Side Effects of Medication
Thanks to drug treatment, people with Parkinson's disease can lead normal, productive lives for many years. However, like all drugs, Parkinson's medications are not without side effects. Some are obvious and occur soon after you start taking the drug, but others may be more subtle and appear only after you’ve been on a medication a while.
Among the most widely used Parkinson’s medications, there are specific side effects you should be aware of after you or your loved one has been taking them for a few months or more.
Parkinson's Disease Treatment Side Effects: Dopamine Agonists
Parkinson’s disease is caused by a deterioration of nerve cells in certain parts of the brain that produce a neurotransmitter called dopamine. Parkinson's medications known as dopamine agonists control many of the symptoms of Parkinson’s disease by mimicking the actions that dopamine is responsible for. Usually, this medication is prescribed in the early stages of the disease. Drugs in this category include:
· Mirapex (pramipexole)
· Requip (ropinirole)
· Parlodel (bromocriptine)
· Permax (pergolide) — no longer available in the United States.
The short-term side effects of this type of Parkinson's medication may include nausea, sleep disturbances such as insomnia or vivid dreams, low blood pressure, and chest or abdominal pain. But perhaps the most troubling side effect associated with dopamine agonists is the potential for high-risk behaviors, such as compulsive gambling or having indiscriminate sex.
In one recent study, doctors at the Mayo Clinic reviewed the medical records of 267 people with Parkinson’s disease. Of the 66 people who were taking a dopamine agonist, seven — more than 10 percent — had started engaging in compulsive gambling or excessive sexual activity after they began taking the Parkinson's medication. Of those experiencing this side effect, the behavior was clearly pathological and disabling for at least five. In some cases, the abnormal behavior appeared within just two or three months after the patient started taking the Parkinson's medication, although for other people, it took up to a year or two for the changes in behavior to show up. Parkinson's patients who were not taking dopamine agonists did not develop these problems.
Discontinuing the dopamine agonist or lowering its dose seems to end the harmful behavior in those who experience this side effect. If you or someone you love is taking one of these drugs, watch for any increase in risky behavior and if you note any such behavior, tell his or her doctor right away so that changes can be made.
Parkinson's Disease Treatment: Carbidopa/Levodopa
Sold under the brand name Sinemet, Atamet, or Parcopa, the combination of carbidopa/levodopa is considered the “gold standard” of drug treatment for Parkinson’s disease and has improved life for millions of people with Parkinson's disease. Unfortunately, however, it’s not problem-free. After several years of taking this drug combo, some people develop abnormal, involuntary writhing movements called dyskinesias. Many people are willing to live with mild dyskinesias as long as their Parkinson’s symptoms are under control. However, more serious dyskinesias may be modified by taking smaller overall doses of carbidopa/levodopa or by taking smaller doses at shorter intervals, keeping the overall dose the same.
Also, while carbidopa/levodopa and other Parkinson’s disease medications can control symptoms for a while, they do not keep the disease from progressing. As time goes on and the illness becomes more severe, your response to carbidopa/levodopa may start to fluctuate, leading to what doctors call “on-off” periods. As your “on” response times grow shorter, you may find it harder to walk, eat, bathe, or speak, even if it’s not yet time for the next dose of your medication.
When this happens, your doctor may change your drug dose or schedule, or may prescribe a medication called Stalevo, that combines carbidopa/levodopa with a drug called entacapone, prolonging the action of levodopa in the brain by as much as 10 percent and resulting in longer “on” periods.
Diet may also make a difference. Protein can interfere with the absorption of levodopa from the digestive tract into the bloodstream. Some people find that taking their medication at least 30 minutes before or 60 minutes after a meal enhances their response to the drug.
Parkinson's Disease Treatment: COMT Inhibitors
Comtan (entacapone) and Tasmar (tolcapone) belong to a category of agents called COMT inhibitors. They’ve been associated with diarrhea after a few months of use. Tasmar is prescribed much less frequently than Comtan because it has been linked to liver failure in some people. If you take Tasmar, your doctor will most likely want to perform blood work every few months to monitor your liver function.
Good communication with your doctor is the key to preventing or minimizing most of these side effects from Parkinson's medication: Alert your doctor as soon as anything unusual occurs. Often the problem can be solved by changing the medication dose or schedule, or by substituting another drug. In general, it’s a good idea to keep track of all the drugs you’re taking and review them with your doctor at every visit.
Last Updated: 06/10/2009
FYI: APDA Asks – Is there a connection between Melanoma, Levodopa and PD?
The following article was written by Diane Church and appeared in the APDA online newsletter recently
LEVODOPA, MELONOMA, AND PARKINSON’S DISEASE: IS THERE A CONNECTION?
by Diane L. Church, PhD
New Hampshire APDA Information & Referral Center Coordinator
Levodopa was approved as a treatment for Parkinson’s disease in 1968 by the US Food and Drug Administration. In the form of carbidopa-levodopa (Sinemet®), it remains the most common treatment for Parkinson’s nearly 45 years later.
