Spironolactone

Benjamin Clanner-Engelshofen is a freelance writer in the medical department. He studied biochemistry and pharmacy in Munich and Cambridge / Boston (USA) and noticed early on that he particularly enjoyed the interface between medicine and science. That is why he went on to study human medicine.

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The active ingredient spironolactone is a drug used to treat high blood pressure (antihypertensive) and a dehydrating agent (diuretic). Spironolactone is called a so-called potassium-sparing diuretic because, in contrast to other diuretics (such as furosemide or hydrochlorothiazide), hardly any potassium is excreted. Here you can read everything you need to know about spironolactone, side effects and use.

This is how spironolactone works

With the help of the kidneys, the body filters the blood and cleans it of waste products, pollutants and also some drugs. The kidney consists of numerous nephrons - the smallest functional units, which in turn each consist of a kidney corpuscle and a kidney tubule. The blood is filtered through the kidney corpuscles, with larger components such as proteins or whole blood cells being retained and smaller substances such as waste products, but also salts and sugar being filtered off. The filtrate obtained in this way is called primary urine; about 180 to 200 liters of it are produced daily. This is still unfocused and is concentrated via the passage through the kidney tubules. Here, salts and sugars that the body can still use are reabsorbed into the blood (they also pull water with them). Substances to be eliminated, on the other hand, can pass freely; this second filtrate leaves the body as secondary or terminal urine.

The active ingredient spironolactone prevents the hormone aldosterone from binding to docking points in the cells of the kidney tubules. As a result, less sodium and water from the primary urine are reabsorbed into the blood, which means that more terminal urine is produced and excreted.The increased fluid excretion also lowers blood pressure.

Breakdown and excretion of spironolactone

After ingestion, roughly three quarters of spironolactone is quickly absorbed from the intestine into the blood. Most of it is then converted in the liver to another form of action called canrenone. The maximum blood levels of spironolactone are reached about one hour after ingestion, those of the metabolic products after about two to three hours. The diuretic effect does not occur immediately, but only after a few days. The maximum effect is reached after about five days. The active ingredient is mainly excreted via the kidneys with the urine.

When is spironolactone used?

The active ingredient spironolactone is approved for the treatment of water retention (edema) and excessively high aldosterone blood levels, which can be clinically expressed as high blood pressure and low potassium levels in the blood. The active ingredient is usually used long-term.

This is how spironolactone is used

Spironolactone is usually taken in the form of tablets or capsules. The dosage must always be determined individually by the doctor depending on the severity of the disease. As a rule, treatment is started with 100 to 200 milligrams of spironolactone per day; If the effectiveness is insufficient, this dosage can be increased to up to 400 milligrams of active ingredient per day. It must always be taken into account that the full effect of spironolactone only occurs after a few days.

Combination preparations with other diuretics are also available on the market.

What are the side effects of spironolactone?

In every tenth to hundredth person treated, spironolactone side effects such as high blood potassium levels, muscle paralysis, high blood uric acid levels with an increased risk of gout attacks, cardiac arrhythmias, sensitivity to touch on the chest and nipples, and breast growth in men (occurs after stopping of the active ingredient back).

In every hundredth to one thousandth patient, spironolactone leads to a reduction in the number of blood platelets, increased urea and creatinine levels in the blood, states of confusion, headache, drowsiness, feeling weak, dizziness, dry mouth, gastrointestinal complaints, ulcers in the gastrointestinal tract, Skin redness, itching, rash, muscle cramps and erectile dysfunction.

What should be considered when taking spironolactone?

The increase in blood potassium levels caused by spironolactone can increase if other active ingredients with a potassium-increasing effect are taken at the same time. This applies, for example, to potassium supplements, certain antihypertensive drugs from the group of ACE inhibitors (captopril, enalapril) and sartans (candesartan, valsartan) and other potassium-sparing diuretics (triamterene, amiloride). Non-steroidal anti-inflammatory drugs (ASA, indomethacin), which are often taken as pain relievers, can also lead to increased potassium levels. In addition, like epilepsy drugs (anti-epileptic) phenytoin, they can weaken the effect of spironolactone.

Taking spironolactone in combination with furosemide and an ACE inhibitor can lead to acute kidney failure and a massive drop in blood pressure. Before starting treatment with ACE inhibitors, the diuretics should be discontinued for a few days so that the initial drop in blood pressure is not too great.

The intake of spironolactone together with the cardiac glycosides digoxin and digitoxin must be strictly monitored by a doctor: it can lead to increased blood levels of the cardiac glycosides. Even a slight increase can result in serious side effects (cardiac glycosides have a so-called narrow therapeutic range).

Spironolactone must not be used during pregnancy and breastfeeding as there is insufficient data on this. It crosses the placental barrier and passes into breast milk.

The active ingredient spironolactone can be used in children and adolescents in a reduced dose according to their body weight.

Patients with severe kidney problems should not take spironolactone as it can further impair kidney function.

How to get medication with spironolactone

Medicines with the active ingredient spironolactone can only be obtained from pharmacies with a doctor's prescription.

How long has spironolactone been known?

Before the introduction of spironolactone, all diuretics resulted in increased excretion of potassium. Although a potassium deficiency can be counteracted by adding potassium, alternatives have been sought. In 1959 the active ingredient spironolactone was first tested by the pharmaceutical company G. D. Searle and finally approved in 1961.

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