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Commonly Used Drugs

While the treatment for PD is constantly improving, there is no single, optimal treatment because the condition affects each individual differently. The symptoms can usually be effectively controlled, using a combination of therapies, which may include the following:

  • Medication
  • Adjunct therapies, such as physiotherapy, occupational therapy, speech and language therapy
  • Surgical treatments

One needs to work closely with ones doctor to find the right balance of treatments for specific symptoms experienced. Regular reviews are required and adjustments made as symptoms alter.

Commonly Used Drugs in PD

The main aim of drug treatment in Parkinson’s disease is; to increase the level of dopamine that reaches the brain, stimulate the parts of the brain where dopamine works, or block the action of other chemicals that affect dopamine, such as acetylcholine.

Drug treatment in Parkinson’s is prescribed to suit the individual, both in terms of the dosage, the form of the medication (e.g. slow release) and the times the drugs are taken. A combination of different medications is often required to provide the most effective symptom control. You will need to work with your doctor to find the right balance of medications to effectively manage your symptoms.

Treatment is generally started with low doses of a drug; this dose is then gradually increased until the required control over the symptoms is achieved. This gradual introduction helps avoid side effects. Nonetheless, some drugs may have unavoidable side effects. Thus it is important to have a thorough consultation with the doctor so as to be aware of and prepared to cope with the same.

The dose and timing of medications may need to be adjusted over time as your symptoms change (or side effects occur). Accordingly, your doctor will probably want to check your response to the medication.

PLEASE NOTE: No two people with Parkinson’s are exactly the same, and each will have a different combination of symptoms and medication. The drugs mentioned here and some of the information related to them may change from time to time.

A Quick Glance at the drugs/medication available for the management of PD;

Levodopa

Levodopa therapy is a principal medical treatment for the symptoms of Parkinson's disease. It successfully provides relief from the main symptoms of the condition and dramatically enhances the life of people with Parkinson's disease by improving motor function, mobility and enabling participation in everyday activities.

Levodopa is converted to dopamine in the body, which then replenishes the deficiency of dopamine in the brain. Levodopa is usually given as a tablet or capsule.

Levodopa - Carbidopa; like - Syndopa, Sinemet, Tidomet, LCD, & Madopar (levodopa + benserazide).

Many people find levodopa treatment very effective, but after long-term use its effectiveness may decrease, thus requiring the dosage to be increased. That and the development of involuntary movements (dyskinesias) is why some doctors delay treatment with levodopa for some time.

Once in the body, levodopa is broken down by molecules called enzymes - this reduces the amount of medication that can reach where it is needed in the brain. There are two main enzymes involved in the breakdown of levodopa: Peripheral dopa- decarboxylase (DDC) and catechol- O- methyltransferase (COMT). Inhibiting these enzymes can prevent levodopa's breakdown, optimizing its availability in the brain and improving symptom control. Unfortunately the effectiveness of levodopa can decline after years of treatment.

Consult your doctor if any of the above side effects occur or you experience any of the following;

  • Uncontrolled body movements (dyskinesias)
  • A fast heartbeat
  • Any unusual behavior or mood changes

Controlled release preparations of levodopa are recognized by the letters HBS or CR after the drug name. These preparations release the drug over a four to six hour period and may result in more even levels of levodopa in the blood. They maybe used when a person with Parkinson’s is experiencing wearing off of the dose of the standard levodopa. They can also be taken before going to bed to reduce stiffness and immobility during the night.

Failure to respond to levodopa may suggest that the disorder is not typical Parkinson's disease, but a Parkinson's disease- like disorder, and further medical assessments may be required.

Dopamine Agonists

Dopamine agonists stimulate the dopamine receptors rather than replacing dopamine. Dopamine receptor agonists are drugs that have a structure very similar to dopamine. Because of this similarity, they are able to mimic the action of dopamine rather than replenish the inadequate supply of dopamine in the way levodopa does.

Dopamine Agonists include - Bromocriptine (like- Proctinal & Parlodel), Carbergoline (like- Carberlin, Cabgol), Ropinirole (like-Requip, Ropark, Ropiro), Pramipexole (like- Pramipex, Pramirol), Lisuride (Dopergin)

The drugs are usually started at a low dose and increased slowly to reduce any possible side effects. Dopamine agonists are best taken with meals.

Several clinical studies have shown that dopamine agonists can be effective treatments for several years when used alone and the likelihood of developing dyskinesias is reduced while people remain on a dopamine agonist alone or in combination with a low dose of levadopa. Thus, enabling the clinician to save levodopa for the later management of Parkinson’s.

