SINEMET carbidopa and levodopa 25 mg; 100 mg Tablet, 100-count
🆔 Identity & classification
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🏷️ RxNorm drug class
This medicine belongs to the Aromatic Amino Acid Decarboxylation Inhibitor class.
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🏭 Manufacturer & labeler
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🩺 Clinical
Levodopa and carbidopa is used to treat the symptoms of Parkinson's disease and Parkinson's-like symptoms that may develop after encephalitis (swelling of the brain) or injury to the nervous system caused by carbon monoxide poisoning or manganese poisoning. Levodopa is in a class of medications called central nervous system agents. It works by being converted to dopamine in the brain (the natural substance that is low in Parkinson's and causes the symptoms of tremor, stiffness, and slowness of movement). Carbidopa is in a class of medications called decarboxylase inhibitors. It works by preven...
Read the full MedlinePlus article ↗- Levodopa is the medicine that actually works in your brain — it crosses into the brain and gets converted into dopamine, the chemical that Parkinson's disease depletes. The problem...
- What exactly does levodopa and carbidopa do, and why do I need both?
- Generally yes, but the timing and content of your meals can matter. High-protein foods — like large servings of meat, eggs, or dairy — can compete with levodopa for absorption in y...
- Can I eat normally while taking this medication?
Patient education
Supplement & herbal interactions
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💊 What it looks like
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🧪 Inactive Ingredients / Excipients
Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.
💡 Tap an ingredient (hover on desktop) to see what it is and why it’s used.
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UNII 35SW5USQ3G
A synthetic yellow dye used to color medicines. It helps make tablets, capsules, and liquids visually distinct so patients can easily identify their medication.
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UNII 70097M6I30
Magnesium stearate is a salt made from magnesium and stearic acid, a fatty substance. It's used in tablets and capsules as a lubricant and glidant to help ingredients flow smoothly during manufacturing and prevent sticking.
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UNII OP1R32D61U
Microcrystalline cellulose is a purified form of cellulose, a natural fiber from plant sources. It acts as a binder and filler in tablets and capsules, helping hold ingredients together and give the medicine its shape and size.
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UNII O8232NY3SJ
A plant-based carbohydrate derived from corn kernels. It acts as a filler to add bulk, a binder to hold ingredients together, and a disintegrant to help the tablet break apart in your stomach for absorption.
4 inactive ingredients listed in the exact product block matched to this NDC.
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ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.Inactive ingredient FAQ
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💲 Pricing
A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.
| Price system | Per ea | Per package |
|---|---|---|
| Retail pharmacies payNADAC · weekly | $1.424 | $142.36 / 100 tablets |
| Medicaid paysCMS SDUD · 12 mo | No recent Medicaid claims on file for this NDC — rare and low-volume NDCs are suppressed in the public data. | |
| Medicare drug plans payPart D · Q2 2026 | $1.30 | $129.81 / 100 tablets |
Where does this data come from?
🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| Carbidopa and levodopa 25 mg/1; 100 mg 00093-9702-01 | Teva | 100 tablets | $0.077 | AB | Availability likely | save 95% |
