Spironolactone is a relatively old drug, having been introduced clinically in 1959. Some have predicted that spironolactone will be less commonly used in cardiovascular conditions (e.g., heart failure and hypertension) as the newer agents like the structurally-related compound eplerenone (also an aldosterone antagonist) are more selective and lack many of the side effects and actions of spironolactone that are undesirable in that particular patient population. However, spironolactone remains more widely used as an antiandrogen than eplerenone for patients in whom this effect is a main goal.
Spironolactone is used primarily to treat heart failure, edematous conditions such as nephrotic syndrome or ascites in patients with liver disease, essential hypertension, hypokalemia, secondary hyperaldosteronism (such as occurs with hepatic cirrhosis), and Conn's syndrome (primary hyperaldosteronism). On its own, spironolactone is only a weak diuretic because it primarily targets the distal nephron (collecting tubule), where only small amounts of sodium are reabsorbed, but it can be combined with other diuretics to increase efficacy. About one person in one hundred with hypertension has elevated levels of aldosterone; in these persons, the antihypertensive effect of spironolactone may exceed that of complex combined regimens of other antihypertensives since it targets the primary cause of the elevated blood pressure.
While loop diuretics remain first-line for most patients with heart failure, spironolactone has shown to reduce both morbidity and mortality in numerous studies and remains an important agent for treating fluid retention, edema, and symptoms of heart failure. Current recommendations from the American Heart Association are to use spironolactone in patients with NYHA Class II-IV heart failure who have a left ventricular ejection fraction of <35%.
In a randomized evaluation which studied people with severe congestive heart failure, patients treated with spironolactone were found to have a relative risk of death of 0.70 or an overall 30% relative risk reduction compared to the placebo group, indicating a significant Death and morbidity benefit of the drug. Patients in the study's intervention arm also had fewer symptoms of heart failure and were hospitalized less frequently. Likewise, it has shown benefit for and is recommended in patients who recently suffered a heart attack and have an ejection fraction <40%, who develop symptoms consistent with heart failure, or have a history of diabetes mellitus. Spironolactone should be considered a good add-on agent, particularly in those patients "not" yet optimized on ACE inhibitors and beta-blockers. Of note, a recent randomized, double-blinded study of spironolactone in patients with symptomatic heart failure with "preserved" ejection fraction (i.e. >45%) found no reduction in death from cardiovascular events, aborted cardiac arrest, or hospitalizations when spironolactone was compared to placebo.
It is recommended that alternatives to spironolactone be considered if serum creatinine is >2.5 mg/dL (221µmol/L) in males or >2 mg/dL (176.8 µmol/L) in females, if glomerular filtration rate is below 30mL/min/1.73m2, or with a serum potassium of >5.0 mEq/L given the potential for adverse events detailed elsewhere in this article. Doses should be adjusted according to the degree of renal function as well.
Because spironolactone reduces the body's production of testosterone and blocks the androgen receptors, it can cause effects associated with low testosterone levels and hypogonadism in males. For this reason, men are typically not prescribed spironolactone for any longer than a short period of time, e.g. for an acute exacerbation of heart failure. The newer drug, eplerenone has been approved by the U.S. Food and Drug Administration for treatment of heart failure, but lacks the rather potent antiandrogen effects and thus is far more suitable for men for whom long term medication is being chosen. Unlike with some other diuretics, potassium supplementation should not be administered while taking spironolactone as this may cause dangerous elevations in serum potassium levels resulting in hyperkalemia and potentially deadly cardiac arrythmias. Physicians must be careful to monitor potassium levels in both males and females who are taking spironolactone, especially during the first twelve months of use and whenever the dosage is increased.
Spironolactone is frequently used as a component of hormone replacement therapy in trans women, usually in addition to an estrogen. It is generally recommended to be prescribed at a dose of 100–200 mg per day for this purpose, though it is frequently used at doses up to 300–400 mg in cases of treatment-resistant individuals, and doses as high as 600 mg have been used in some clinical studies with additional benefits seen. Spironolactone significantly depresses plasma testosterone levels, reducing them to female/castrate levels at sufficient doses and in combination with estrogen. The clinical response consists of, among other effects, decreased male pattern body hair, the induction of breast development, feminization in general, and lack of spontaneous erections.
