Mode of spironolactone anti-androgenic action: inhibition of androstanolone binding to rat prostate androgen receptor

Case report: A pregnant woman accidental treated with spironolactone in mid-gestation

Spironolactone, a potassium-sparing diuretic, is used to treat hypertension, heart failure, and certain hyperandrogenic disorders. Its use during pregnancy is not recommended due to the risk of feminizing male fetuses, primarily because of its antiandrogenic activity. However, human data remain scarce and largely inconclusive. Here, we present the first case of a 25-year-old pregnant woman, at 16 weeks of gestation, who was inadvertently exposed to spironolactone (240 mg/day) for 1 week due to a pharmacy dispensing error. The patient subsequently delivered a healthy male infant with normal genitalia at 38 weeks of gestation following vaginal delivery. Current follow-up shows that the infant is healthy and developing normally. This article summarizes the potential causes of spironolactone-induced anomalous genital development and explores the safety of new-generation mineralocorticoid receptor antagonists (MRAs) during pregnancy. The mechanisms behind spironolactone-induced anomalous genital development in male fetuses have not been fully elucidated. Spironolactone competes with dihydrotestosterone for binding to androgen receptors and inhibits enzymes involved in androgen biosynthesis, which may partly explain its antiandrogenic effects. Recent advancements in MRAs have led to the development of compounds with higher selectivity for the mineralocorticoid receptor, thereby reducing the incidence of antiandrogen side effects. These new-generation MRAs may be effective alternatives during pregnancy, but more data are needed to establish their safety in pregnant women. This case contributes to the limited but growing body of literature on the safety profile of spironolactone in pregnancy, providing insights into its effects during a critical period of fetal development.

Topical Treatment of Human Skin and Cultured Keratinocytes with High-Dose Spironolactone Reduces XPB Expression and Induces Toxicity

Spironolactone (SP) is used to treat a variety of disparate disease states ranging from heart failure to acne through antagonism of the mineralocorticoid and androgen receptors. Although normally taken as an oral medication, recent studies have explored the topical application of SP onto the skin. However, because SP induces the proteolytic degradation of the XPB protein, which plays critical roles in DNA repair and transcription, there may be safety concerns with the use of topical SP. In this study, we show that the topical application of a high concentration of either SP or its metabolite canrenone onto human skin ex vivo lowers XPB protein levels and induces toxic responses in the epidermis. Interestingly, although SP and canrenone both inhibit cell proliferation, induce replication stress responses, and stimulate apoptotic signaling at high concentrations in cultured keratinocytes in vitro, these effects were not correlated with XPB protein loss. Thus, high concentrations of SP and canrenone likely inhibit cell proliferation and induce toxicity through additional mechanisms to XPB proteolytic degradation. This work suggests that care may need to be taken when using high concentrations of SP directly on human skin.

A systematic review of antiandrogens and feminization in transgender women

Antiandrogens are frequently used with estradiol in transgender women seeking feminization. Antiandrogens act by various mechanisms to decrease the production or effects of testosterone, but it is unclear which antiandrogen is most effective at feminization. A systematic review was performed using PRISMA guidelines. We searched online databases (Medline, Embase and PsycINFO) and references of relevant articles for studies of antiandrogens in transgender women aged 16+ years to achieve feminization (namely changes in breast size, body composition, facial or body hair) or changes in serum total testosterone concentration when compared to placebo, estradiol alone or an alternative antiandrogen. Four studies fulfilled eligibility criteria and were included in a narrative review. The addition of cyproterone acetate, leuprolide and medroxyprogesterone acetate may be more effective than spironolactone or estradiol alone at suppressing the serum total testosterone concentration. Body composition changes appear similar in transgender women treated with estradiol and additional cyproterone acetate or leuprolide. No eligible studies adequately evaluated the effects of antiandrogens on breast development or facial and body hair reduction. It remains unclear which antiandrogen is most effective at achieving feminization. Cyproterone acetate, medroxyprogesterone acetate and leuprolide may be more effective than spironolactone at suppressing the serum total testosterone concentration. However, due to spironolactone's antagonism of the androgen receptor, it is unclear whether this results in clinically meaningful differences in feminization. Further research with clinically meaningful endpoints is needed to optimize the use of antiandrogens in transgender women.