| Carbidopa and Levodopa 25 mg/1; 100 mg 00904-7501-61 | Major | 100 tablets | $0.077 | AB | Availability likely | save 95% |
| Carbidopa And Levodopa 25 mg/1; 100 mg 31722-0382-01 | Camber | 100 tablets | $0.077 | AB | Availability likely | save 95% |
| Carbidopa and Levodopa 25 mg/1; 100 mg 50228-0458-01 | ScieGen | 100 tablets | $0.077 | AB | Availability likely | save 95% |
| Carbidopa-levodopa 25 mg/1; 100 mg 52817-0391-00 | TruPharma, | 1000 tablets | $0.077 | AB | Availability likely | save 95% |
| Carbidopa and Levodopa 25 mg/1; 100 mg 59651-0457-01 | Aurobindo | 100 tablets | $0.077 | AB | Availability likely | save 95% |
| Carbidopa and Levodopa 25 mg/1; 100 mg 60687-0661-01 | American | 100 tablets | $0.077 | AB | Availability likely | save 95% |
| Carbidopa and Levodopa 25 mg/1; 100 mg 69367-0339-01 | Westminster | 100 tablets | $0.077 | AB | Availability likely | save 95% |
| Carbidopa-levodopa 25 mg/1; 100 mg 72888-0107-00 | Advagen | 1000 tablets | $0.077 | AB | Availability likely | save 95% |
| Carbidopa and Levodopa 25 mg/1; 100 mg 75907-0020-01 | Dr. | 100 tablets | $0.077 | AB | Availability likely | save 95% |
| Sinemet 25 mg/1; 100 mg 78206-0168-01 | Organon | 100 tablets | $1.424 | AB | Discontinued | — |
| Sinemet 25 mg/1; 100 mgthis 78206-0190-01 | Organon | 100 tablets | $1.424 | AB | Availability likely | — |
| Dhivy 25 mg/1; 100 mg 75854-0701-01 | Avion | 100 tablets | $3.614 | — | Availability likely | +154% |
| Carbidopa and Levodopa 25 mg/1; 100 mg 00615-8536-05 | NCS | 15 tablets | — | AB | FDA listed | — |
| Carbidopa and levodopa 25 mg/1; 100 mg 42291-0472-01 | AvKARE | 100 tablets | — | AB | FDA listed | — |
| Carbidopa and Levodopa 25 mg/1; 100 mg 50090-5969-01 | A-S | 90 tablets | — | AB | FDA listed | — |
| Carbidopa and Levodopa 25 mg/1; 100 mg 50090-6580-01 | A-S | 90 tablets | — | AB | FDA listed | — |
| Carbidopa and Levodopa 25 mg/1; 100 mg 50090-6725-00 | A-S | 90 tablets | — | AB | FDA listed | — |
| Carbidopa and levodopa 25 mg/1; 100 mg 50090-6727-00 | A-S | 90 tablets | — | AB | FDA listed | — |
| Carbidopa and Levodopa 25 mg/1; 100 mg 50090-7498-01 | A-S | 90 tablets | — | AB | FDA listed | — |
| Carbidopa and Levodopa 25 mg/1; 100 mg 50090-7499-00 | A-S | 90 tablets | — | AB | FDA listed | — |
| Carbidopa and Levodopa 25 mg/1; 100 mg 50268-0202-15 | AvPAK | 50 tablets | — | AB | FDA listed | — |
| Carbidopa and Levodopa 25 mg/1; 100 mg 55154-2643-00 | Cardinal | 10 tablets | — | AB | FDA listed | — |
| Carbidopa And Levodopa 25 mg/1; 100 mg 62756-0518-08 | Sun | 100 tablets | — | AB | FDA listed | — |
| Carbidopa And Levodopa 25 mg/1; 100 mg 63629-2356-01 | Bryant | 500 tablets | — | AB | Discontinued | — |
| Carbidopa And Levodopa 25 mg/1; 100 mg 63629-2357-01 | Bryant | 100 tablets | — | AB | Discontinued | — |
| Carbidopa-levodopa 25 mg/1; 100 mg 67046-1507-03 | Coupler | 30 tablets | — | AB | FDA listed | — |
| Carbidopa And Levodopa 25 mg/1; 100 mg 68071-2240-01 | NuCare | 100 tablets | — | AB | FDA listed | — |
| Carbidopa and Levodopa 25 mg/1; 100 mg 71205-0878-00 | Proficient | 100 tablets | — | AB | FDA listed | — |
| Carbidopa-levodopa 25 mg/1; 100 mg 71335-2588-01 | Bryant | 90 tablets | — | AB | FDA listed | — |
| Carbidopa and Levodopa 25 mg/1; 100 mg 71610-0647-60 | Aphena | 90 tablets | — | AB | FDA listed | — |
| Carbidopa and levodopa 25 mg/1; 100 mg 71610-0664-60 | Aphena | 90 tablets | — | AB | FDA listed | — |
| Carbidopa And Levodopa 25 mg/1; 100 mg 72865-0362-01 | XLCare | 100 tablets | — | AB | FDA listed | — |
| Carbidopa And Levodopa 25 mg/1; 100 mg 53401-0020-60 | Aphena | 90 tablets | — | AB | FDA listed | — |
Where does this data come from?
⏳ Availability & generic status
FDA-approved generic versions are listed, and recent pricing/market data suggests they may be available — see Therapeutic equivalents.
Where does this data come from?