There are very few available options for androgen receptor antagonist drug therapy. Spironolactone, cyproterone acetate, and flutamide are the most well-known and widely used agents. Compared to cyproterone acetate, spironolactone is considerably less potent as an antiandrogen by weight and binding affinity to the androgen receptor. However, despite this, at the doses in which they are typically used, spironolactone and cyproterone acetate have been found to be generally equivalent in terms of effectiveness for a variety of androgen-related conditions; though, cyproterone acetate has shown a slight though non-statistically significant advantage in some studies. Also, it has been suggested that cyproterone acetate could be more effective in cases where androgen levels are more pronounced, though this has not been proven. Flutamide, another frequently employed antiandrogen which is a pure, selective androgen receptor antagonist, though much less potent by weight and binding affinity than either spironolactone or cyproterone acetate, has been found to be more effective than either of them as an antiandrogen when it is used at the typical treatment doses. Unfortunately, the uses of both cyproterone acetate and flutamide have been associated with hepatotoxicity, which can be severe with flutamide and has resulted in the withdrawal of cyproterone acetate from the US drug market for this indication. Gonadotropin-releasing hormone (GnRH) analogues are another very effective option for antiandrogen therapy, but have not been widely employed for this purpose due to their high cost and limited insurance coverage despite many now being available as generics. Thus, spironolactone may be the only practical, safe, and available option in many cases.
Spironolactone may put patients at a heightened risk for gastrointestinal issues like nausea, vomiting, diarrhea, cramping, and gastritis. Additionally, there has been some evidence suggesting an association between use of the drug and bleeding from the stomach and duodenum, though a causal relationship between the two has not been established. Also, it has been shown to be immunosuppressive in the treatment of sarcoidosis.
Spironolactone often increases serum potassium levels and can cause hyperkalemia, a very serious condition. Therefore, it is recommended that people using this drug avoid potassium supplements and salt substitutes containing potassium. Doctors usually recommend periodic screening of serum potassium levels and some patients may be advised to limit dietary consumption of potassium-rich foods.
Research has also shown spironolactone can interfere with the effectiveness of antidepressant treatment. As the drug acts as on antagonist on the mineralocorticoid receptor, among others, it is presumed that it reduces the effectiveness of certain antidepressants by interfering with normalization of the hypothalamic-pituitary-adrenal axis in patients receiving antidepressant therapy.
Spironolactone can also have numerous other interactions, most commonly with other cardiac and blood pressure medications.
Spironolactone is considered Pregnancy Category C by the FDA and should not be taken by pregnant women due to the high risk of birth defects and feminization of male fetuses. Likewise, it has been found to be present in the breast milk of lactating mothers and, while the effects of spironolactone or its metabolites have not been extensively studied in breast-feeding infants, it is generally recommended that women also not take the drug while nursing.
Spironolactone does not have significant affinity for either of the estrogen receptors (ERα or ERβ), nor is its low affinity for the GR thought to be of significance at clinically-relevant concentrations.
Spironolactone inhibits the effects of mineralocorticoids, namely, aldosterone, by displacing them from mineralocorticoid receptors (MR) in the cortical collecting duct of renal nephrons. This decreases the reabsorption of sodium and water, while decreasing the secretion of potassium, and thus producing a mild diuretic effect. The drug has a slightly delayed onset of action, and so it takes several days for diuresis to occur. This is because the MR is a nuclear receptor which works through regulating gene transcription and gene expression, in this case to decrease the production and expression of ENaC and ROMK electrolyte channels in the distal nephrons. In addition to direct antagonism of the MRs, the antimineralocorticoid effects of spironolactone may also in part be mediated by direct inactivation of steroid 11β-hydroxylase and aldosterone synthase (18-hydroxylase), enzymes involved in the biosynthesis of mineralocorticoids. If levels of mineralocorticoids are decreased then there are lower circulating levels to compete with spironolactone to influence gene expression as mentioned above.