Spironolactone and XPB: An Old Drug with a New Molecular Target

Spironolactone (SP) is commonly used for the treatment of heart failure, hypertension, and complications of cirrhosis by antagonizing the mineralocorticoid receptor. However, SP also antagonizes the androgen receptor, and thus SP has also been shown to be effective in the treatment of acne, hair loss, and hirsutism in women. Interestingly, recent drug repurposing screens have identified new and diverse functions for SP as a simulator of tumor immunosurveillance and as an inhibitor of DNA repair and viral infection. These novel pharmacological effects of SP have all been linked to the ability of SP to induce the rapid proteolytic degradation of the xeroderma pigmentosum group B (XPB) protein. XPB is a critical enzymatic component of the multi-subunit complex known as transcription factor II-H (TFIIH), which plays essential roles in both DNA repair and the initiation of transcription. Given the critical functions for XPB and TFIIH in these processes, the loss of XPB by SP could lead to mutagenesis. However, the ability of SP to promote cancer stem cell death and facilitate immune recognition may counteract the negative consequences of SP to mitigate carcinogenic risk. Thus, SP appears to have new and interesting pharmacological effects that may extend its potential uses.

The emerging role of aldosterone/mineralocorticoid receptors in the pathogenesis of erectile dysfunction

PURPOSE

Aldosterone is an old hormone that has been discovered for more than fifty years. The clinical application of its receptors' inhibitors, especially spirolactone, has benifited patients for decades worldwide. In this review, we briefly summarized the molecular mechanism of aldosterone/mineralocorticoid receptors (Ald-MRs) signaling in cardiovascular diseases and its emerging role in erectile dysfunction.

METHODS

We searched PubMed, Web of Science, and Scopus for manuscripts published prior to December 2017 using key words " aldosterone " AND " erectile dysfunction " OR " cardiovascular disease " OR " mineralocorticoid receptors ". Related literature and clinical perspectives were collated, summarized and discussed in this review.

RESULTS

The increase of reactive oxygen species production, inhibition of endothelial nitric oxide synthase system, and induction of inflammation are ubiquitous in vascular endothelial cells or vascular smooth muscle cells after the activation of Ald-MRs pathway. In addition, in cardiovascular diseases with over-active Ald-MRs signaling, MRs blockade could reverse the injury and improve the prognosis. Notably, multiple studies have correlated aldosterone and MRs to the pathogenesis of erectile function, while the mechanism is largely unperfectly identified.

CONCLUSION

In conclusion, we summarize the current evidence to highlight the potential role of aldosterone in erectile dysfunction and provide critical insights into the treatment of the disease.

Antialdosterones: incidence and prevention of sexual side effects

The use of spironolactone in the treatment of hypertension has been limited by the occurrence of sexual side effects, mainly menstrual disturbances in women and gynaecomastia in men. In order to minimize this limitation on the use of an effective potassium-sparing antihypertensive agent, two strategies can be proposed: (1) A decrease in the daily dose of spironolactone. In 182 patients with essential hypertension treated with spironolactone alone for a mean follow-up period of 23 months, daily doses of 75-100 mg were as effective on blood pressure as doses of 150-300 mg. In contrast, the development of gynaecomastia--91 cases among 699 men--was dose-related in 6.9% (50 mg/day) to 52.2% (150 mg or more/day) of the cases. (2) An improvement in the receptor-binding specificity of spironolactone. Three 9 alpha, 11 alpha-epoxy derivatives have been characterized in vitro in rats and in rabbits. They exhibited a 3- to 10-fold decrease of the antiandrogenic and progestagenic effect, compared with spironolactone. In humans, one of these derivatives counteracted the fall in urinary Na/K ratio induced by 9 alpha-fluorohydrocortisone at a 25 mg dose.

