Bicalutamide

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 bicalutamide is a so-called non-steroidal anti-androgen and is used to treat prostate cancer. In the past, it was only approved in combination with other forms of therapy, but it is now also used as a sole therapy (especially in the early stages). Here you can read everything you need to know about the effects and use of bicalutamide, side effects and other important facts.

This is how bicalutamide works

The prostate (prostate gland) is a sex gland that is only found in male mammals and secretes a secretion that is part of the sperm. It lies under the bladder and encloses the urethra. The growth of the prostate is controlled by the male sex hormones (androgens) testosterone and dihydrotestosterone (a derivative of testosterone).

Random mutations (genetic changes) in the genome of the prostate cells can begin to multiply in an uncontrolled manner - this is called prostate cancer. Its growth depends on the supply of testosterone and dihydrotestosterone, which is why therapy attempts to block the docking points (receptors) of these hormones on the prostate cells. This is done with the help of so-called "antiandrogens" such as bicalutamide.

In the early stages of the disease, therapy with bicalutamide alone can stop the tumor from growing. In advanced stages, an additional measure (surgical removal of the prostate, radiation therapy, hormone therapy, chemotherapy) is often taken.

Uptake, breakdown and excretion of bicalutamide

After ingestion through the mouth, the active ingredient is well absorbed through the intestines into the blood. It is broken down in the liver in various ways and about half of it is excreted in the stool and half in the urine. Excretion is very slow, after a week only about half of the active ingredient is removed from the body.

When is bicalutamide used?

The active ingredient bicalutamide is approved for the sole or combined treatment of prostate cancer.

Scientific studies have shown that the active ingredient in low doses can also be used successfully against unwanted hair growth (hirsutism) in women. However, taking it for this purpose is outside the approval (so-called "off-label use").

This is how bicalutamide is used

The active ingredient is only available in the form of tablets. Depending on the type of therapy, 50 milligrams or 150 milligrams of bicalutamide are taken once a day at the same time of day and regardless of meals. The treatment takes place over a long period of time.

What are the side effects of bicalutamide?

More than ten percent of patients treated with bicalutamide show adverse drug effects in the form of tightness in the chest, breast growth, weakness, water retention in the subcutaneous tissue, dizziness, abdominal pain, constipation, nausea, rash, anemia, hot flashes and blood in the urine.

In addition, one in ten to one hundred people treated with bicalutamide experience side effects such as erectile dysfunction, pelvic pain, chills, drowsiness, liver dysfunction, sweating, increased hair growth, hair loss, itching, diabetes, weight gain and loss, heart failure and heart attacks.

What should be considered when taking bicalutamide?

There are no known interactions with the active substances usually used in combination therapy for the treatment of prostate cancer (such as LHRH analogues).

Since bicalutamide is extensively metabolized in the liver, it blocks enzymes there that also break down other active ingredients, which can greatly increase their blood levels. Therefore, bicalutamide should not be taken together with agents against allergies (such as terfenadine, astemizole), immune system-suppressing agents (such as ciclosporin) and calcium antagonists (such as nifedipine, verapamil, diltiazem; for example in heart diseases).

Conversely, other active ingredients can inhibit the breakdown of bicalutamide, causing it to accumulate in the body. This applies to medicines for fungal infections (such as ketoconazole) and medicines for heartburn (such as cimetidine).

In patients taking anticoagulant drugs (such as warfarin and phenprocoumon), coagulation should be monitored when starting therapy with bicalutamide, as the coagulation values ​​may change.

Because bicalutamide has a massive influence on the hormonal balance of the body, it must not be taken by pregnant or breastfeeding women, children and adolescents under 18 years of age.

In severe liver dysfunction, blood levels of bicalutamide should be monitored.

How to get medication with bicalutamide

In Germany, all preparations with the active ingredient bicalutamide are only available in pharmacies with a doctor's prescription.

How long has bicalutamide been known?

Non-steroidal antiandrogens were first discovered in the 1970s. The first active ingredient in this group of substances, flutamide, was approved in the USA in 1989. However, it was noticed early on that flutamide is broken down comparatively quickly and that the liver is very stressful. With its successor, bicalutamide, an active ingredient was approved in the USA in 1995 that has a much longer duration of action and also better liver tolerance. Since the patent protection has now expired, there are numerous inexpensive generics with the active ingredient bicalutamide on the market.

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