Spironolactone has been shown to inhibit steroid 11β-hydroxylase, an enzyme that is essential for the production of the glucocorticoid hormone cortisol. Because of this, glucocorticoid levels would in theory be lowered alongside the lower levels of mineralocorticoids (i.e. spironolactone should also produce some degree of antiglucocorticoid effect). In clinical practice however, this has not been found to be the case, as spironolactone has actually been shown to increasecortisol levels, both with acute and chronic administration. Research has shown that this is due to antagonism of the MR, which suppresses negative feedback on the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis positively regulates the secretion of adrenocorticotropic hormone (ACTH), which in turn signals the adrenal glands – the major source of corticosteroid biosynthesis in the body – to increase production of glucocorticoids as well. Therefore, by disinhibiting the regulation on ACTH, its levels rise and spironolactone essentially causes an indirect rise in cortisol production. Thus, any antiglucocorticoid activity of spironolactone via direct suppression of glucocorticoid synthesis (at the level of the adrenals) appears to be more than fully offset by its concurrent indirect stimulatory effects on glucocorticoid production secondary to ACTH.
Spironolactone mediates its antiandrogenic effects via a variety of actions, which include the following:
Direct blockade of androgens from interacting with the androgen receptor. It should be noted however that spironolactone, similarly to other steroidal antiandrogens such as cyproterone acetate, is not a pure, or silent, antagonist of the androgen receptor, but rather a weak partial agonist with the capacity for both agonist and antagonist effects. However, in the presence of significant enough levels of potent full agonists like testosterone and DHT, the cases in which it is usually used even with regards to the "lower" relative levels present in females, spironolactone will behave similar to a pure antagonist. Nonetheless, there may still be a potential for spironolactone to produce androgenic effects (i.e. act as a receptor agonist) in the body at sufficiently high doses and/or in those with low enough endogenous androgen concentrations. As an example, one condition in which spironolactone is contraindicated is prostate cancer, as the drug has been shown in vitro to significantly accelerate carcinoma growth in the absence of any other androgens, and was found to do so at the relatively high rate of approximately 32%, which was about 35% that of DHT (thus also indicating that its potential intrinsic activity at the androgen receptor may be somewhere around one-third that of endogenous full agonists).
Inhibition of 5α-reductase, the enzyme responsible for converting testosterone into the 3- to 10-fold more potent androgen dihydrotestosterone (DHT). However, there is conflicting data on the ability of spironolactone to affect this enzyme. An in vitro study of the effect of spironolactone on prostatetissue 5α-reductase activity found no change even with very high concentrations of the drug. In contrast, another study, after one month of treatment of spironolactone at a dose of 100 mg per day via the oral route, found a significant in vivo inhibitory effect of spironolactone on genital skin 5α-reductase activity in hirsute women as well as an inhibitory effect of the drug on 5α-reductase activity in normal genital skin in vitro, and concluded that spironolactone directly inhibits the 5α-reductase enzyme and that the property could play a role of the beneficial effects of the drug on hirsutism. However, another study of spironolactone in hirsute women, after 6 months of treatment at the same dose (100 mg/d orally), found no significant effects of the drug on the serum ratios of testosterone to DHT and its metabolites—a reliable marker of 5α-reductase activity—whereas significant changes were found with 5 mg per day oral finasteride, a well-established 5α-reductase inhibitor. Finally, yet another study of spironolactone in hirsute women, after 3 months of treatment at a higher dose of 200 mg per day orally, did report significant changes, in the same metabolic markers of 5α-reductase activity. In summation then, whether spironolactone actually inhibits 5α-reductase to some clinical end-point or not and how it may do so remain unclear. It can be deduced from comparison studies, however, that if it does have an effect at reducing hirsutism, it is not as effective as more potent and selective 5α-reductase inhibitors like finasteride. Supporting this conclusion is another trial in which the combination of 100 mg/d spironolactone and 5 mg/d finasteride was found to be significantly more effective than spironolactone alone in the treatment of hirsutism in women.
Acceleration of the rate of metabolism/clearance of testosterone by enhancing the rate of peripheral conversion of testosterone to estradiol.
Spironolactone has some estrogenic effects which it mediates via several indirect actions, including the following:
By acting as an antiandrogen, since androgens suppress both estrogen production and activity.
