding.
However, the action of Spironolactone is directed at both decreasing production and blocking the effect of androgens at the cellular level. It is evident that Spironolactone decreases testosterone production in the adrenal gland by depleting microsomal cytochrome P450 and by affecting the cytochrome P450-dependent enzymes 17a-hydroxylase and desmolase. The destruction of microsomal cytochrome P450 by spironolactone may be limited to those tissues in which microsomal 17a-hydroxylase activity is high. The binding of spironolactone to 17- hydroxylase-cytochrome P450 may convert spironolactone to a metabolite that destroys the heme portion (molecule containing iron) of cytochrome P450, thereby decreasing steroid 17-hydroxylation.
Spironolactone is also a competitive inhibitor of DHT-receptor binding and interferes with the translocation of this complex into the nucleus. Spironolactone, a strong competitor for the androgen receptor, is a potent agonist, whereas canrenone, a weak competitor, is a potent antagonist. The true antagonists of endogenous or exogenous androgens are the weak agonists, which rely only on a continuous supply of the compound to achieve full inhibition. The antiandrogen effect of spironolactone may be produced by the parent compound on the adrenal gland and the metabolite on the receptor site.
The protestation activity of spironolactone is variable but influences the ratio of luteinizing hormone (LH) to follicle-stimulating hormone (FSH) by decreasing the response of LH to gonadotropin-releasing hormone (GnRH), thereby decreasing androgen production.
http://www.androgeneticalopecia.com/hair...ness.shtml