Parkinson's Disease: How Medicines Can Ease Symptoms
There's good reason to stay positive if someone has been diagnosed with Parkinson's disease. She should be able to benefit from a combination of drugs, exercise, and rehabilitative strategies such as physical, occupational, and speech therapy. Down the road, brain surgery might be an option. Finding the right balance of drugs is challenging and can take time, but in the past dozen years, new medicines have arrived that maximize symptom relief while reducing side effects.
Drugs for Parkinson's disease
Because Parkinson's disease results from the death of brain cells that produce dopamine, nearly all current drug therapies try to replace this important nerve chemical or protect it from enzymes in the body that break it down.
- Levodopa (sold as Sinemet or generic levodopa/carbidopa) dramatically liberated Parkinson's disease patients from wheelchairs when it first became available in the 1960s. Converted within the brain into dopamine, this drug is still the gold standard therapy for alleviating the core Parkinson's motor symptoms of slowness, stiffness, and tremor.
- Dopamine agonists (Apokyn, Mirapex, Parlodel, Requip) are compounds that can activate the same receptor as dopamine, thus mimicking its effects. These are less potent than Sinemet but generally cause fewer long-term side effects. Many early Parkinson's patients start out on Mirapex or Requip alone. Still, dopamine agonists are most commonly used in combination with Sinemet.
- MAO-B inhibitors (Azilect, Eldepryl, Zelapar) enhance dopamine's effects by preventing its breakdown within the brain.
- COMT inhibitors (Comtan, Tasmar) are prescribed with levodopa. They prolong its effects by shielding it from being degraded in the bloodstream.
- Amantadine (Symmetrel) is an antiviral drug thought to boost the release of dopamine in the brain.
- Anticholinergics (such as Artane, Cogentin) help relieve tremor and drooling by adjusting the balance in the brain between dopamine and another brain chemical called acetylcholine. These drugs are used less often in older patients because of side effects.
When to start Parkinson's drugs, including levodopa
It's recommended that a patient begin medications when Parkinson's disease symptoms begin significantly interfering with everyday activities at work or at home. Your family member's doctor may prescribe levodopa from the start or, if symptoms are still minor, begin with a dopamine agonist, an MAO-B inhibitor, or both. All Parkinson's patients eventually require levodopa, and the response to treatment usually unfolds in two phases.
Levodopa can work wonders in the early years. If your family member has run-of-the-mill Parkinson's disease, you can expect a "honeymoon" period during which levodopa provides good to excellent relief of core motor symptoms. Side effects are few.
Typically, activities that gave a person trouble before treatment began -- say, writing a check, making dinner, or chopping wood -- again feel smooth and easy. How long this honeymoon goes on varies from patient to patient, but it may last anywhere from two to seven years.
Red flag: A failure to respond well to levodopa (or dopamine agonists) could be a sign that your family member doesn't have Parkinson's disease and instead has one of several look-alike disorders. If her motor function doesn't seem to have improved from taking the drug, talk to her doctor about whether she should see a movement disorder specialist.
As Parkinson's progresses, complications arise
Once a patient has moved beyond the honeymoon phase of levodopa therapy, the drug-dosing schedule that the doctor prescribes is designed to keep blood levels of dopamine on an even keel throughout the day. Too little dopamine may leave your family member stiff and frozen in the middle of the grocery store; too much dopamine, and the wriggly dyskinesias kick in. So it's critical for her to try to always take the meds on time.
After roughly five years of taking levodopa, about 40 to 50 percent of people with Parkinson's disease develop long-term side effects called motor complications:
- Motor fluctuations. The benefit of each pill lasts a shorter time, and as the effect fades at the end of the dose, the patient's stiffness, slowness, or shakiness returns. This "wearing off" phenomenon seems to be connected with the continuing loss of dopamine-producing brain cells, which would otherwise store the dopamine supplied by levodopa therapy and release it in a natural way. So patients become highly sensitive to changes in their blood levels of the drug.
Over time, the "wearing off" turns unpredictable, occurring even in the middle of a dosing cycle when you wouldn't expect it, says nurse practitioner Julie Carter, who is associate director of the Parkinson Center of Oregon in Portland. Patients suddenly fluctuate from being "on" -- where symptoms are controlled -- to being "off," where symptoms worsen. Or sometimes they don't respond to a dose at all, Carter says.
- Dyskinesias. When "wearing off" begins, the physician will either give the patient more levodopa or shorten the interval between doses from one pill every, say, eight hours to one every six hours. But having too much dopamine in the blood can produce a side effect known as dyskinesia: involuntary and random fidgety, writhing movements of the patient's head, face, torso, arms, or leg s. Although dyskinesias aren't painful, for some patients, they may be as troublesome as the Parkinson's disease itself.
To deal with these motor complications, the doctor may add on one or two drugs from the other classes of medications -- the dopamine agonists, MAO-B inhibitors, or COMT inhibitors -- to increase "on" time. That could reduce the amount of levodopa needed.
Gradually, over several years, the patient typically has to take more and more doses of medicine per day to squelch motor fluctuations, up to the point where it may be necessary, in advanced Parkinson's disease cases, to take levodopa every couple of hours.
Seeing a skilled specialist and reporting side effects are key
Your family member will need a drug treatment plan tailored to her specific needs to achieve the best results. That's why it's so important early on to try to see a movement disorders specialist, "who really knows the disease, and when and how to use which medications," says Kelly E. Lyons, a research associate professor of neurology at the University of Kansas Medical Center in Kansas City. "It makes a big difference long-term in how patients do."
In terms of side effects, it's important to recognize the difference between the wiggly, almost dance-like motions of dyskinesias and a Parkinson's tremor, which tends to shake at a fairly constant rhythm, says Lyons. "The tremor is actually a symptom of the disease. The dy skinesia is a side effect of the drugs," she says. If your family confuses the two things when communicating with the physician, it could lead him down the wrong path in adjusting the drug regimen.
Each Parkinson's disease medication comes with a range of potential adverse effects, and it's a good idea to be aware of the problems a patient may experience. For instance, levodopa and dopamine agonists may cause nausea, vomiting, sleepiness, or insomnia (which all usually fade with time), as well as dizziness or fainting from low blood pressure. In some patients with advanced Parkinson's disease, both kinds of drugs may also cause hallucinations and psychosis; this risk is greater with the dopamine agonists.
Side effects should be discussed with your family member's doctor. He can try adjusting the dose, switching to another drug, or adding on other treatments for the problem at hand. For more details on Parkinson's drugs and their side effects, visit the National Parkinson Foundation and download its free publication on medications.