📊 Medicare Part D spend CMS · PART D · 2026 (Q1)
📦 Packaging — all sizes for this product
| Package NDC | Description | Marketing start | Status |
|---|---|---|---|
| 78206-0190-01 You're viewing this | 100 TABLET in 1 BOTTLE (78206-190-01) | 2025-02-28 | Active |
📄 Full prescribing information FDA SPL
🎯 Indications and Usage ▾
INDICATIONS AND USAGE SINEMET is indicated in the treatment of Parkinson's disease, post-encephalitic parkinsonism, and symptomatic parkinsonism that may follow carbon monoxide intoxication or manganese intoxication. Carbidopa allows patients treated for Parkinson's disease to use much lower doses of levodopa. Some patients who responded poorly to levodopa have improved on SINEMET.
This is most likely due to decreased peripheral decarboxylation of levodopa caused by administration of carbidopa rather than by a primary effect of carbidopa on the nervous system. Carbidopa has not been shown to enhance the intrinsic efficacy of levodopa. Carbidopa may also reduce nausea and vomiting and permit more rapid titration of levodopa.
⏱️ Dosage and Administration ▾
DOSAGE AND ADMINISTRATION SINEMET 25-250 tablets are no longer marketed. For dosing with 25-250 strength, use another carbidopa and levodopa product. The optimum daily dosage of SINEMET must be determined by careful titration in each patient.
SINEMET tablets are available in a 1:4 ratio of carbidopa to levodopa (SINEMET 25-100) as well as 1:10 ratio (carbidopa and levodopa 25-250 and SINEMET 10-100). Tablets of the two ratios may be given separately or combined as needed to provide the optimum dosage. Studies show that peripheral dopa decarboxylase is saturated by carbidopa at approximately 70 to 100 mg a day.
Patients receiving less than this amount of carbidopa are more likely to experience nausea and vomiting. Management of Vitamin B 6 Levels Evaluate vitamin B 6 levels prior to initiating carbidopa/levodopa therapies, including SINEMET, periodically during treatment, and as clinically indicated (see WARNINGS, Vitamin B6 Deficiency and Seizures ). If vitamin B 6 levels are low, supplement to sufficient levels per standard of care.
Patients may initiate and continue treatment with SINEMET while supplementing vitamin B 6 . Usual Initial Dosage Dosage is best initiated with one tablet of SINEMET 25-100 three times a day. This dosage schedule provides 75 mg of carbidopa per day.
Dosage may be increased by one tablet every day or every other day, as necessary, until a dosage of eight tablets of SINEMET 25-100 a day is reached. If SINEMET 10-100 is used, dosage may be initiated with one tablet three or four times a day. However, this will not provide an adequate amount of carbidopa for many patients.
Dosage may be increased by one tablet every day or every other day until a total of eight tablets (2 tablets q.i.d.) is reached. How to Transfer Patients from Levodopa Levodopa must be discontinued at least twelve hours before starting SINEMET. A daily dosage of SINEMET should be chosen that will provide approximately 25% of the previous levodopa dosage.
Patients who are taking less than 1500 mg of levodopa a day should be started on one tablet of SINEMET 25-100 three or four times a day. The suggested starting dosage for most patients taking more than 1500 mg of levodopa is one tablet of carbidopa and levodopa 25-250 three or four times a day. Maintenance Therapy should be individualized and adjusted according to the desired therapeutic response.
At least 70 to 100 mg of carbidopa per day should be provided. When a greater proportion of carbidopa is required, one tablet of SINEMET 25-100 may be substituted for each tablet of SINEMET 10-100. When more levodopa is required, carbidopa and levodopa 25-250 should be substituted for SINEMET 25-100 or SINEMET 10-100.
If necessary, the dosage of carbidopa and levodopa 25-250 may be increased by one-half or one tablet every day or every other day to a maximum of eight tablets a day. Experience with total daily dosages of carbidopa greater than 200 mg is limited. Because both therapeutic and adverse responses occur more rapidly with SINEMET than with levodopa alone, patients should be monitored closely during the dose adjustment period.
Specifically, involuntary movements will occur more rapidly with SINEMET than with levodopa. The occurrence of involuntary movements may require dosage reduction. Blepharospasm may be a useful early sign of excess dosage in some patients.
