Treatment Of Parkinson’s

Treatment of Parkinson’s is aimed at improving the quality of life of patients.

Treatment for Parkinson’s is usually started as soon as the disease is diagnosed. Depending on the limitations suffered by the patient, concomitant diseases and the medications used to date, a series of measures or others will be chosen.

Therefore, all these measures are intended to help maintain the quality of life of the patient. And prolong its functionality for as long as possible. Ideally, the treatment should avoid surgical intervention; however, this is not 100% guaranteed.

What is Parkinson’s disease?

Parkinson’s disease is a degenerative disorder of the central nervous system (brain and spinal cord). It is characterized by the progressive deterioration of the dopaminergic neurons of the substantia nigra.

The prevalence of the pathology is clearly related to age, being a rare disease before 40 years of age. The annual global incidence is about 5 new cases per 100,000 inhabitants, with a peak incidence between 60 and 70 years.

Parkinson’s disease is the second most common neurodegenerative disorder after Alzheimer’s. It affects 1 in every 250 people over 40 years of age but the ratio is greatly altered in older ages until it affects 1 in 10 people over 80 years of age.

The presence of Lewy bodies in the brain and the reduction of dopamine are characteristic, which is responsible for the appearance of the most representative symptoms:

• Suppression of voluntary movements ( bradykinesia ).
• Tremor of rest.
• Muscular stiffness.
• Certain cognitive impairment.

Parkinson’s treatment

Currently, the pharmacological treatment of Parkinson’s disease seeks to reduce muscle deterioration through physiotherapy and stop motor symptoms when they begin to affect the quality of life of the subject.

For this reason, most of the available treatments are geared toward one of the following goals:

• Restore the dopamine content in the striated substantia nigra.
• Mimic the effects of dopamine in the central nervous system.
• Restore the balance between the dopamine and acetylcholine systems.

Sometimes, due to the digestive difficulties these patients present, it is necessary to resort to parenteral administration systems for some of the drugs. Generally, levodopa is the base drug in the treatment of Parkinson’s.

Levodopa

Levodopa is a precursor of dopamine and, associated with carbidopa or any other inhibitor of peripheral dopa decarboxylase, is the most effective drug for controlling the motor symptoms of the disease.

The association of levodopa with a peripheral dopa decarboxylase inhibitor prevents the transformation of levodopa into dopamine before it reaches the central nervous system.

The two dopa decarboxylase inhibitors available in combination with levodopa are benserazide and carbidopa. This association is effective at any stage of Parkinson’s disease. It improves some symptoms such as stiffness or bradykinesia, although not all patients have a stable response.

After 2 – 5 years of treatment, 80% of patients develop motor complications, response fluctuations ( on-off phenomena ) and involuntary movements that decrease their quality of life.

The use of domperidone in conjunction with levodopa controls gastrointestinal manifestations. On the other hand, it is important to note that the most common side effects of levodopa are:

• Sickness.
• Threw up.
• Hypotension
• Drowsiness.
• Hallucinations

Dopamine agonists

So-called dopamine agonists directly stimulate dopamine receptors found on neurons in the striatum.

The commercially available ergot structure agonists are bromocriptine and cabergoline. Non-ergot drugs are more widely used than the previous ones, highlighting ropirinol, pramipexole, and rotigotine. These drugs should never be withdrawn abruptly as symptoms of apathy and anxiety may appear.

Dopamine agonists produce more side effects than levodopa. Nausea, vomiting, hypotension, and impulse control disorders are notable. The latter make it necessary to reduce or interrupt treatment with these drugs on numerous occasions.

Monoamine oxidase B inhibitors (MAO-B)

Its action in the treatment of Parkinson’s is associated with blocking an enzyme, monoamine oxidase B (MAO-B). Its inhibition results in an increase in dopamine levels, altering the progress of the disease.

The first two drugs in the group were selegiline and rasagiline. Rasagiline is a drug widely used in cases of mild Parkinson’s although its action is also. The latest drug marketed within this category is safinamide, which is an inhibitor 1000 times more selective than the previous ones.

Catechol-O-methyl transferase (COMT) inhibitors

The reference medicine in this group is entacapone. It has been shown to be effective in fluctuating response patients with an efficacy rate similar to that of rasagiline.

Tolcapone was the first drug marketed but at present it is only available as a hospital diagnostic drug (DH). It is not considered one of the first-line drugs. 

Anticholinergics

Anticholinergic drugs were, in fact, the first used for the treatment of Parkinson’s. These restore the balance that exists in the brain between dopamine and acetylcholine in healthy patients. Once introduced into therapy, it is difficult to withdraw them due to the reappearance and even the worsening of the symptoms.

Trihexyphenidyl, biperiden and procyclidine are little used due to the incidence of side effects. Among them are:

• Constipation.
• Blurry vision.
• Urinary retention.
• Dry mouth or feeling thirsty.

Other approaches in the treatment of Parkinson’s

When pharmacological therapies are not enough, other types of approaches can be chosen. Among them we find surgery and electromagnetic stimulation. Gene therapy is still in an experimental phase although it is emerging as a promising option in the treatment of Parkinson’s.