Displacement of estrogens from sex hormone-binding globulin (SHBG). This occurs because spironolactone binds to SHBG at a relatively high rate, as do endogenous estrogens and androgens, but estrogens like estradiol and estrone are more easily displaced than are androgens like testosterone. As a result, spironolactone blocks relatively more estrogens from interacting with SHBG than it does androgens, resulting in a higher ratio of free estrogens to free androgens.
Inhibition of the conversion of estradiol to estrone, resulting in an increase in the ratio of estradiol to estrone. This is relevant because estradiol is approximately 10 times as potent as estrone as an estrogen.
Enhancement of the rate of peripheral conversion of testosterone to estradiol, resulting in lower testosterone and higher estradiol levels.
Spironolactone has an onset of action of about 2–3 hours after taking the first dose, with a half-life of about 1–2 hours. Due to its relatively short half-life, it is thought that spironolactone may behave mainly as a prodrug to an array of active metabolites with much longer half-lives (e.g., 12–20 hours in the case of canrenone). Some of its metabolites include canrenone, 7α-methylthiospironolactone, and 6β-hydroxy-7α-methylthiospironolactone, among many others. The drug is highly plasma protein bound. It is metabolized by the liver, from which it is partially eliminated with the majority being handled by the kidneys. Minimal amounts are handled by biliary excretion.
Of note, the clinical benefits of the drug when used a diuretic are typically not seen until 2–3 days after dosing begins, perhaps accounted for by the need for 4-5 doses before reaching a steady state concentration. Likewise, the maximal antihypertensive effective may not be seen for 2–3 weeks.
Long-term administration of spironolactone gives the histologic characteristic of spironolactone bodies in the adrenal cortex. Spironolactone bodies are eosinophilic, round, concentrically laminated cytoplasmic inclusions surrounded by clear halos in preparations stained with hematoxylin and eosin.
Spironolactone can be synthesized from 3-hydroxyandrost-5-en-17-one (DHEA).
Spironolactone is the 7-acetate of the γ-lactone of 17-hydroxy-7-mercapto-3-oxo-17-α-pregn-4-ene-21-carboxylic acid (21.5.8). Spironolactone is synthesized industrially in two different ways from androstenolone—3β-hydroxy-5-androsten-17-one.
According to the first method, androstenolone undergoes ethynylation by acetylene in a Normant reaction condition using sodium amide in liquid ammonia, which forms 17α-ethynyl-3β-,17β-dihydroxy-5-androstene. Subsequent reaction of this with methylmagnesiumbromide and then with carbon dioxide gives the corresponding propenal acid. Reduction of the triple bond in this product with hydrogen using a palladium on calcium carbonate catalyst forms the corresponding acrylic acid derivative, which is treated with acid without being isolated, which leads to cyclization into an unsaturated lactone derivative. The double bond is reduced by hydrogen, in this case using a palladium on carbon catalyst. The resulting lactone undergoes oxidation in an Oppenauer reaction, giving an unsaturated keto-derivative—4-androsten-3,17-dione. Further oxidation of the product using chloroanyl gives dienone, which when reacted with thioacetic acid gives the desired spionolactone.
Cella, J. A.; Tweit, R. C. (1959). "Steroidal Aldosterone Blockers. II1". The Journal of Organic Chemistry24 (8): 1109. doi:10.1021/jo01090a019.edit
Dodson, R. M.; Tweit, R. C. (1959). "Addition of Alkanethiolic Acids to Δ1,4-3-Oxo- and Δ4,6-3-Oxosteroids1". Journal of the American Chemical Society81 (5): 1224. doi:10.1021/ja01514a052.edit
one of the synthesis to spirolactone
The second way is from 4-androsten-3,17-dione, which undergoes ethynylation by propargyl alcohol in the presence of potassium tert-butylate, forming 17β-hydroxy-17α-(3-hydroxypropinyl)-4-androsten-3-one, the triple bond of which is completely reduced by hydrogen using as a catalyst a complex of triphenylphospine and rhodium chloride, which forms 17β-hydroxy-17α-(3-hydroxypropyl)-4-androsten-3-one. Oxidation of this product with chromium (VI) oxide in pyridine gives lactone, which is oxidized in the manner described above by chloranyl to and reacted further with thioacetic acid to the desired spironolactone.
