Parkinson's Disease Symptoms Alleviated by Medications

Jan 6, 2011
Margi Desmond

PET Scan of Brain with Parkinson's Disease - Photo by Chris73

Medications that increase the level of dopamine in the brain help patients with Parkinson's Disease manage their symptoms.

There is no cure for Parkinson’s Disease; however, by increasing the level of dopamine in the brain, certain medications help to alleviate the symptoms associated with the disease. Those symptoms include tremor, bradykinesia (slowed movement), rigid muscles, impaired posture and balance, loss of automatic movements such as blinking and smiling, speech changes such as slurring and hesitating, and dementia.

Sinemet (Levodopa/Carbidopa)

Lovodopa is the most effective Parkinson’s medication. It passes into the brain and is converted to dopamine. Carbidopa ensures the lovodopa doesn’t prematurely convert to dopamine outside the brain and is also thought to prevent nausea in some patients. The benefit of lovodopa wears off as the disease progresses, thus requiring medication adjustments. Sinemet tablets are manufactured in three strengths:

Sinemet 25-100, yellow oval tablets containing 25 mg of carbidopa and 100 mg of levodopa. They are scored and coded 650 on one side and “Sinemet” on the other.
Sinemet 10-100, dark dapple-blue oval tablets containing 10 mg of carbidopa and 100 mg of levodopa. They are scored and coded 647 on one side and “Sinemet” on the other.
Sinemet 25-250, light dapple-blue oval tablets containing 25 mg of carbidopa and 250 mg of levodopa. They are scored and coded 654 on one side and “Sinemet” on the other.

The most common side effects of Sinemet include dyskinesias, other involuntary movements, and nausea. Other side effects include chest pain, asthenia, cardiac irregularities, hypotension, orthostatic hypotension, hypertension, syncope, phlebitis, palpitation, dark saliva, and gastrointestinal bleeding.

Dopamine Agonists

Dopamine agonists mimic the effects of dopamine on the brain and cause neurons to act as if dopamine is present. They don’t work as well as levodopa, but their effects sometimes last longer. These medications include:

Pramipexole (Mirapex) tablets available in 0.125 mg, 0.25 mg, 0.5 mg, 1 mg, and 1.5 mg dosages.
Ropinirole (Requip) tablets available in 0.25 mg, 0.5 mg, 1 mg, 2 mg, 3 mg, 4 mg, and 5 mg dosages.
Apomorphine (Apokyn) is a subcutaneous injectable dosage.

Side effects include hallucinations, sleepiness, water retention, and low blood pressure when standing. They may also increase risk of compulsive behaviors such as hypersexuality, compulsive gambling, and compulsive overeating.

Monoamine Oxidase B (MAO B) Inhibitors

Monoamine oxidase B (MAO B) is an enzyme in the brain that breaks down dopamine. Monoamine oxidase B (MAO B) inhibitors reduce this enzyme’s activity. These medications include:

Selegiline (Eldepryl) available in 5 mg capsules.
Rasagiline (Azilect) available in 0.5 mg and 1 mg tablets.

Side effects include confusion, headache, hallucinations, and dizziness. They can’t be used in combination with antidepressants, Cipro, St. John’s wort, or certain narcotics.

Catechol O-Methyltransferase (COMT) Inhibitors

Catechol O-methyltransferase (COMT) inhibitors block an enzyme that breaks down levodopa and are combined with carbidopa and levodopa therapy. Medications include:

Tolcapone (Tasmar) is available in 100 mg and 200 mg tablets. It has been linked to acute fulminant liver failure and is only used for patients who haven’t responded to other medications.
Entacapone (Comtan) is available in 200 mg tablets and doesn’t cause liver damage but may increase side effects including involuntary movements, nausea, hallucinations, and confusion.

Anticholinergics

Anticholinergics inhibit parasympathetic nerve impulses by blocking the neurotransmitter acetylcholine to its receptor. Medications include:

Benztropine (Cogentin) is administered either via intramuscular injection or intravenously. Effects can be seen within minutes.
Trihexyphenidyl (Artane) is available in 2 mg and 5 mg tablets and as a lime-mint flavored elixir.

In many patients the drug benefits to not outweigh the side effects which include fever, irregular heartbeats, anxiety, hallucinations, confusion, agitation, hyperactivity, and seizures.

Glutamate (NMDA) Blocking Drugs

Glutamate is a neurotransmitter in the brain responsible for sending signals between cells. Abnormally high amounts of glutamate can overexcite nerve cells. Glutamate (NMDA) blocking drugs limit glutamate activity. Medications include:

Amantadine (Symmetrel) is a light orange 100 mg triangular tablet usually taken twice daily. For unresponsive patients, dosages can be increased up to 400 mg daily.

Side effects include purple mottling of the skin and hallucinations.