Levodopa is called the "gold standard" in Parkinson's treatment. Despite the introduction of more modern preparations to the market, it still remains the basic and most important drug in the treatment of this disease. However, its use raises many concerns in patients related to side effects. Are they right? How does levodopa work?

Levodopa , introduced to the pharmaceutical market in the 1970s, turned out to be a breakthrough in the treatment of Parkinson's disease. This drug changed for the better and extended the lives of millions of people around the world. His discovery won the Nobel Prize for Arvid Carlsson in 2000. To date, no drug has been found that would show greater potency in Parkinson's therapy.

The introduction of levodopa statistically significantly extended the life of patients. As a result, after its introduction, new and more advanced Parkinson's symptoms appeared. This is because this disease is characterized by a constant progression of development. Along with the longer life, the Parkinson's process extended and the next phases of this disease revealed themselves.

Parkinson's is a neurological disease that causes permanent damage to the brain. Modern medicine is not able to undo these changes, it can only modify their course.

Parkinson's disease causes the degeneration of the structures of the brain. During it, nerve cells in the substantia nigra die. These cells are responsible for the production of dopamine. This leads to a decrease in the concentration of this neurotransmitter in some areas of the brain important for the control of movement.

Levodopa - mechanism of action

Levodopa is chemically an amino acid precursor to dopamine. In the body, after crossing the blood-brain barrier, it is transformed into the mentioned neurotransmitter. As a result, the concentration of dopamine in the appropriate brain structures increases.

Levodopa and the symptoms and course of parkinson's

We still don't know the cause of the disease. This makes it difficult to find the perfect Parkinson's drug. Levodopa in combination with accompanying preparations is considered the most effective option available today.

Research shows that a predisposition to Parkinson's is genetically transmitted to some extent. Environmental factors that cause damage to the nervous system are likely to be responsible for the development of the disease in susceptible individuals.

The main and most important symptom of this disease is slowing down of movements. It is visible in patients as problems withcommencement of a motor activity and its acceleration. As a result, patients have difficulty speaking, walking and everyday basic activities.

Another common symptom is muscle stiffness. It can be perceived by the patient as pain while moving. Muscle stiffness can also be seen in facial expressions. As a result, patients often have a characteristic "masked" face.

Parkinson's is also associated with disorders of body posture specific to this disease. They are caused by problems with keeping the balance. Patients often interpret it as "dizziness". Movement instability is dangerous due to the high risk of falls which lead to serious injuries.

Initially, doctors believed that Parkinson's disease manifested itself only through movement disorders. After introducing the therapy with the first highly effective drug, i.e. levodopa, it turned out to be a much more complex disease with a wide range of symptoms. Parkinson's is responsible for the development of dementia as well as psychotic disorders. It can be said that these symptoms are due to the fact that mental functions also slow down.

Treatment options for Parkinson's disease

Since we do not know the cause of Parkinson's, there are no causal drugs for this disease. The possible therapy methods are:

  • administering disease-modifying drugs
  • use of relieving medications

Non-pharmacological treatments are also possible:

  • surgical treatment involving deep brain stimulation
  • rehabilitation
  • gene therapy

Pharmacological treatment usually uses levodopa in combination with other medications, such as:

  • catechol methyltransferase (COMT) inhibitors
  • dopamine agonists: bromryptine, pergolide, cabergoline, pramipexole, ropinirole, piribedil, apomorphine, rotigotine
  • cholinolytic drugs: trihesyphenidyl, biperiden
  • MAO inhibitors: selegiline, rasagiline
  • amantadine

MAO and COMT inhibitors are used to extend the activity of levodopa and increase its bioavailability in the body. Both groups block the breakdown of the drug by enzymes. As a result, more of the active substance reaches the brain.

Cholinolytic drugs and amantadine are used to relieve symptoms such as body tremors.

Levodopa as a symptomatic drug

Levodopa has a short-term effect of reducing the motor symptoms of Parkinson's. The therapeutic effect comes shortly afterusing the dose. It exhibits the strongest symptomatic effect of all medications available for use in this disease. Levodopa works very quickly, but the strong effect only lasts for a few hours. High-severity side effects are associated with the short-term effect.

The long-term effects of levodopa last from several days to weeks after taking it. This effect is significantly weaker than the short-term effect, however, it is stable and lasts for a long period of time. Low intensity side effects are associated with long-term effects.

A combined preparation containing levodopa is available in Poland:

  • levodopa + benserazide
  • levodopa + carbidopa

Levodopa and Parkinson's Progress

Parkinson's disease is progressive. Despite the appropriate treatment, the patient's condition will continue to deteriorate. Properly selected drugs, however, can significantly extend life and increase its quality.