11 beta-substituted steroids, an original pathway to antihormones

11 beta-substituted steroids form a novel class of derivative for the study of ligand-receptor interactions. The present review describes the synthetic pathways leading to 11 beta-substituted norsteroids and the kinetics and specificity of their interaction with receptors of several hormone classes as determined in a routine screening programme. The biochemical data on the interaction of one of these compounds, RU 38486, a potent antihormone presently in clinical development, with the progestin (PR) and glucocorticoid (GR) receptors are briefly reviewed. The comparison of the 3D-structures of these antagonists with those of potent hormones can help to map the interaction sites with PR and GR and highlights the potential use of these molecules as labelling agents and molecular probes.

The effects of two doses of spironolactone on serum androgens and anagen hair in hirsute women

Spironolactone (S) has been used successfully for the treatment of hirsutism. We evaluated whether the effects of S on serum androgens and hair growth are dose-related and whether S affects secreted androgens to the same degree as peripherally derived androgens. Two groups of 15 hirsute patients, similarly matched, received either 100 or 200 mg S daily for 3 months. Serum total testosterone (T) decreased significantly (P less than 0.05) and to a similar degree with both dosages, whereas unbound T was unaltered. Dehydroepiandrosterone sulfate was unaltered, whereas androstenedione decreased with 200 mg S (P less than 0.05). Peripherally derived serum dihydrotestosterone decreased to a similar degree with 100 and 200 mg S (P less than 0.05), whereas 5 alpha-androstane-3 alpha-17 beta-diol (3 alpha-diol) increased (P less than 0.05) similarly with both dosages. Serum 3 alpha-diol glucuronide (3 alpha-diol-G) increased with both dosages, but not significantly. Anagen hair shaft diameters decreased significantly in both groups by 19% +/- 8% and 30% +/- 4% (P less than 0.05). No correlation was found between hair growth and serum androgens. Because serum unbound T was largely unaltered by S, it is suggested that the antiandrogenic effects of S are primarily related to its peripheral effect. However, there is no good clinical marker for this effect as levels of 3 alpha-diol and 3 alpha-diol-G increase.

Metabolism of spirolactones by the rat testis in vitro

Spironolactone (SPIR) has been shown in numerous clinical studies to produce sexual disorders. We studied the metabolism of canrenone (CAN), the main metabolite of SPIR, and of the analogue 6,7-dihydrocanrenone (DHC) by the rat testis in vitro. The metabolites produced during a 4 h incubation period were isolated by HPLC and identified by nmr-, ms-, ir- and uv-spectrometry. SPIR was not metabolised in a detectable amount. CAN was converted to canrenoic acid, several hydroxylated (15 beta-, 16 alpha-, 19-, 2OR- and 21S-OH-CAN) and one reduced metabolite (3 alpha-OH-CAN). When DHC was incubated, an analogous pattern was detected. It is concluded that CAN and DHC serve as substrates for steroid metabolism in the rat testis.

Inhibition of androgen binding in human foreskin fibroblasts by antiandrogens

Antiandrogen effects on androgen receptor binding and androgen metabolism were studied in cultured human newborn foreskin fibroblasts. Three different antiandrogens were tested in this system: (a) cyproterone acetate (CA); (b) RU23908; and (c) R2956. CA and R2956 were equipotent inhibitors of androgen binding to its intracellular receptor. The magnitude of this action was nearly twice as great against the endogenous androgen ligands, dihydrotestosterone (DHT) or testosterone (T), than with the synthetic ligand, methyltrienolone (R1881). Whereas the relative binding affinities of CA and R2956 were approximately 5-10 times less than T or DHT, RU23908 was another order of magnitude less effective as an inhibitor of androgen binding. The lower relative binding affinity determined for RU23908 could not be explained on the basis of a requirement for metabolic activation. Subcellular fractionation studies and sucrose density gradient analysis further confirmed the rank order of antiandrogenic potency. None of the antiandrogens influenced the rate or profile of metabolites from cellular metabolism of T or DHT. We propose that cultured human genital skin fibroblasts may serve as a valuable system for the future evaluation of antiandrogens in intact ells under physiologic conditions.

