What is Levodopa used for?

Levodopa is an amino acid derivative present in nature. It is mainly found in legume plants, especially Levodopa with higher concentrations in prickly beans.

Levodopa has the dual structural properties of amino acids and catechol. The catechol structure makes it easy to oxidize and complex with metal ions. Decarboxylation reactions are prone to occur in vivo and in vitro to produce dopamine.

Its appearance is usually white or white-like crystalline powder. Slightly soluble in water and almost insoluble in ethanol, chloroform or diethyl ether. It is easy to oxidize and discolor in the air, and the aqueous solution is easy to oxidize and decompose. Therefore, it is necessary to block and store light and seal.

Although Levodopa exists from plants, its extraction cost is high, low efficiency is limited by seasonal and planting conditions. Therefore, the Levodopa required by the modern pharmaceutical industry mainly relies on chemical synthesis and biotechnological methods to meet market demand.

Levodopa is currently the most effective and core drug to improve the motor symptoms of Parkinson's Disease (PD). Its efficacy is mainly reflected in the reversal of Parkinson's disease's most important motor dysfunction.

Levodopa enters the central nervous system through the blood-brain barrier and converts it into dopamine in the brain. Dopamine itself cannot penetrate the blood-brain barrier and enters the central nervous system. As an amino acid derivative, Levodopa can actively transport through the blood-brain barrier through the brain's amino acid transport system, directly supplementing the severely lacking dopamine in the substantia nigra striatum. The newly generated dopamine is released into the synaptic cleft and acts on the dopamine receptors in the postsynaptic membrane. Therefore, the recovery of dopamine levels allows the "direct pathway" and "indirect pathways" that are imbalanced due to dopamine deficiency in the basal ganglia to be rebalanced, thereby improving the normal function of the cortico-basal ganglia-thalamus-cortical motor circuit and ultimately improving motor control.

Oral Levodopa will improve the patient's movements to become smoother, faster and more magnified.

For example: After taking Levodopa products, it becomes easier and faster to get up, turn over, and walk, and the movements can also be refined (tied shoelaces). Please follow the doctor's instructions to take the dosage.

The patient appears in the middle and late stages, which are manifested as forward leaning, unstable gait, small steps, panic gait, and easy to fall. After taking related products, the gait is more stable, the stride is larger, the pace is more coordinated, the body leans forward less, the difficulty in turning is improved, and the balance ability is improved. However, improvements to postural balance disorders are usually less significant and lasting than the first three symptoms, especially in the late stages of the disease. Please follow the doctor's advice for the dosage.

Note: Do not take single-ingredient dopamine orally to treat Parkinson's disease. The core of oral treatment of Parkinson's disease is the Levodopa compound preparation. There is no fixed standard for the specific dosage, and the doctor's instructions must be strictly followed. At the same time, regular follow-up visits and close communication with doctors on symptom changes and drug response are the key to ensuring safe and effective treatment.

1. Common side effects

Gastrointestinal discomfort, nausea, vomiting, loss of appetite, abdominal pain, diarrhea, etc.

If nausea and vomiting occur, it may be caused by dopamine stimulation of the trigger area of the medulla chemoreceptor. It can be gradually tolerated as the medication is used for a longer period of time, or it can be relieved by taking medicine after meals and adding domperidone. For specific treatment, you can seek medical treatment directly.

2. Long-term side effects

Includes central motor complications and central nervous system complications.

If central motor complications are encountered, the effective time of each drug will gradually shorten, accompanied by periodic fluctuations in motor symptoms (tremor, stiffness, slowness) and non-motor symptoms (anxiety, abnormal sweating). Before the next medication (usually 1-2 hours in advance), the symptoms recur or worsen (such as stiffness, slowness, tremor), and the frequency of medication needs to be increased, switch to sustained-release dosage form, add COMT inhibitor (entacapone) or MAO-B inhibitor to prolong the action time of levodopa.

Secondly, it will appear, and it will be free to move at the beginning, which may be accompanied by dysfunction. Later, there will be unpredictable and violent fluctuations between the "sudden stiffness, inability to move" periods. As well as abnormal motor symptoms such as involuntary, dance-like or dystonia. These symptoms are related to fluctuations in drug concentration and receptor hypersensitivity. I believe that you need to follow the doctor's advice, let the doctor make a judgment and give improvement methods.

1 International Parkinson and Movement Disorder Society Evidence-Based Medicine Review: Update on Treatments for Motor Symptoms of Parkinson's Disease

2.European Academy of Neurology/Movement Disorder Society-European Section Guideline on the Treatment of Parkinson's Disease

3. Levodopa-induced dyskinesia in Parkinson's disease: pathogenesis and emerging therapies

4.Management of Psychosis in Parkinson's Disease: Emphasizing Clinical Subtypes and Pathophysiological Mechanisms of the Disorder

5.Impulse control disorders in Parkinson's disease: A systematic review on risk factors and pathophysiology