Secondary parkinsonism results from a medication or illness that causes a drop in the amount of the neurotransmitter dopamine, producing symptoms similar to Parkinson's disease, such as tremors and shuffling movements. The Parkinson's Disease Society points out that 7 percent of secondary parkinsonism cases result from specific drugs that affect dopamine, and is called drug-induced parkinsonism. Since the symptoms of drug-induced parkinsonism can debilitate patients, finding the right treatment is important to eliminate these symptoms.
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Stopping the Drug
If a doctor suspects that a specific drug caused the parkinsonism, she may recommend that the patient stop taking it. If a person suspects that her medication causes parkinsonism, she should not stop using that medication without discussing it with her doctor first. The Parkinson's Disease Society explains that 60 percent of people who stop taking the medication that causes the drug-induced parkinsonism recover within two months.
For some patients, stopping the drug immediately is not an option. The doctor may gradually take the patient off the medication if there are possible problems from an abrupt withdrawal. If the patient cannot come off the medication, the doctor may either adjust the dosage or switch the patient to another medication that treats the same condition.
The Parkinson's Disease Society notes that if a drug-induced parkinsonism patient cannot stop taking the offending medication, his doctor may put him on an anticholinergic drug, a type of drug used to treat Parkinson's disease. Anticholinergics work by decreasing the activity of acetylcholine, another neurotransmitter. The activity of acetylcholine and dopamine are linked, so if the activity of acetylcholine goes down, the activity of dopamine goes up. MayoClinic.com lists benztropine and trihexyphenidyl as anticholinergic options for drug-induced parkinsonism. Side effects include dry mouth and eyes, constipation, memory problems, confusion and difficulty urinating.
MedlinePlus explains that patients with drug-induced parkinsonism may need to take medications used for Parkinson's disease to manage their symptoms. One option includes levadopa, the precursor of dopamine. When patients take levadopa, the drug passes through the blood-brain barrier, a protective layer around the brain, and converts to dopamine. Patients may take another drug, carbidopa, with levadopa. Carbidopa prevents levadopa from converting into dopamine before it crosses the blood-brain barrier, as the dopamine molecule is too large to pass through that layer. Patients taking levadopa may have involuntary movements as a side effect.
Some drug-induced parkinsonism patients may take dopamine agonists, a type of drug that acts like dopamine, causing the brain to respond as it would to actual dopamine. Unlike levadopa, dopamine agonists do not increase the amount of dopamine in patients' brains. Options for dopamine agonists include ropinirole, pramipexole and bromocriptine. Side effects of dopamine agonists include hallucinations and low blood pressure when standing.
A third Parkinson's disease medication option for drug-induced parkinsonism patients, MAO B inhibitors prevent the breakdown of dopamine by inhibiting the activity of the enzyme monoamine oxidase B, or MAO B. Options of MAO B inhibitors include selegiline and rasagiline. Side effects include hallucinations, confusion, dizziness and headaches.