New therapeutic approach to the hirsute patient

Spironolactone, an aldosterone antagonist currently used in the treatment of hypertension, has numerous antiandrogenic side effects. Decreased production rates of testosterone in intact (N = 10) and hirsute (N = 6) women, respectively, were noted after short (7 days) or long-term (6 months) administration of the drug, 25 mg twice daily. A 50% diminution in the urinary 17-ketosteroid excretion was also observed after 6 months of therapy. Assessment of the treatment was done by the patients: a reduction in hair growth rate was initially observed after 3 to 4 months, followed by the appearance of a more downy type of new growth and a decrease in diameter of the hair shaft. It is concluded that this beneficial effect is obtained by a decrease in the testosterone production rate and probably through competitive inhibition of spironolactone and/or canrenone with the androgen receptor in human hair follicles.

Increased serum oestrone and oestradiol following spironolactone administration in hypertensive men

The present study was undertaken to evaluate long-term effects of spironolactone on basal serum oestrone, oestradiol, testosterone, LH and prolactin concentrations in hypertensive male patients. Serum prolactin response to TRH was also evaluated. Patients were divided into two groups: a conventional-dosage group, consisting of six males with essential hypertension who took 75 to 150 mg of spironolactone daily for 12 weeks, and a high-dosage group, consisting of two males with idiopathic hyperaldosteronism who took 300 mg of spironolactone daily for more than 40 weeks. In the conventional-dosage group, serum oestrone concentrations significantly increased (P less than 0.01) at 12 weeks, serum oestradiol concentrations gradually increased throughout the study period, however, the increments were not statistically significant (P less than 0.2). Basal serum testosterone, LH and prolactin concentrations were not significantly changed throughout the study period. Enhancement of serum prolactin response to TRH was not found in any of the patients in the conventional-dosage group. In the high-dosage group, serum oestrone maintained high levels from the beginning of this study, and serum oestradiol concentrations increased with the development of gynaecomastia. Serum testosterone, LH and prolactin concentrations did not show any definite change throughout the study period. Thus, long-term spironolactone treatment increased the serum levels of oestrone and oestradiol in hypertensive men followed by the development of gynaecomastia. The elevation in circulating oestrogens could well explain the oestrogenic side-effects of spironolactone treatment.

Assay of androgen binding sites by exchange with methyltrienolone (R 1881)

Methyltrienolone (R 1881 - 17beta-hydroxy-17alpha-methyl-estra-4,9,11-trien-3-one) binds specifically to androgen receptor in rat prostate cytosol where, unlike androstanolone, it is not metabolized. By exchanging bound endogenous hormone in rat prostate cytosol with labelled R 1881, it is possible to measure total (free anc occupied) binding sites. This assay method has also been applied to the measurement of androgen receptor sites in human benign prostatic hypertrophy where R 1881 has the added advantage of not being bound by any contaminating plasma protein (sex hormone binding protein).

Androgens

Testosterone is synthesised mainly if not entirely by the leydig cells and secreted episodically with a slight circadian variation. Only the free, nonprotein-bound fraction of the testosterone in the circulation is biologically active. This free testosterone passes into the target cells and is taken up by specific receptors in the muscle. In some other target tissues, testosterone is first reduced to 5alpha-dihydrotestosterone which is then taken up by specific receptors in the cytoplasm and transferred to the nucleus. Anti-androgens appear to act principally by inhibiting this uptake.