In 1972, the case of a PD patient who was treated with levodopa and suffered recurrent malignant melanoma skin cancer was reported. Other cases were subsequently published, and by 1976 it was announced that use of levodopa in Parkinson’s patients with melanoma was contraindicated.(3) However, studies had not answered the question: Was the occurrence of melanoma in Parkinson’s patients actually caused by levodopa, or was it a coincidence?
At the time, it seemed plausible that there could be an association between levodopa treatment and melanoma incidence: Levodopa is the substrate for the synthesis of both dopamine and melanin, which is the substance that accumulates in the darkly pigmented cells of melanoma.(2,3,6). Numerous studies (1-6) have now shown that people with Parkinson’s are at higher risk for melanoma, but that the increased incidence of melanoma is not related to any PD medication. Instead, it appears that “melanoma and PD might have shared environmental or genetic risk factors or pathogenic pathways.”(4)
Surprisingly, the Physician’s Desk Reference (PDR) still states that carbidopa-levodopa is contraindicated for those with undiagnosed skin lesions or a history of melanoma! It is no wonder that many in the Parkinson’s community, as well as numerous medical personnel who do not specialize in PD, still believe that there is a causal link between levodopa and melanoma. Unfortunately, many who would have received relief of their PD symptoms by taking levodopa have avoided this medication for fear of getting melanoma.
More on Melanoma from the National Institutes of Health (NIH):
“A mole, sore, lump, or growth on the skin can be a sign of melanoma or other skin cancer. A sore or growth that bleeds, or changes in skin coloring may also be a sign of skin cancer.
The ABCDE system can help you remember possible symptoms of melanoma:
Asymmetry: One half of the abnormal area is different from the other half.
Borders: The edges of the growth are irregular.
Color: Changes from one area to another, with shades of tan, brown, or black, and sometimes white, red, or blue or a mix of colors within one sore.
Diameter: The spot is usually (but not always) larger than 6 mm in diameter — about the size of a pencil eraser.
Evolution: The mole keeps changing appearance.
The key to successfully treating melanoma is recognizing symptoms early. You might not notice a small spot if you don’t look carefully. Have yearly body checks by a dermatologist, and examine your skin once a month. Use a hand mirror to check hard-to-see places. Call your doctor if you notice anything unusual.”
The NIH also states that the risk of developing melanoma increases with age, and that you are more likely to develop melanoma if you:
- Have fair skin, blue or green eyes, or red or blond hair
- Live in sunny climates or at high altitudes
- Spent a lot of time in high levels of strong sunlight or use tanning devices
- Have close relatives with a history of melanoma
Some Take-Home Messages
1) Levodopa treatment is NOT associated with an increase in diagnosis of melanoma or other cancers.
2) People with Parkinson’s:
- have an estimated 2- to 6-fold increased risk of melanoma
- have a reduced risk of most other types of cancer
3) Melanoma is rare in the general population (based on 2007-2009 data, only 2% of those born today will be diagnosed with melanoma in their lifetimes.(8)
4) The estimated lifetime melanoma rate for those with PD is therefore 4-12%.
5) Malignant melanoma is a curable disease if treated early. If left untreated, it is potentially fatal.
1. Bertoni JM, Arlette JP, Fernandez HH, et al. Increased melanoma risk in Parkinson disease: a prospective clinicopathological study. Arch Neurol 2010; 67:347-352
2. Driver JA, Logroscino G, Buring JE, et al. A prospective cohort study of cancer incidence following the diagnosis of Parkinson’s disease. Cancer Epidemiol Biomarkers Prev 2007; 16: 1260-1265
3. Ferreira JJ, Neutel D, MestreT et al. Skin Cancer and Parkinson’s Disease (Review). Movement Disorders 2010; 25: 129-148.
4. Liu R, Gao, X, Lu Y, Chen, H. Meta-analysis of the relationship between Parkinson disease and melanoma. Neurology 2011; 76: 2002-2009
5. Weiner WJ, Singer C, Sanchez-Ramos JR, Goldenberg JN. Levodopa, melanoma, and Parkinson’s disease. Neurology 1993; 43: 674-677
6. Zannetti R, Rosso S, Loria DI. Parkinson’s Disease and Cancer (Commentary) Cancer Epidemiol Biomarkers Prev 2007; 16: 1081
7. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001853/ (accessed August 8, 2012)
8. http://seer.cancer.gov/statfacts/html/melan.html (accessed August 8, 2012)
Reprinted with permission from the Parkinson’s Companion (A publication of the APDA Information & Referral Center at Dartmouth-Hitchcock Medical Center, Lebanon, NH), Fall 2012.