What happens if I overdose Carbidopa/levodopa?
Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately.
Proper storage of Carbidopa/levodopa:
Store Carbidopa/levodopa at room temperature, between 68 and 77 degrees F (20 and 25 degrees C). Brief storage between 59 and 86 degrees F (15 and 30 degrees C) is permitted. Store away from heat, moisture, and light. Do not store in the bathroom. Keep Carbidopa/levodopa out of the reach of children and away from pets.
Overdose of Carbidopa/levodopa in details
Management of acute overdosage with Carbidopa/levodopa is the same as management of acute overdosage with levodopa. Pyridoxine is not effective in reversing the actions of Carbidopa/levodopa.
General supportive measures should be employed, along with immediate gastric lavage.
Intravenous fluids should be administered judiciously and an adequate airway maintained. Electrocardiographic monitoring should be instituted and the patient carefully observed for the development of arrhythmias; if required, appropriate anti-arrhythmic therapy should be given. The possibility that the patient may have taken other drugs as well as Carbidopa/levodopa should be taken into consideration. To date, no experience has been reported with dialysis; hence, its value in overdosage is not known.
Based on studies in which high doses of levodopa and/or carbidopa were administered, a significant proportion of rats and mice given single oral doses of levodopa of approximately 1500-2000 mg/kg are expected to die. A significant proportion of infant rats of both sexes are expected to die at a dose of 800 mg/kg. A significant proportion of rats are expected to die after treatment with similar doses of carbidopa. The addition of carbidopa in a 1:10 ratio with levodopa increases the dose at which a significant proportion of mice are expected to die to 3360 mg/kg.
What should I avoid while taking Carbidopa/levodopa?
Some people using Carbidopa/levodopa have fallen asleep during normal daytime activities such as working, talking, eating, or driving. Avoid driving or operating machinery until you know how Carbidopa/levodopa will affect you. Dizziness or severe drowsiness can cause falls or other accidents. Also avoid getting up too fast from a sitting or lying position, or you may feel dizzy. Get up slowly and steady yourself to prevent a fall.
Drinking alcohol with Carbidopa/levodopa can cause side effects.
Avoid taking iron supplements or eating a diet that is high in protein (protein sources include meat, eggs, and cheese). These things can make it harder for your body to digest and absorb Carbidopa/levodopa. Talk with your doctor or nutrition counselor about the best foods to eat while you are using Carbidopa/levodopa.
Carbidopa/levodopa warnings
Gastrointestinal and Gastrointestinal Procedure-Related Risks
Because Carbidopa/levodopa is administered using a PEG-J or naso-jejunal tube, gastrointestinal complications can occur.
These complications include bezoar, ileus, implant site erosion/ulcer, intestinal hemorrhage, intestinal ischemia, intestinal obstruction, intestinal perforation, pancreatitis, peritonitis, pneumoperitoneum, and post-operative wound infection. These complications may result in serious outcomes, such as the need for surgery or death.
Instruct patients to notify their healthcare provider immediately if they experience abdominal pain, prolonged constipation, nausea, vomiting, fever, or melanotic stool.
Falling Asleep During Activities of Daily Living and Somnolence
Patients treated with levodopa, a component of Carbidopa/levodopa, have reported falling asleep while engaged in activities of daily living, including the operation of motor vehicles, which sometimes resulted in accidents. Although many of these patients reported somnolence while on levodopa, some perceived that they had no warning signs (sleep attack), such as excessive drowsiness, and believed that they were alert immediately prior to the event. Some of these events have been reported more than one year after initiation of treatment.
Falling asleep while engaged in activities of daily living usually occurs in patients experiencing preexisting somnolence, although patients may not give such a history. For this reason, prescribers should reassess patients for drowsiness or sleepiness in Carbidopa/levodopa-treated patients, especially since some of the events occur well after the start of treatment. Prescribers should be aware that patients may not acknowledge drowsiness or sleepiness until directly questioned about drowsiness or sleepiness during specific activities. Patients who have already experienced somnolence or an episode of sudden sleep onset should not participate in these activities while taking Carbidopa/levodopa.
