Hormones 2016

Spironolactone
Spironolactone - liquid - 5 mg/5 mL, 10 mg/5 mL, 25 mg/5 mL, 50 mg/5
mL and 100 mg/5 mL
Pharmacology
Competes with aldosterone at receptor sites in renal tubule, resulting in
excretion of sodium chloride, water, bicarbonate, and calcium, but with
retention of potassium, phosphate and hydrogen (Abramovitz, 2016).
Pharmacodynamics
Spironolactone is a synthetic 17-lactone steroid which is a renal competitive
aldosterone antagonist in a class of pharmaceuticals called potassiumsparing
diuretics. On its own, spironolactone is only a weak diuretic, but it
can be combined with other diuretics. Due to its anti-androgen effect, it can
also be used to treat hirsutism, and is a common component in hormone
therapy for male-to-female transgendered people. Spironolactone inhibits
the effect of aldosterone by competing for intracellular aldosterone receptor
in the distal tubule cells. This increases the secretion of water and sodium,
while decreasing the excretion of potassium. Spironolactone has a fairly
slow onset of action, taking several days to develop and similarly the effect
diminishes slowly (drugbank, 2013k).
Indications
Oedema and ascites in cirrhosis of the liver, malignant ascites, nephrotic
syndrome, congestive heart failure; primary hyperaldosteronism (BNF,
2016a).
Pharmacokinetics
Fairly rapidly absorbed from the gastrointestinal tract, with the extent of
its absorption depending on the particle size and formulation. Modern
formulations are reported to provide a bioavailability of about 90%, with
90% being bound to the plasma proteins. It is . Orally, onset 24–48 hours,
with its peak within 48–72 hours (Abramovitz, 2016).
Absorption - Fairly rapidly absorbed from the gastrointestinal tract. Food
increases the bioavailability of unmetabolized spironolactone by
almost 100%.
Protein binding - Spironolactone and its metabolites are more than 90%
bound to plasma proteins.
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Version 2016.3576– – Document LATEXed – 1st May 2016
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