Possible side effects of these drugs include; nausea and vomiting, confusion and hallucinations, dizziness or lightheadedness and dry mouth.

Dopaminergics / Amantadine

Dopaminergic drugs or Amantadine does several different things, but its main beneficial effect may be to promote the release of dopamine and to allow it to stay longer at its site of action. They are used to treat Parkinson’s disease by improving muscle control and reducing stiffness, shakiness and shuffling.

Common Amantadine preparations include-Symmetrel, Amantrel

Amantadine can be used as a monotherapy i.e. used alone, in the early stages of PD, especially in younger people. Amantadine may have a stimulatory effect and can help some people with tiredness. It may sometimes help reduce dyskinesias.

Common side effects include; nausea, insomnia, dizziness or lightheadedness, swelling of the ankles, a mottled appearance on the skin of the lower leg. Contact your doctor if any of the above side effects persist or become troublesome.

Anticholinergics

Anticholinergics block the action of acetylcholine, a neurotransmitter that seems to work in balance with dopamine. Because dopamine is in short supply in the brains of people with Parkinson’s, this balance is upset. Blocking acetylcholine restores this balance and helps diminish some of the symptoms of Parkinson’s.

Common Anticholinergic preparations include; Pacitane, Kemadrine, Bexol

Anticholinergics are an older form of medication that are rarely used now although they are sometimes prescribed on their own to treat younger people in the early stages of Parkinson’s who have mild symptoms. They are most effective on tremor. They also may be used to reduce saliva production in people who experience drooling.

They should not be given to older people because there is an increased risk of confusion. They can also cause dry mouth, constipation and blurring of vision.

If you have glaucoma you should consult your doctor before taking this drug.

Mono Amine Oxidsae Type (MAO-B) Inhibitors

Monoamine oxidase type B inhibitors (MAO-B Inhibitors), inhibit or slow down the metabolism of dopamine, by blocking the enzyme MAO-B ;the enzyme that normally breaks down dopamine in the brain.

This activity of MAO-B inhibitors prolongs the potential action of dopamine by increasing the level of natural dopamine (derived from natural levodopa) when used as a treatment in monotherapy. When used in combination with levodopa medication, it increases the level of levodopa-derived dopamine within the brain, thus making the dose last longer or reduce the amount required.

MAO-B Inhibitors include Selegiline (like- Selgin, Eldepryl)


Although these drugs have few reported side effects, they should be used with caution when used in combination with antidepressants and with cold and cough preparations containing dextromethorphan.

COMT Inhibitors

COMT inhibitors are a new class of medications and work by blocking an enzyme called catechol-O-methyl transferase (COMT) which breaks down levodopa. As a result they slow the destruction of levodopa in the body allowing more levodopa to pass into the brain to be converted into dopamine. This can improve and lengthen the response to each levodopa dose, thus increasing the amount of time when the symptoms of Parkinson's disease are well controlled.


COMT Inhibitors include; Entacapone (Entacom, Adcapone, Comtan), Tolcapone (Tasmar)


These drugs are particularly effective in people who are experiencing on-off fluctuations. When used with levodopa, they can reduce the daily off time and increase the on time. In many cases, the levodopa dose and dosing frequency can also be reduced. COMT Inhibitors are also available in combination with Levodopa- Carbidopa.

Be aware that other drugs, for Parkinson’s or other conditions, can affect the action of these drugs. Most Parkinson’s drugs can be taken with COMT inhibitors, except Apomorphine.

Please Note : Regular blood tests to monitor liver function are necessary when taking Tolcapone, a type of COMT inhibitor.

Possible side effects include dyskinesias, nausea and vomiting, sleep problems, constipation or diarrhea. Urine can become discolored due to the substances used in the drugs, but this discolouration is harmless. An increase in side effects after starting a COMT inhibitor should be discussed with the doctor, reducing the levadopa dose can often help in this situation.

Adjunct Therapy for PD

While the line of treatment for PD involves drugs or medication and surgery for some cases, Exercise & Therapy; called Adjunct treatment; play a very important in the management and rehabilitation. For more info click here

Every Parkinson’s experience is unique. The symptoms and progression will vary from person to person. Living with Parkinson’s requires an individualized holistic approach which includes all aspects of ones life. Adjunct treatment helps one cope with daily living and attaining optimal benefits from this can significantly impact one’s quality of life.

It is important to note however that as the recipient of this treatment you play the most central role in its dispensation too .It is therefore vital for you to be an active participant in managing the disease. Care partners can also be involved.