Before initiating treatment with Carbidopa/levodopa, advise patients about the potential to develop drowsiness and specifically ask about factors that may increase the risk for somnolence with Carbidopa/levodopa such as the use of concomitant sedating medications or the presence of sleep disorders. Consider discontinuing Carbidopa/levodopa in patients who report significant daytime sleepiness or episodes of falling asleep during activities that require active participation (e.g., conversations, eating). If Carbidopa/levodopa is continued, they should be advised to avoid driving and other potentially dangerous activities that might result in harm if the patient becomes somnolent.
Orthostatic Hypotension
Carbidopa/levodopa-treated patients were more likely to experience a decline in orthostatic blood pressure than patients treated with oral immediate-release carbidopa-levodopa in the controlled clinical study. Orthostatic systolic hypotension (≥30 mm Hg decrease) occurred in 73% of Carbidopa/levodopa-treated patients compared to 68% of patients treated with oral immediate-release carbidopa-levodopa in the controlled clinical study. Orthostatic diastolic hypotension (≥20 mm Hg decrease) occurred in 70% of Carbidopa/levodopa-treated patients compared to 62% of patients treated with oral immediate-release carbidopa-levodopa. Inform patients about the risk for hypotension and syncope. Monitor patients for orthostatic hypotension, especially after starting Carbidopa/levodopa or increasing the dose.
Hallucinations/Psychosis/Confusion
There is an increased risk for hallucinations and psychosis in patients taking Carbidopa/levodopa. In the controlled clinical trial, hallucinations occurred in 5% of Carbidopa/levodopa-treated patients compared to 3% of patients treated with oral immediate-release carbidopa-levodopa. Confusion occurred in 8% of Carbidopa/levodopa-treated patients compared to 3% of patients treated with oral immediate-release carbidopa-levodopa, and psychotic disorder occurred in 5% of Carbidopa/levodopa-treated patients compared to 3% of patients treated with oral immediate-release carbidopa-levodopa.
Hallucinations associated with levodopa may present shortly after the initiation of therapy and may be responsive to dose reduction in levodopa. Confusion, insomnia, and excessive dreaming may accompany hallucinations. Abnormal thinking and behavior may present with one or more symptoms, including paranoid ideation, delusions, hallucinations, confusion, psychosis, disorientation, aggressive behavior, agitation, and delirium.
Because of the risk of exacerbating psychosis, patients with a major psychotic disorder should not be treated with Carbidopa/levodopa. In addition, medications that antagonize the effects of dopamine used to treat psychosis may exacerbate the symptoms of Parkinson’s disease and may decrease the effectiveness of Carbidopa/levodopa.
Impulse Control/Compulsive Behaviors
Patients may experience intense urges to gamble, increased sexual urges, intense urges to spend money, binge or compulsive eating, and/or other intense urges, and the inability to control these urges while taking one or more of the medications, including Carbidopa/levodopa, that increase central dopaminergic tone and that are generally used for the treatment of Parkinson’s disease. In some cases, although not all, these urges were reported to have stopped when the dose was reduced or the medication was discontinued.
Because patients may not recognize these behaviors as abnormal, it is important for prescribers to ask patients or their caregivers specifically about the development of new or increased gambling urges, sexual urges, uncontrolled spending, binge or compulsive eating, or other urges while being treated with Carbidopa/levodopa. Consider reducing the dose or discontinuing Carbidopa/levodopa if a patient develops such urges.
Depression and Suicidality
In the controlled clinical trial, 11% of Carbidopa/levodopa-treated patients developed depression compared to 3% of oral immediate-release carbidopa-levodopa-treated patients.
Monitor patients for the development of depression and concomitant suicidal tendencies.
Withdrawal-Emergent Hyperpyrexia and Confusion
A symptom complex that resembles neuroleptic malignant syndrome (characterized by elevated temperature, muscular rigidity, altered consciousness, and autonomic instability), with no other obvious etiology, has been reported in association with rapid dose reduction, withdrawal of, or changes in dopaminergic therapy. Avoid sudden discontinuation or rapid dose reduction in patients taking Carbidopa/levodopa. If Carbidopa/levodopa is discontinued, the dose should be tapered to reduce the risk of hyperpyrexia and confusion.