Addition of Other Antiparkinsonian Medications Standard drugs for Parkinson's disease, other than levodopa without a decarboxylase inhibitor, may be used concomitantly while SINEMET is being administered, although dosage adjustments may be required. Interruption of Therapy Sporadic cases of hyperpyrexia and confusion have been associated with dose reductions and withdrawal of SINEMET. Patients should be observed carefully if abrupt reduction or discontinuation of SINEMET is required, especially if the patient is receiving neuroleptics.
(See WARNINGS .) If general anesthesia is required, SINEMET may be continued as long as the…
⛔ Contraindications ▾
CONTRAINDICATIONS Nonselective monoamine oxidase (MAO) inhibitors are contraindicated for use with SINEMET. These inhibitors must be discontinued at least two weeks prior to initiating therapy with SINEMET. SINEMET may be administered concomitantly with the manufacturer's recommended dose of an MAO inhibitor with selectivity for MAO type B (e.g., selegiline HCl) (see PRECAUTIONS, Drug Interactions ).
SINEMET is contraindicated in patients with known hypersensitivity to any component of this drug, and in patients with narrow-angle glaucoma.
⚠️ Warnings ▾
WARNINGS When SINEMET is to be given to patients who are being treated with levodopa, levodopa must be discontinued at least twelve hours before therapy with SINEMET is started. In order to reduce adverse reactions, it is necessary to individualize therapy. See DOSAGE AND ADMINISTRATION section before initiating therapy.
The addition of carbidopa with levodopa in the form of SINEMET reduces the peripheral effects (nausea, vomiting) due to decarboxylation of levodopa; however, carbidopa does not decrease the adverse reactions due to the central effects of levodopa. Because carbidopa permits more levodopa to reach the brain and more dopamine to be formed, certain adverse central nervous system (CNS) effects, e.g., dyskinesias (involuntary movements), may occur at lower dosages and sooner with SINEMET than with levodopa alone. All patients should be observed carefully for the development of depression with concomitant suicidal tendencies.
SINEMET should be administered cautiously to patients with severe cardiovascular or pulmonary disease, bronchial asthma, renal, hepatic or endocrine disease. As with levodopa, care should be exercised in administering SINEMET to patients with a history of myocardial infarction who have residual atrial, nodal, or ventricular arrhythmias. In such patients, cardiac function should be monitored with particular care during the period of initial dosage adjustment, in a facility with provisions for intensive cardiac care.
As with levodopa, treatment with SINEMET may increase the possibility of upper gastrointestinal hemorrhage in patients with a history of peptic ulcer. Vitamin B 6 Deficiency and Seizures Treatment with SINEMET may contribute to reduced vitamin B 6 levels. Higher doses of carbidopa/levodopa may increase the risk of vitamin B 6 deficiency.
Seizures associated with vitamin B 6 deficiency have been reported in the postmarketing setting in patients taking SINEMET. In these reported cases, seizures were refractory to traditional anti-seizure medications and only resolved after vitamin B 6 administration. Other symptoms of vitamin B 6 deficiency may occur, including depression, confusion, cheilosis, glossitis, dermatitis, anemia, and/or neuropathy.
Evaluate vitamin B 6 levels prior to initiation of SINEMET and periodically while on treatment or if symptoms associated with vitamin B 6 deficiency are identified. Supplement with vitamin B 6 as necessary. Falling Asleep During Activities of Daily Living and Somnolence Patients taking SINEMET alone or with other dopaminergic drugs have reported suddenly falling asleep without prior warning of sleepiness while engaged in activities of daily living (includes operation of motor vehicles).
Road traffic accidents attributed to sudden sleep onset have been reported. Although many patients reported somnolence while on dopaminergic medications, there have been reports of road traffic accidents attributed to sudden onset of sleep in which the patient did not perceive any warning signs, such as excessive drowsiness, and believed that they were alert immediately prior to the event. Sudden onset of sleep has been reported to occur as long as one year after the initiation of treatment.
Falling asleep while engaged in activities of daily living usually occurs in patients experiencing pre-existing somnolence, although some patients may not give such a history. For this reason, prescribers should reassess patients for drowsiness or sleepiness 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 should be advised to exercise caution while driving or operating machines during treatment with SINEMET. Patients who have already experienced somnolence or an episode of sudden sleep onset should not participate in these activities during treatment with SINEMET. Before…
🤒 Adverse Reactions ▾
ADVERSE REACTIONS The most common adverse reactions reported with SINEMET have included dyskinesias, such as choreiform, dystonic, and other involuntary movements, and nausea. The following other adverse reactions have been reported with SINEMET: Body as a Whole Chest pain, asthenia. Cardiovascular Cardiac irregularities, hypotension, orthostatic effects including orthostatic hypotension, hypertension, syncope, phlebitis, palpitation.