The first period of the disease development is sometimes called the "honeymoon". It usually takes 5 years. It has a very good response to levodopa. The medications used eliminate the symptoms of the disease. The doses used are low, which reduces side effects.

As the disease progresses, there is an increasing loss of nerve cells. The brain damage is increasing. With these changes, response to drugs decreases. It is necessary to constantly increase the dose of the drug. There are also new problems with the response to the drug called fluctuations.

Immediately after the patient uses the drug, there is an improvement. Unfortunately, it lasts for a short time, about 3 hours. After this time, body stiffness, tremors and slowness appear. These symptoms only disappear with the next dose. The state of the sick person is called "off".

As the disease progresses, response to medications is delayed. In the early stages of Parkinson's, levodopa works almost immediately after you take it. Later in development, it takes 30 minutes or even an hour to improve. Patients often feel that their medication has stopped working. This phenomenon is called delayed on.
With the need to increase the levodopa dose, there is a problem of increasing side effects. The "on" phase appears. At the time of the peak dose, which is the highest concentration of the drug in the brain, involuntary chorea movements occur. These movements are called dyskinesias.

All these problems associated with a worsened response to drugs make daily life difficult for the patient. As a result, falls often occur, which can lead to serious injuries. OnHowever, at this stage of development, the patient is usually relatively independent.

In the most severe phase of the disease, the response to levodopa is negligible. The walking disturbances worsen gradually, until the patient spends most of the time in bed or in a wheelchair.

Levodopa - the dilemma of the first dose

The issue of introducing levodopa into therapy immediately after diagnosis is still debatable. The most common solution is to start treatment with the smallest dose that brings a therapeutic effect.

Another popular solution is to start treatment with dopamine agonists. In such a regimen of therapy, levodopa is introduced only in the later stages of the disease.

As previously mentioned, the mechanism of the onset and development of Parkinson's disease is poorly understood. As a result, there are still debates about the best possible treatment regimen. There are supporters of deferring the use of levodopa, as well as specialists who believe that the best solution is to start therapy with doses of high activity.

Levodopa - side effects

A serious complication that sometimes occurs with levodopa therapy is dopaminergic dysregulation syndrome. It manifests itself with euphoria and involuntary movements. Occasionally, hallucinations and hyper-arousal appear. It usually results from too high a concentration of the drug in the body.

It happens that patients increase the dose on their own without consulting a doctor, because they have the impression that the current one has stopped working. Unfortunately, this is a straightforward pathway to dopaminergic dysregulation syndrome.

The most common side effects of levodopa include:

  • nausea
  • vomiting
  • sleepiness
  • mood changes
  • red urine
  • anxiety
  • hallucinations
  • movement disorders - sudden involuntary movements of the limbs and head
  • sensory disturbance
  • cardiovascular disorders

What should I remember when taking levodopa?

Levodopa should be taken 30 minutes before or at least one hour after a meal. This is because food reduces the absorption of this drug. A low-protein diet is also recommended because the amino acids contained in it compete with levodopa during absorption, which reduces its bioavailability.

The exception is the situation in which the patient vomits after administration of the drug, which prevents the proper administration of the drug. It is then recommended to take a tablet or capsule with a meal in order to reduce the side effects of the gastrointestinal tract.

Extremely important in levodopa therapyis to take doses regularly at certain times. This ensures therapeutic effectiveness and reduces side effects.

Patients who start treatment must be prepared for the fact that selecting the right dose of the drug may take some time. For the therapy to be effective, frequent consultations with the doctor are necessary. The first approach to the drug can be daunting, but don't give up. Using the right dose of levodopa in combination with other drugs is the most effective therapy model available today.

Levodopa treatment should never be stopped suddenly on your own. Any doubts about lack of effectiveness or side effects should be discussed with your doctor.

Levodopa - contraindications

Levodopa is a drug contraindicated in people with schizophrenia. It also has an adverse effect on the course of glaucoma.

Interactions of levodopa with other drugs

  • reseprine and neuroleptics may weaken the effects of levodopa
  • drugs for high blood pressure in combination with levodopa can cause hypotension
  • vitamin B6 inhibits the action of levodopa
About the authorSara Janowska, MA in pharmacyPhD student of interdisciplinary doctoral studies in the field of pharmaceutical and biomedical sciences at the Medical University of Lublin and the Institute of Biotechnology in Białystok. A graduate of pharmaceutical studies at the Medical University of Lublin with a specialization in Plant Medicine. She obtained a master's degree defending a thesis in the field of pharmaceutical botany on the antioxidant properties of extracts obtained from twenty species of mosses. Currently, in his research work, he deals with the synthesis of new anti-cancer substances and the study of their properties on cancer cell lines. For two years she worked as a master of pharmacy in an open pharmacy.

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