Dyskinesia
Carbidopa/levodopa may cause or exacerbate dyskinesias. In the controlled clinical trial, dyskinesia occurred in 14% of Carbidopa/levodopa-treated patients compared to 12% of patients treated with oral immediate-release carbidopa-levodopa. The occurrence of dyskinesias may require a dosage reduction of Carbidopa/levodopa or other medications used to treat Parkinson’s disease.
Neuropathy
In clinical studies, 19 of 412 (5%) patients treated with Carbidopa/levodopa developed a generalized polyneuropathy. The onset of neuropathy could be determined in 13 of 19 patients. Most cases (12/19) were classified as subacute or chronic in onset. The neuropathy was most often characterized as sensory or sensorimotor. Electrodiagnostic testing performed in 16 patients was most often (15/16) consistent with an axonal polyneuropathy, and one patient was classified as having a demyelinating neuropathy. There was insufficient information to determine the potential role of vitamin deficiencies in the etiology of neuropathy associated with Carbidopa/levodopa.
Patients should have clinical assessments for the signs and symptoms of peripheral neuropathy before starting Carbidopa/levodopa. Monitor patients periodically for signs of neuropathy after starting Carbidopa/levodopa, especially in patients with pre-existing neuropathy and in patients taking medications or those who have medical conditions that are also associated with neuropathy.
Cardiovascular Ischemic Events
In clinical studies, myocardial infarction and arrhythmia were reported in patients taking carbidopa-levodopa. Ask patients about symptoms of ischemic heart disease and arrhythmia, especially those with a history of myocardial infarction or cardiac arrhythmias.
Melanoma
Epidemiological studies have shown that patients with Parkinson’s disease have a higher risk (2 to approximately 6-fold higher) of developing melanoma than the general population. Whether the increased risk observed was due to Parkinson’s disease or other factors, such as drugs used to treat Parkinson’s disease, is unclear. In the clinical studies, 2 of 416 (0.5%) Carbidopa/levodopa-treated patients developed melanoma.
Appropriately qualified health care providers (e.g., dermatologists) should perform periodic skin examinations to monitor for melanoma in patients receiving Carbidopa/levodopa.
Laboratory Test Abnormalities
Carbidopa/levodopa may increase the risk for elevated (above the upper limit of normal for the reference range) blood urea nitrogen (BUN) and creatine phosphokinase (CPK). In the controlled clinical trial, the shift from a low or normal value at baseline to an increased BUN value was greater for Carbidopa/levodopa-treated patients (13%) than for patients treated with oral immediate-release carbidopa-levodopa (4%). The shift from a low or normal value at baseline to an increased CPK value was greater for Carbidopa/levodopa-treated patients (17%) than for patients treated with oral immediate-release carbidopa-levodopa (7%). The incidence of patients with a markedly increased BUN (≥10 mmol/L; ≥28 mg/dL) was greater for patients treated with Carbidopa/levodopa (11%) than that for patients treated with oral immediate-release carbidopa-levodopa (0%). The incidence of patients with an increased CPK (>3 times the upper limit of normal) was greater for patients treated with Carbidopa/levodopa (9%) than that for patients treated with oral immediate-release carbidopa-levodopa (0%).
Patients taking levodopa or carbidopa-levodopa may have increased levels of catecholamines and their metabolites in plasma and urine giving false positive results suggesting the diagnosis of pheochromocytoma in patients on levodopa and carbidopa-levodopa.
Glaucoma
Carbidopa-levodopa may cause increased intraocular pressure in patients with glaucoma. Monitor intraocular pressure in patients with glaucoma after starting Carbidopa/levodopa.
What should I discuss with my healthcare provider before taking Carbidopa/levodopa?
Do not take Carbidopa/levodopa if you have used an MAO inhibitor such as isocarboxazid (Marplan), phenelzine (Nardil), or tranylcypromine (Parnate) within the past 14 days. Serious, life-threatening side effects can occur if you take Carbidopa/levodopa before the MAO inhibitor has cleared from your body.
You should not take this medication if you are allergic to carbidopa (Lodosyn) or levodopa (Larodopa), or if you have:
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narrow-angle glaucoma;
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unusual skin lesions that have not been checked by a doctor; or
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a history of malignant melanoma (skin cancer).
