Parkinson’s disease is a progressive neurological disorder that primarily affects movement.
It is more common among older adults, although younger individuals can also develop the condition.
The exact cause remains unknown, but it is believed to involve a combination of genetic and environmental factors.
The symptoms of Parkinson’s disease develop gradually and vary from person to person.
The most recognisable motor symptoms include shaking or tremors, muscle stiffness or rigidity, and slowness of movement, known as bradykinesia.
These symptoms may make everyday activities such as walking, dressing, eating and writing increasingly difficult.
Beyond movement difficulties, Parkinson’s disease may also cause non-motor symptoms, some of which can appear before physical changes become noticeable.
These include fatigue, depression, anxiety, slowed thinking and poor concentration.
Some individuals may also experience pain, tingling, constipation, dizziness upon standing, urinary difficulties, excessive sweating and sleep disturbances.
Parkinson’s disease develops when dopamine-producing nerve cells in the brain gradually deteriorate.
Dopamine is a chemical messenger that helps the brain coordinate smooth and controlled movement.
As dopamine levels decrease, movement may become slower and more difficult, while stiffness and tremors may become more noticeable.
Although Parkinson’s disease has no cure, appropriate treatment can help control its symptoms, support daily functioning and improve quality of life.
Medicines remain an important part of treatment because they can replace dopamine, imitate its effects or help dopamine remain active in the brain for longer.
Levodopa
Levodopa remains the most effective treatment for managing the motor symptoms of Parkinson’s disease.
Since dopamine itself cannot easily cross the blood-brain barrier, direct supplementation is ineffective.
Levodopa is a precursor molecule to dopamine, allowing nerve cells to convert it into dopamine once it reaches the brain.
However, a large portion of levodopa may be broken down before it reaches the brain.
To prevent this, levodopa is combined with a medicine such as carbidopa or benserazide.
This allows more levodopa to reach the brain and helps reduce certain unwanted effects.
Levodopa can improve slowness of movement and muscle stiffness, and may reduce tremors in some patients.
However, the response to treatment varies between individuals.
The dose and timing may therefore need to be adjusted according to the patient’s symptoms, daily routine and response to treatment.
Over time, some patients may notice that the effects of each levodopa dose do not last as long as before.
They may experience “on” periods, when symptoms are well controlled, and “off” periods, when symptoms return before the next dose.
Some patients may also develop dyskinesia, which are involuntary movements that are distinct from the tremors due to Parkinson’s.
These complications are particularly common in younger patients and those taking higher doses over extended periods.
However, they do not necessarily mean that levodopa is no longer effective or suitable.
Patients should pay attention to when the symptoms occur and discuss them with their doctor or pharmacist, as adjustments to the dose or frequency of levodopa may help improve symptom control.
Importantly, the medicine should never be stopped abruptly without medical supervision.
Other medicines
In addition to levodopa, other medicines may be used to manage the symptoms of Parkinson’s disease.
They may be prescribed alone or together with levodopa, depending on the patient’s symptoms and response to treatment.
The medicines are:
These medicines mimic dopamine by stimulating dopamine receptors in the brain.
Common examples include pramipexole, ropinirole and piribedil.
They are less likely to cause motor fluctuations during the early stages of the disease, although they may be less effective than levodopa in controlling symptoms.
Medicines such as selegiline block MAO-B, an enzyme that breaks down dopamine.
By slowing dopamine degradation, these medicines help prolong the effects of dopamine and may also enhance the effects of levodopa.
Potential side effects include nausea, insomnia and low blood pressure.
COMT inhibitors such as entacapone, reduce the breakdown of levodopa, thereby extending its effects and reducing “off” periods.
Possible side effects include nausea, dizziness and sleep disturbances.
Patients taking entacapone may notice a harmless brownish-orange discolouration of the urine.
Medicine such as benzhexol helps to control Parkinson’s-related tremors by reducing acetylcholine activity.
However, they may cause dry mouth, dry eyes, urinary retention, constipation and confusion, making them less suitable for older patients.
Originally developed as an antiviral medicine, amantadine may help alleviate Parkinson’s symptoms and reduce levodopa- induced dyskinesia.
Side effects may include insomnia, leg swelling, confusion and hallucinations.
Advice for patients and caregivers
Medicines should be taken at the prescribed dose and time to maintain consistent symptom control.
Patients should not adjust the dose, change the timing or stop their medicines without advice from a doctor or pharmacist.
This is as sudden changes may cause symptoms to worsen.
Any new or worsening side effects, such as involuntary movements, dizziness, excessive sleepiness, hallucinations or changes in behaviour, should also be discussed with healthcare professionals.
Patients should inform the doctor or pharmacist about all medicines, traditional products and supplements they are taking, including those obtained from different healthcare facilities or purchased on their own.
Caregivers can assist by helping patients follow their medicine schedule and observing changes in symptoms, daily functioning or behaviour that patients may not notice themselves.
Patients and caregivers should also consider supportive care such as physiotherapy, occupational therapy, speech therapy, suitable physical activity and nutritional support.
These approaches may help patients maintain mobility, independence and communication.
Family members and caregivers can provide emotional reassurance, practical assistance and encouragement for patients to remain involved in daily activities.
Such support can help patients cope with the physical and emotional challenges of Parkinson’s disease and maintain their quality of life.
Living well with Parkinson’s
Parkinson’s disease affects each person differently, and its treatment may change as the condition progresses.
A suitable combination of medicines and supportive care can help control symptoms and preserve independence in daily life.
Although treatment cannot cure Parkinson’s disease, a clear understanding of the medicines used and close communication with healthcare professionals can help patients and caregivers make informed decisions throughout the course of treatment.
With appropriate care and support, people with Parkinson’s disease can continue to live meaningful and fulfilling lives.
For any inquiries about medicines, please call the National Pharmacy Call Centre (NPCC) at the toll-free number 1-800-88-6722 during weekdays from 8am to 5pm, except on public holidays.
Thor Xiao Xuan is a pharmacist at Hospital Balik Pulau in Penang. This article is courtesy of the Health Ministry’s Pharmacy Practice and Development Division. For more information, email starhealth@thestar.com.my. The information provided is for educational and communication purposes only, and should not be considered as medical advice. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this article. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
