Active Ingredients

Benserazide – Effect, Application & Risks


Benserazide is an active ingredient that is not available as a mono-preparation, but is always administered in combination with levodopa . Both active substances are prescribed exclusively for the treatment of Parkinson’s and Restless Legs Syndrome . Benserazide supports the prodrug levodopa so effectively because it acts directly on the periphery.

What is benserazide

Benserazide (chemical formula: C10H15N3O5) occurs as benserazide hydrochloride only together with levodopa. It is a white to yellowish, crystalline, non-water-soluble powder. It belongs to the group of benserazide decarboxylase inhibitors. As the name suggests, it blocks the action of dopamine decarboxylase, an enzyme that breaks down the neurotransmitter dopamine in the blood and gut .

Benserazide cannot cross the blood-brain barrier and only acts peripherally (i.e. outside the central nervous system ). It prevents L-dopa breakdown at the periphery and thus ensures that the dopamine precursor can pass the blood-brain barrier and produce the much-needed dopamine in the brain .

In the tablets to be taken orally against Parkinson’s disease and Restless Legs Syndrome, both active substances are present in a ratio of 4:1 (L-dopa:benserazide). They are sold under the trade names Madopar®, Levopar® and Levodopa comp.® and contain dosages of 100 mg/25 mg, 200 mg/50 mg and 50 mg/12.5 mg.

Pharmacological action

Together with levodopa, benserazide helps to alleviate the symptoms typical of Parkinson’s disease, namely shaking (tremor), muscle rigidity ( rigor ) and disturbed movements (akinesia), to give the affected person more freedom of movement and to slow down the progression of the disease.Since the neurotransmitter dopamine, which effectively reduces these symptoms, cannot cross the blood-brain barrier itself, it is administered in the form of its precursor (L-dopa). In turn, most of this drug is broken down in the body by an enzyme called dopamine decarboxylase before it can get to where it is needed to make more dopamine (the brain). Since the patient would have to be administered too high a dose of L-Dopa for any of the active substance to reach the brain at all, it is administered together with benserazide.

Benserazide hydrochloride inhibits the activity of the L-dopa-degrading enzyme very effectively, since it can bind to the enzyme and deactivate its catalytic center due to its molecular similarity to levodopa. L-Dopa is thus able to cross the blood-brain barrier unhindered and in full dose.

Another pharmacological effect of benserazide is that it prevents prolactin secretion in breastfeeding women . This hormone is responsible for the production of breast milk .

Medical Application & Use

The combination drug levodopa + benserazide is indicated for long-term therapy in patients with Parkinson’s disease and restless legs syndrome. In addition, it is used in people who show Parkinson’s-like symptoms, although these must not be a side effect of an administered drug.

Parkinson’s patients regain at least some of their mobility thanks to the active ingredients. In addition, the rapid progression of the disease is inhibited. In Restless Legs Syndrome, which apparently also goes back to a lack of dopamine in the brain, the symptoms that occur in bed at night (uncontrollable urge to move, sudden pain and muscle twitching ) are alleviated. The patients find nocturnal rest.

In addition, the drug combination levodopa + benserazide is used to diagnose “restless leg syndrome”: If the symptoms are noticeably alleviated, the person affected is actually suffering from this disease. For this purpose, the doctor usually administers the preparation in the form of tablets of 100 mg/25 mg. The combination drug can also be easily combined with other approved drugs for Parkinson’s disease.

Risks & side effects

When taking levodopa + benserazide, the following side effects occur very often in the case of Parkinson’s disease: Loss of movement control over the mouth, tongue and head, disturbed body movements , urine discoloration, nausea and vomiting . Frequently observed are anxiety , depression , restlessness, confusion , drowsiness , insomnia , loss of appetite , sweating , tremors , fatigue , indigestion , dry mouth andabdominal pain .Restless Legs Syndrome patients who have been prescribed the drug very often have sleep disorders, depression, diarrhea , nausea and vomiting. Altered taste buds , hallucinations , anxiety and cardiac arrhythmias are common.

Levodopa + benserazide should not be used if the patient has hypersensitivity to the active ingredients, a pheochromocytoma (adrenal tumor), severe hyperthyroidism , psychosis , tachycardia , angle-closure glaucoma , severe liver , heart , kidney , metabolic and bone marrow disease has or is under 25 years old.

It should also not be used during pregnancy . Embryonic damage occurred in animal experiments. No medical data are available for humans. Breastfeeding women should definitely stop breastfeeding if they have to take the drug.

It is given to people with a history of peptic ulcer disease , myocardial infarction , coronary artery disease , cardiac arrhythmias , open-angle glaucoma , bone softening , and diabetes only when there is an urgent medical indication. You will be regularly checked by a doctor during treatment.

If the active ingredient combination against Parkinson’s disease and Restless Legs Syndrome is administered together with painkillers (opiates), neuroleptics , iron preparations, acid-binding drugs ( antacids ), phenytoin , papaverine , antihypertensive and circulatory-supporting drugs, its effect is reduced.

The effect of levodopa + benserazide is enhanced when the drug is taken with selective MAO-B inhibitors. For example, the dose of amantadine or selegeline may need to be adjusted. MAO-A inhibitors should be discontinued 14 days before taking levodopa + benserazide, otherwise the patient may experience a critical rise in blood pressure . The stomach drug metoclopramide ensures faster absorption of the active substances and more side effects.

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.