If you have any of these other conditions, you may need a dose adjustment or special tests:
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heart disease, high blood pressure, coronary artery disease, a heart rhythm disorder, or a prior heart attack;
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asthma, chronic obstructive pulmonary disease (COPD), or other breathing disorder;
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liver or kidney disease;
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an endocrine (hormonal) disease;
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a stomach or intestinal ulcer;
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wide-angle glaucoma; or
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depression or other mental illness.
Carbidopa/levodopa may cause you to fall asleep during normal daytime activities such as working, talking, eating, or driving. You may fall asleep suddenly, even after feeling alert. Tell your doctor if you have any problems with daytime sleepiness or drowsiness.
You may have increased sexual urges, unusual urges to gamble, or other intense urges while taking Carbidopa/levodopa. It is not known whether the medicine actually causes this effect. Talk with your doctor if you believe you have any intense or unusual urges while taking Carbidopa/levodopa.
Some people taking medicines for Parkinson's disease have developed skin cancer (melanoma). However, people with Parkinson's disease may have a higher risk than most people for developing melanoma. Talk to your doctor about your specific risk and what skin symptoms to watch for. You may need to have regular skin exams.
FDA pregnancy category C. It is not known whether Carbidopa/levodopa will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.
Carbidopa/levodopa may pass into breast milk and could harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.
The disintegrating tablet (such as Parcopa) may contain phenylalanine. Talk to your doctor before using this form of Carbidopa/levodopa if you have phenylketonuria (PKU).
Carbidopa/levodopa precautions
General
As with levodopa, periodic evaluations of hepatic, hematopoietic, cardiovascular, and renal function are recommended during extended therapy.
Patients with chronic wide-angle glaucoma may be treated cautiously with Carbidopa/levodopa provided the intraocular pressure is well controlled and the patient is monitored carefully for changes in intraocular pressure during therapy.
Information for Patients
Phenylketonurics
Phenylketonuric patients should be informed that Carbidopa/levodopa orally disintegrating tablet contains phenylalanine 1.6 mg per 25 mg/100 mg orally disintegrating tablet, 1.6 mg per 10 mg/100 mg orally disintegrating tablet, and 4.0 mg per 25 mg/250 mg orally disintegrating tablet.
Patients should be instructed not to remove Carbidopa/levodopa from the bottle until just prior to dosing. With dry hands, the tablet should be gently removed and immediately placed on the tongue to dissolve and be swallowed with the saliva.
The patient should be informed that Carbidopa/levodopa orally disintegrating tablet is an immediate-release formulation of Carbidopa/levodopa that is designed to begin release of ingredients within 30 minutes. It is important that Carbidopa/levodopa be taken at regular intervals according to the schedule outlined by the physician. The patient should be cautioned not to change the prescribed dosage regimen and not to add any additional antiparkinson medications, including other Carbidopa/levodopa preparations, without first consulting the physician.
Patients should be advised that sometimes a “wearing-off” effect may occur at the end of the dosing interval. The physician should be notified if such response poses a problem to lifestyle.
Patients should be advised that occasionally, dark color (red, brown, or black) may appear in saliva, urine, or sweat after ingestion of Carbidopa/levodopa. Although the color appears to be clinically insignificant, garments may become discolored.
The patient should be advised that a change in diet to foods that are high in protein may delay the absorption of levodopa and may reduce the amount taken up in the circulation. Excessive acidity also delays stomach emptying, thus delaying the absorption of levodopa. Iron salts (such as in multi-vitamin tablets) may also reduce the amount of levodopa available to the body. The above factors may reduce the clinical effectiveness of the levodopa or Carbidopa/levodopa therapy.
NOTE: The suggested advice to patients being treated with Carbidopa/levodopa is intended to aid in the safe and effective use of this medication. It is not a disclosure of all possible adverse or intended effects.
Laboratory Tests
Abnormalities in laboratory tests may include elevations of liver function tests such as alkaline phosphatase, SGOT (AST), SGPT (ALT), lactic dehydrogenase, and bilirubin. Abnormalities in blood urea nitrogen and positive Coombs test have also been reported. Commonly, levels of blood urea nitrogen, creatinine, and uric acid are lower during administration of Carbidopa/levodopa than with levodopa.
Carbidopa/levodopa may cause a false-positive reaction for urinary ketone bodies when a test tape is used for determination of ketonuria. This reaction will not be altered by boiling the urine specimen. False-negative tests may result with the use of glucose-oxidase methods of testing for glucosuria.