^ abYancy, CW; Jessup, M; Bozkurt, B; Butler, J; Casey DE, Jr; Drazner, MH; Fonarow, GC; Geraci, SA; Horwich, T; Januzzi, JL; Johnson, MR; Kasper, EK; Levy, WC; Masoudi, FA; McBride, PE; McMurray, JJ; Mitchell, JE; Peterson, PN; Riegel, B; Sam, F; Stevenson, LW; Tang, WH; Tsai, EJ; Wilkoff, BL; American College of Cardiology, Foundation; American Heart Association Task Force on Practice, Guidelines (Oct 15, 2013). "2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines.". Journal of the American College of Cardiology62 (16): e147–239. PMID23747642.Cite uses deprecated parameters (help)
^Yancy CW, Jessup M, Bozkurt B, et al. (October 2013). "2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines". J. Am. Coll. Cardiol.62 (16): e147–239. doi:10.1016/j.jacc.2013.05.019. PMID23747642.Cite uses deprecated parameters (help)
^ abPrior JC, Vigna YM, Watson D (February 1989). "Spironolactone with physiological female steroids for presurgical therapy of male-to-female transsexualism". Archives of Sexual Behavior18 (1): 49–57. doi:10.1007/bf01579291. PMID2540730.
^Gökmen O, Senöz S, Gülekli B, Işik AZ (August 1996). "Comparison of four different treatment regimes in hirsutism related to polycystic ovary syndrome". Gynecological Endocrinology : the Official Journal of the International Society of Gynecological Endocrinology10 (4): 249–55. doi:10.3109/09513599609012316. PMID8908525.
^Grigoriou O, Papadias C, Konidaris S, Antoniou G, Karakitsos P, Giannikos L (April 1996). "Comparison of flutamide and cyproterone acetate in the treatment of hirsutism: a randomized controlled trial". Gynecological Endocrinology : the Official Journal of the International Society of Gynecological Endocrinology10 (2): 119–23. doi:10.3109/09513599609097901. PMID8701785.
^Rigalli JP, Ruiz ML, Perdomo VG, Villanueva SS, Mottino AD, Catania VA (July 2011). "Pregnane X receptor mediates the induction of P-glycoprotein by spironolactone in HepG2 cells". Toxicology285 (1-2): 18–24. doi:10.1016/j.tox.2011.03.015. PMID21459122.Cite uses deprecated parameters (help)
^Christians U, Schmitz V, Haschke M (December 2005). "Functional interactions between P-glycoprotein and CYP3A in drug metabolism". Expert Opin Drug Metab Toxicol1 (4): 641–54. doi:10.1517/17425255.1.4.641. PMID16863430.Cite uses deprecated parameters (help)
^Bendtzen, K.; Hansen, P. R.; Rieneck, K. (2003). "Spironolactone inhibits production of proinflammatory cytokines, including tumour necrosis factor-alpha and interferon-gamma, and has potential in the treatment of arthritis". Clinical and Experimental Immunology134 (1): 151158. doi:10.1046/j.1365-2249.2003.02249.x. ISSN0009-9104.
^ abLuthy IA, Begin DJ, Labrie F (November 1988). "Androgenic activity of synthetic progestins and spironolactone in androgen-sensitive mouse mammary carcinoma (Shionogi) cells in culture". Journal of Steroid Biochemistry31 (5): 845–52. doi:10.1016/0022-4731(88)90295-6. PMID2462135.
^Miles RA, Cassidenti DL, Carmina E, Gentzschein E, Stanczyk FZ, Lobo RA (October 1992). "Cutaneous application of an androstenedione gel as an in vivo test of 5 alpha-reductase activity in women". Fertility and Sterility58 (4): 708–12. PMID1426314.
^Overdiek HW, Merkus FW (November 1986). "Influence of food on the bioavailability of spironolactone". Clinical Pharmacology and Therapeutics40 (5): 531–6. PMID3769384.
^Melander A, Danielson K, Scherstén B, Thulin T, Wåhlin E (July 1977). "Enhancement by food of canrenone bioavailability from spironolactone". Clinical Pharmacology and Therapeutics22 (1): 100–3. PMID872489.