Medications for the Treatment of Parkinson's Disease
Prescription medications may include the following:
- Carbidopa-levodopa (Parcopa), or levodopa, generally regarded as the most effective Parkinson's disease medication, is a natural chemical that passes into the brain and is converted to dopamine. Levodopa is combined with carbidopa, which protects levodopa from premature conversion to dopamine outside you're the brain, thereby preventing nausea. Side effects include nausea or a drop in blood pressure when standing (may result in faintness). After years, as the disease progresses, the benefit from levodopa may become less stable, with a tendency to wax and wane ("wearing off"). in addition, involuntary movements (dyskinesia) after taking higher doses of levodopa may be experienced. The doctor may adjust doses or scheduling to mitigate these effects.
- Unlike levodopa, dopamine agonists don't change into dopamine. Instead, they mimic dopamine effects in the brain. They aren't as effective in treating symptoms as levodopa; however, they last longer and may be used with levodopa to smooth its sometimes fluctuating effect. Dopamine agonists include pramipexole (Mirapex) and ropinirole (Requip). A short-acting injectable dopamine agonist, apomorphine (Apokyn), is used for quick relief. The side effects of dopamine agonists are similar to carbidopa-levodopa, but also include hallucinations, swelling, sleepiness or compulsive behaviors such as hypersexuality, gambling and eating. A patient taking these medications who begins to behave in an uncharacteristic way should consult his or her doctor.
- MAO B inhibitors include selegiline (Eldepryl, Zelapar) and rasagiline (Azilect). They help prevent the breakdown of brain dopamine by inhibiting the brain enzyme monoamine oxidase B (MAO B). This enzyme metabolizes brain dopamine. Side effects are uncommon, but may rarely include nausea or headaches. When added to carbidopa-levodopa, these medications can increase the risk of hallucinations. These medications can't be used in combination with most antidepressants or certain narcotics, due to potentially serious reactions. Check with the doctor before taking any additional medications with a MAO B inhibitor.
- Entacapone (Comtan) is the primary medication among catechol O-methyltransferase (COMT) inhibitors. This medication mildly prolongs the effect of levodopa therapy by blocking an enzyme that breaks down levodopa. The side effects are primarily those due to an enhanced levodopa effect, including an increased risk of involuntary movements (dyskinesias). Tolcapone (Tasmar) is another COMT inhibitor but it is rarely prescribed due to a risk of serious liver damage and liver failure.
- Anticholinergics are used to help control the tremor associated with Parkinson's disease. Several anticholinergic medications are available, including benztropine (Cogentin) and trihexyphenidyl. However,as with all medications, benefits can be offset by side effects such as impaired memory, confusion, hallucinations, constipation, dry mouth and impaired urination.
- Doctors may prescribe amantadine alone to provide short-term relief of symptoms of mild, early-stage Parkinson's disease. It also may be added to carbidopa-levodopa therapy for people in the later stages of Parkinson's disease, to help control involuntary movements (dyskinesia) induced by carbidopa-levodopa. Side effects may include a purple mottling of the skin, ankle swelling or hallucinations.
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