Gastrointestinal Dark saliva, gastrointestinal bleeding, development of duodenal ulcer, anorexia, vomiting, diarrhea, constipation, dyspepsia, dry mouth, taste alterations. Hematologic Agranulocytosis, hemolytic and non-hemolytic anemia, thrombocytopenia, leukopenia. Hypersensitivity Angioedema, urticaria, pruritus, Henoch-Schönlein purpura, bullous lesions (including pemphigus-like reactions).
Musculoskeletal Back pain, shoulder pain, muscle cramps. Nervous System/Psychiatric Psychotic episodes including delusions, hallucinations, and paranoid ideation, bradykinetic episodes ("on-off" phenomenon), confusion, agitation, dizziness, somnolence, dream abnormalities including nightmares, insomnia, paresthesia, headache, depression with or without development of suicidal tendencies, dementia, pathological gambling, increased libido including hypersexuality, impulse control symptoms, seizures (including convulsions).
Respiratory Dyspnea, upper respiratory infection. Skin Rash, increased sweating, alopecia, dark sweat. Urogenital Urinary tract infection, urinary frequency, dark urine.
Laboratory Tests Decreased hemoglobin and hematocrit; abnormalities in alkaline phosphatase, SGOT (AST), SGPT (ALT), LDH, bilirubin, BUN, Coombs test; elevated serum glucose; white blood cells, bacteria, and blood in the urine. Other adverse reactions that have been reported with levodopa alone and with various carbidopa and levodopa formulations, and may occur with SINEMET are: Body as a Whole Abdominal pain and distress, fatigue. Cardiovascular Myocardial infarction.
Gastrointestinal Gastrointestinal pain, dysphagia, sialorrhea, flatulence, bruxism, burning sensation of the tongue, heartburn, hiccups. Metabolic Edema, weight gain, weight loss. Musculoskeletal Leg pain.
Nervous System/Psychiatric Ataxia, extrapyramidal disorder, falling, anxiety, gait abnormalities, nervousness, decreased mental acuity, memory impairment, disorientation, euphoria, blepharospasm (which may be taken as an early sign of excess dosage; consideration of dosage reduction may be made at this time), trismus, increased tremor, numbness, muscle twitching, activation of latent Horner's syndrome, peripheral neuropathy. Respiratory Pharyngeal pain, cough. Skin Malignant melanoma, flushing.
Special Senses Oculogyric crises, diplopia, blurred vision, dilated pupils. Urogenital Urinary retention, urinary incontinence, priapism. Miscellaneous Bizarre breathing patterns, faintness, hoarseness, malaise, hot flashes, sense of stimulation.
Laboratory Tests Decreased white blood cell count and serum potassium; increased serum creatinine and uric acid; protein and glucose in urine; decreased vitamin B 6 levels.
🔄 Drug Interactions ▾
Drug Interactions Caution should be exercised when the following drugs are administered concomitantly with SINEMET. Symptomatic postural hypotension occurred when SINEMET was added to the treatment of a patient receiving antihypertensive drugs. Therefore, when therapy with SINEMET 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 and levodopa may be associated with severe orthostatic hypotension not attributable to carbidopa and levodopa alone (see CONTRAINDICATIONS ). There have been rare reports of adverse reactions, including hypertension and dyskinesia, resulting from the concomitant use of tricyclic antidepressants and SINEMET.
Dopamine D 2 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 SINEMET should be carefully observed for loss of therapeutic response.
Use of SINEMET with dopamine-depleting agents (e.g., reserpine and tetrabenazine) or other drugs known to deplete monoamine stores is not recommended. SINEMET and iron salts or multivitamins containing iron salts should be coadministered with caution. Iron salts can form chelates with levodopa and carbidopa and consequently reduce the bioavailability of carbidopa and levodopa.
Although metoclopramide may increase the bioavailability of levodopa by increasing gastric emptying, metoclopramide may also adversely affect disease control by its dopamine receptor antagonistic properties.
