Antiparkinson drugs are medicines that relieve the symptoms of Parkinson's disease and other forms of parkinsonism.
Parkinsonism is a group of disorders that share four main symptoms: tremor ortrembling in the hands, arms, legs, jaw, and face; stiffness or rigidity ofthe arms, legs, and trunk; slowness of movement (bradykinesia); and poor balance and coordination. Parkinson's disease is the most common form of parkinsonism.
All types of parkinsonism occur when nerve cells in a particular part of thebrain die or lose the ability to function. These cells normally produce a chemical called dopamine, that helps relay signals to different parts of the brain. This process is important in producing smooth, coordinated movement throughout the body. When dopamine-producing cells are lost, normal movement becomes impossible. In people with late-stage Parkinson's disease, 80% or more ofthese important cells are dead or impaired.
There is no cure for Parkinson's disease or other forms of parkinsonism but several drugs help relieve the symptoms. Some drugs, such as levodopa, replenish dopamine in the brain. Others mimic the role of dopamine or block the effects of other chemicals that cause problems in the brain when dopamine levelsdrop. Levodopa is one of the drugs used. It can either be used alone or in combination with carbidopa, to restore dopamine levels in the brain. Carbidopahelps make levodopa more effective and reduces some of the side effects thatoccur. In addition, antidyskinetics and anticholinergics, such as benztropineand trihexyphenidyl, are also used. These block the effects of other brain chemicals, thereby reducing some of the involuntary tremors.
All antiparkinson drugs are available only with a physician's prescription. They are sold in tablet (regular and extended-release), liquid, extended-release capsule, and injectable forms. The recommended dosage depends on the typeof antiparkinson drug. Finding the correct dose for a particular patient is aprocess that may take time and patience. The physician tries to tailor the treatment to the patient, taking into account what symptoms the patient has and how much the symptoms interfere with normal life. No two patients react thesame to a particular drug, so a person may need to try different drugs and different dosages before finding the best treatment.
Always take antiparkinson drugs exactly as directed. Never take larger or more frequent doses. Do not stop taking this medicine without first checking with the physician who prescribed it. Gradually tapering the dose may reduce thechance of side effects and prevent symptoms from getting worse.
Antiparkinson drugs may interact with medicines used during surgery, dental procedures, or emergency treatment. These interactions could increase the chance of side effects. Anyone who is taking antiparkinson drugs should be sure to tell the health care professional in charge before having any surgical or dental procedures or receiving emergency treatment. In addition, a physician should be consulted regarding any special dietary requirements for the patient.
Taking levodopa over a long time can lead to a problem called the "on-off" effect, in which a patient suddenly becomes unable to move. The effect may lastonly a few minutes or as long as several hours. When it ends, the patient isable to move normally again, but the effect may occur again and again without warning. A patient who experiences this problem should check with a physician. Another possible problem with long-term use of levodopa is called the "wearing-off" effect. With this effect, patients notice more pronounced symptomsas each dose wears off. Changing the dose of the medicine and the frequencywith which it is taken may help prevent this effect. Patients who have this problem should check with their physicians and should not change the dose of their medicine themselves.
Antiparkinson drugs may cause false results on some urine tests for sugar orketones. Persons with diabetes who take this medicine should check with theirphysicians. Women who are pregnant or who may become pregnant should check with their physicians before using any antiparkinson drug. Women who are breastfeeding should check with their physicians before using any antiparkinson drug.
Antiparkinson drugs may add to the effects of alcohol and other drugs that slow down the central nervous system. Taking antiparkinson drugs with certain other drugs may affect the way the drugs work or may increase the chance of side effects. Be sure to check with a physician or pharmacist before combiningantiparkinson drugs with any other prescription or nonprescription (over-the-counter) medicine. The most common side effects of antidyskinetics are drowsiness; nausea and vomiting; constipation; difficult or painful urination; drymouth, nose, or throat; blurred vision; increased sensitivity of the eyes tolight; and decreased sweating. These problems usually go away as the body adjusts to the drug and do not require medical treatment unless they continue orthey interfere with normal activities.
More serious side effects are rare, but may occur. Check with the physician who prescribed the medicine as soon as possible if confusion, eye pain, or skin rash occur.