Parkinson’s disease cannot be cured, but medications which increase or substitute for dopamine can significantly improve symptoms. However, the benefits of drugs may diminish or become less consistent over time.
Medications your doctor may prescribe include:
- Levodopa (combined with carbidopa), the most effective Parkinson’s disease medication, is a natural chemical that passes into your brain and is converted to dopamine. Side effects may include nausea or light-headedness (orthostatic hypotension).
An inhaled form of carbidopa-levodopa (Inbrija) may be helpful in managing symptoms that arise when oral medications suddenly stop working during the day.
Carbidopa-levodopa may also be given as an infusion (Duopa) through a feeding tube directly to the small intestine for patients with more-advanced Parkinson’s who still respond to carbidopa-levodopa, but who have a lot of fluctuations in their response. Placement of the tube requires a small surgical procedure. Risks associated with having the tube include the tube falling out or infections at the infusion site.
- Dopamine agonists which mimic dopamine effects in the brain are not as effective as levodopa. However, they last longer and may be used with levodopa to smooth the sometimes off-and-on effect of levodopa.
Some of the side effects of dopamine agonists are similar to the side effects of carbidopa-levodopa. But they can also include hallucinations, sleepiness and compulsive behaviours. If you are taking these medications and you behave in a way that is out of character for you, talk to your doctor.
- MAO B inhibitors may help prevent the breakdown of brain dopamine by inhibiting the brain enzyme monoamine oxidase B (MAO B). This enzyme metabolizes brain dopamine.
Side effects of MAO B inhibitors may include headaches, nausea or insomnia. When added to carbidopa-levodopa, these medications increase the risk of hallucinations. There are potentially serious but rare reactions when taken with antidepressants or certain narcotics.
- Catechol O-methyltransferase (COMT) inhibitors can mildly prolong the effect of levodopa therapy by blocking an enzyme that breaks down dopamine.
Side effects, including an increased risk of involuntary movements (dyskinesia), mainly result from an enhanced levodopa effect. Other side effects include diarrhoea, nausea or vomiting.
- Anticholinergics were used for many years to help control the tremor associated with Parkinson’s disease. However, their modest benefits are often offset by side effects such as impaired memory, confusion, hallucinations, constipation, dry mouth and impaired urination.
- Amantadine may be prescribed alone to provide short-term relief of symptoms of mild, early-stage Parkinson’s disease. It may also be given with carbidopa-levodopa therapy during the later stages of Parkinson’s disease to control involuntary movements (dyskinesia) induced by carbidopa-levodopa. Side effects may include a purple mottling of the skin, ankle swelling or hallucinations.
Your doctor may also recommend lifestyle changes, especially ongoing aerobic exercise.
Physical therapy, focusing on balance and stretching may help in some cases.
A speech-language pathologist may help with speech problems.