🤰 Pregnancy ▾
Pregnancy No teratogenic effects were observed in a study in mice receiving up to 20 times the maximum recommended human dose of SINEMET. 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. SINEMET 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 SINEMET in women of childbearing potential requires that the anticipated benefits of the drug be weighed against possible hazards to mother and child.
🧒 Pediatric Use ▾
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.
🧓 Geriatric Use ▾
Geriatric Use In the clinical efficacy trials for SINEMET, almost half of the patients were older than 65, but few were older than 75. No overall meaningful differences in safety or effectiveness were observed between these subjects and younger subjects, but greater sensitivity of some older individuals to adverse drug reactions such as hallucinations cannot be ruled out. There is no specific dosing recommendation based upon clinical pharmacology data as SINEMET is titrated as tolerated for clinical effect.
🆘 Overdosage ▾
OVERDOSAGE Management of acute overdosage with SINEMET is the same as management of acute overdosage with levodopa. Pyridoxine is not effective in reversing the actions of SINEMET. 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 antiarrhythmic therapy should be given. The possibility that the patient may have taken other drugs as well as SINEMET 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.
🧬 Clinical Pharmacology ▾
CLINICAL PHARMACOLOGY Mechanism of Action Parkinson's disease is a progressive, neurodegenerative disorder of the extrapyramidal nervous system affecting the mobility and control of the skeletal muscular system. Its characteristic features include resting tremor, rigidity, and bradykinetic movements. Symptomatic treatments, such as levodopa therapies, may permit the patient better mobility.
Current evidence indicates that symptoms of Parkinson's disease are related to depletion of dopamine in the corpus striatum. Administration of dopamine is ineffective in the treatment of Parkinson's disease apparently because it does not cross the blood-brain barrier. However, levodopa, the metabolic precursor of dopamine, does cross the blood-brain barrier, and presumably is converted to dopamine in the brain.
This is thought to be the mechanism whereby levodopa relieves symptoms of Parkinson's disease. Pharmacodynamics When levodopa is administered orally, it is rapidly decarboxylated to dopamine in extracerebral tissues so that only a small portion of a given dose is transported unchanged to the central nervous system. For this reason, large doses of levodopa are required for adequate therapeutic effect, and these may often be accompanied by nausea and other adverse reactions, some of which are attributable to dopamine formed in extracerebral tissues.
Since levodopa competes with certain amino acids for transport across the gut wall, the absorption of levodopa may be impaired in some patients on a high protein diet. Carbidopa inhibits decarboxylation of peripheral levodopa. It does not cross the blood-brain barrier and does not affect the metabolism of levodopa within the central nervous system.
The incidence of levodopa-induced nausea and vomiting is less with SINEMET than with levodopa. In many patients, this reduction in nausea and vomiting will permit more rapid dosage titration. Since its decarboxylase inhibiting activity is limited to extracerebral tissues, administration of carbidopa with levodopa makes more levodopa available for transport to the brain.
Pharmacokinetics Carbidopa reduces the amount of levodopa required to produce a given response by about 75% and, when administered with levodopa, increases both plasma levels and the plasma half-life of levodopa, and decreases plasma and urinary dopamine and homovanillic acid. The plasma half-life of levodopa is about 50 minutes, without carbidopa. When carbidopa and levodopa are administered together, the half-life of levodopa is increased to about 1.5 hours.
At steady state, the bioavailability of carbidopa from SINEMET tablets is approximately 99% relative to the concomitant administration of carbidopa and levodopa. In clinical pharmacologic studies, simultaneous administration of carbidopa and levodopa produced greater urinary excretion of levodopa in proportion to the excretion of dopamine than administration of the two drugs at separate times. Pyridoxine hydrochloride (vitamin B 6 ), in oral doses of 10 mg to 25 mg, may reverse the effects of levodopa by increasing the rate of aromatic amino acid decarboxylation.
Carbidopa inhibits this action of pyridoxine; therefore, SINEMET can be given to patients receiving supplemental pyridoxine (vitamin B 6 ). Special Populations Geriatric: A study in eight young healthy subjects (21-22 yr) and eight elderly healthy subjects (69-76 yr) showed that the absolute bioavailability of levodopa was similar between young and elderly subjects following oral administration of levodopa and carbidopa. However, the systemic exposure (AUC) of levodopa was increased by 55% in elderly subjects compared to young subjects.