Cases of falsely diagnosed pheochromocytoma in patients on Carbidopa/levodopa therapy have been reported very rarely. Caution should be exercised when interpreting the plasma and urine levels of catecholamines and their metabolites in patients on levodopa or Carbidopa/levodopa therapy.
Drug Interactions
Caution should be exercised when the following drugs are administered concomitantly with Carbidopa/levodopa.
Symptomatic postural hypotension has occurred when Carbidopa/levodopa was added to the treatment of a patient receiving antihypertensive drugs. Therefore, when therapy with Carbidopa/levodopa is started, dosage adjustment of the antihypertensive drug may be required.
For patients receiving MAO inhibitors (Type A or B), see CONTRAINDICATIONS. Concomitant therapy with selegiline and Carbidopa/levodopa may be associated with severe orthostatic hypotension not attributable to Carbidopa/levodopa alone.
There have been rare reports of adverse reactions, including hypertension and dyskinesia, resulting from the concomitant use of tricyclic antidepressants and Carbidopa/levodopa.
Dopamine D2 receptor antagonists (e.g., phenothiazines, butyrophenones, risperidone) and isoniazid may reduce the therapeutic effects of levodopa. In addition, the beneficial effects of levodopa in Parkinson’s disease have been reported to be reversed by phenytoin and papaverine. Patients taking these drugs with Carbidopa/levodopa should be carefully observed for loss of therapeutic response.
Iron salts may reduce the bioavailability of levodopa and carbidopa. The clinical relevance is unclear.
Although metoclopramide may increase the bloavailability of levodopa by increasing gastric emptying, metoclopramide may also adversely affect disease control by its dopamine receptor antagonistic properties.
Carcinogenesis, Mutagenesis, Impairment of Fertility
In a two-year bioassay of Carbidopa/levodopa, no evidence of carcinogenicity was found in rats receiving doses of approximately two times the maximum daily human dose of carbidopa and four times the maximum daily human dose of levodopa.
In reproduction studies with Carbidopa/levodopa, no effects on fertility were found in rats receiving doses of approximately two times the maximum daily human dose of carbidopa and four times the maximum daily human dose of levodopa.
Pregnancy
Pregnancy Category C. No teratogenic effects were observed in a study in mice receiving up to 20 times the maximum recommended human dose of Carbidopa/levodopa. There was a decrease in the number of live pups delivered by rats receiving approximately two times the maximum recommended human dose of carbidopa and approximately five times the maximum recommended human dose of levodopa during organogenesis. Carbidopa/levodopa caused both visceral and skeletal malformations in rabbits at all doses and ratios of Carbidopa/levodopa tested, which ranged from 10 times/5 times the maximum recommended human dose of Carbidopa/levodopa to 20 times/10 times the maximum recommended human dose of Carbidopa/levodopa.
There are no adequate or well-controlled studies in pregnant women. It has been reported from individual cases that levodopa crosses the human placental barrier, enters the fetus, and is metabolized. Carbidopa concentrations in fetal tissue appeared to be minimal. Use of Carbidopa/levodopa in women of childbearing potential requires that the anticipated benefits of the drug be weighed against possible hazards to mother and child.
Nursing Mothers
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Carbidopa/levodopa orally disintegrating tablet is administered to a nursing woman.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Use of the drug in patients below the age of 18 is not recommended.
What happens if I miss a dose of Carbidopa/levodopa?
You may need to use extra medicine to make up a missed dose. Call your doctor for instructions if you stop your infusion or disconnect your pump for longer than 2 hours.
To avoid a missed dose, get your prescription refilled before you run out of medicine completely.
References
- DailyMed. "CARBIDOPA; ENTACAPONE; LEVODOPA: DailyMed provides trustworthy information about marketed drugs in the United States. DailyMed is the official provider of FDA label information (package inserts).". https://dailymed.nlm.nih.gov/dailyme... (accessed September 17, 2018).
- DrugBank. "levodopa". http://www.drugbank.ca/drugs/DB01235 (accessed September 17, 2018).
- DrugBank. "carbidopa". http://www.drugbank.ca/drugs/DB00190 (accessed September 17, 2018).
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Information checked by Dr. Sachin Kumar, MD Pharmacology
