Active Ingredients

Spironolactone – Effect, Application & Risks


Spironolactone is a so-called competitive antagonist to the receptor for mineralocorticoids. The active ingredient spironolactone belongs to the pharmacological group of diuretics , which have potassium-sparing properties. The drug is on the WHO list as an essential drug.

What is spironolactone?

Spironolactone is a pharmacological agent that is used as a drug to treat various ailments and diseases. It causes increased flushing of water from the body.

Ingestion reduces the effect of the steroid homone aldosterone, which results in reduced sodium excretion . For this reason it is possible that a higher proportion of potassium is retained. Because of the aldosterone an installation in the sodium channel is hindered or completely impossible. As a result of this mechanism, there is an increased excretion of water.

Pharmacological action

The mechanism of action of spironolactone is primarily based on the fact that the substance blocks the aldosterone receptors. As a result, more water and sodium are excreted. At the same time, a larger amount of potassium is retained.

If the drug spironolactone is taken orally, the bioavailability is over 90 percent. The substance is first absorbed in the small intestine . The drug is then metabolized into the active ingredient canrenoate. In the majority of cases, the half-life of the active substance is around 90 minutes.

In principle, however, the full effect of spironolactone only becomes apparent after a few days. Because it is necessary for the active metabolites to accumulate in sufficient quantities. The maximum diuretic effect of the drug occurs after about five days in most cases. It should be noted that the onset of the effect of spironolactone cannot be brought about more quickly even by increasing the dose.

Spironolactone blocks the collecting ducts in the kidneys . The substance aldosterone is therefore no longer able to bind to its receptor. The sodium channels are impeded in their incorporation while at the same time the luminal membrane on the chief cells is blocked. This severely impairs the reabsorption of sodium. One consequence of this is that no water is drawn into the so-called collecting tubes of the kidneys. As a result, no more water gets into the blood .

Instead, there is an increased excretion of sodium and water. Therefore, the amount of blood in the body also decreases. Thus, the heart is relieved, which is why the blood pressure decreases. In addition, accumulations of water in the tissue are flushed out.

The loss of potassium, which is a consequence of numerous diuretics, is compensated by combined therapy with spironolactone. Clinical studies have shown that treatment with the active ingredient spironolactone has a positive effect on the prognosis and chance of survival in chronic heart failure .

Absorption of the substance spironolactone usually proceeds well following oral administration. After an hour, the drug is completely eliminated from the plasma . However, various metabolic products remain. Basically, these metabolites are largely responsible for the effect of the drug.

In principle, the metabolism of the drug is complex. The substance canrenone plays an important role and is found both in the urine and in the blood. Numerous metabolic products of this process are excreted via stool and bile .

Medical Application & Use

The drug spironolactone is used in the majority of cases to treat liver cirrhosis and heart failure. Depending on the individual indication, the attending physician prescribes dosages of 25 to 100 milligrams per day.

In addition, the drug spironolactone is also used with increased concentrations of aldosterone. The underlying diseases are usually liver cirrhosis or primary hyperaldosteronism .

Spironolactone is very effective in chronic heart failure. However, it tends to be rarely used for this purpose in Europe, while it is used as a standard drug in the US.

Spironolactone is also used in endocrinology for people with transsexuality . The drug acts as a testosterone blocker by interfering with the synthesis of the hormone and its binding to the appropriate androgen receptors.

Risks & side effects

As part of therapy with the drug, various undesirable side effects and symptoms are possible, which differ depending on the patient and individual case. The most common cause is an increased level of potassium in the blood. For this reason, patients should be medically monitored while they are taking it.

In addition, with high dosages of the drug, hormonal disorders are possible. These are expressed, for example, in women not having menstrual periods. Male patients may experience erectile dysfunction or voice changes. In the case of transsexual people, precisely these effects are sometimes desired.

Interactions can be seen, for example, when the active ingredient digoxin is taken at the same time . Increased concentrations of the cardiac glycoside in the plasma are possible. Other side effects may include hyperkalemia , gynecomastia , or impotence .

Some side effects of spironolactone lead to the drug being used as a doping agent in sports. It should be noted that misuse of the active substance and an overdose significantly increase the risk of damage to the kidneys.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.