Based on another study in forty patients with Parkinson's disease, there was a correlation between age of patients and the increase of AUC of levodopa following administration of levodopa and an inhibitor of peripheral dopa decarboxylase. AUC of levodopa was increased by 28% in elderly patients (≥ 65 yr) compared to young patients (<…
🧬 Mechanism of Action ▾
Mechanism of Action Parkinson's disease is a progressive, neurodegenerative disorder of the extrapyramidal nervous system affecting the mobility and control of the skeletal muscular system. Its characteristic features include resting tremor, rigidity, and bradykinetic movements. Symptomatic treatments, such as levodopa therapies, may permit the patient better mobility.
Current evidence indicates that symptoms of Parkinson's disease are related to depletion of dopamine in the corpus striatum. Administration of dopamine is ineffective in the treatment of Parkinson's disease apparently because it does not cross the blood-brain barrier. However, levodopa, the metabolic precursor of dopamine, does cross the blood-brain barrier, and presumably is converted to dopamine in the brain.
This is thought to be the mechanism whereby levodopa relieves symptoms of Parkinson's disease.
📦 How Supplied / Storage and Handling ▾
HOW SUPPLIED SINEMET 25-100 Tablets are yellow oval tablets that are plain on one side, with “650” on the other. They are supplied as follows: NDC 78206-190-01 bottles of 100. SINEMET 10-100 Tablets are dark dapple-blue oval tablets that are plain on one side, with "647" and a score line on the other.
They are supplied as follows: NDC 78206-166-01 bottles of 100. SINEMET 25-250 Tablets are no longer marketed. Storage and Handling Store at 25°C (77°F), excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature].
Store in a tightly closed container, protected from light and moisture. Dispense in a tightly closed, light-resistant container.
📦 Storage and Handling ▾
Storage and Handling Store at 25°C (77°F), excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature]. Store in a tightly closed container, protected from light and moisture. Dispense in a tightly closed, light-resistant container.
📋 Description ▾
DESCRIPTION SINEMET ® (carbidopa and levodopa) is a combination of carbidopa and levodopa for the treatment of Parkinson's disease and syndrome. Carbidopa, an inhibitor of aromatic amino acid decarboxylation, is a white, crystalline compound, slightly soluble in water, with a molecular weight of 244.3. It is designated chemically as (—)-L-α-hydrazino-α-methyl-β-(3,4-dihydroxybenzene) propanoic acid monohydrate.
Its empirical formula is C 10 H 14 N 2 O 4 •H 2 O, and its structural formula is: Tablet content is expressed in terms of anhydrous carbidopa which has a molecular weight of 226.3. Levodopa, an aromatic amino acid, is a white, crystalline compound, slightly soluble in water, with a molecular weight of 197.2. It is designated chemically as (—)-L-α-amino-β-(3,4-dihydroxybenzene) propanoic acid.
Its empirical formula is C 9 H 11 NO 4 , and its structural formula is: SINEMET is supplied as tablets in two strengths: SINEMET 25-100, containing 25 mg of carbidopa and 100 mg of levodopa. SINEMET 10-100, containing 10 mg of carbidopa and 100 mg of levodopa. Inactive ingredients are microcrystalline cellulose, pregelatinized starch, starch (corn), and magnesium stearate.
SINEMET 10-100 Tablets also contain FD&C Blue #2. SINEMET 25-100 Tablets also contain D&C Yellow #10. SINEMET 25-250 Tablets are no longer marketed. image of carbidopa chemical structure image of levodopa chemical structure
💬 Information for Patients ▾
Information for Patients The patient should be informed that SINEMET is an immediate-release formulation of carbidopa and levodopa that is designed to begin release of ingredients within 30 minutes. It is important that SINEMET 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 and 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 SINEMET.
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 multivitamin 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 and levodopa therapy. Patients should be alerted to the possibility of sudden onset of sleep during daily activities, in some cases without awareness or warning signs, when they are taking dopaminergic agents, including levodopa.
Patients should be advised to exercise caution while driving or operating machinery and that if they have experienced somnolence and/or sudden sleep onset, they must refrain from these activities. (See WARNINGS, Falling Asleep During Activities of Daily Living and Somnolence .) There have been reports of patients experiencing intense urges to gamble, increased sexual urges, and other intense urges, and the inability to control these urges while taking one or more of the medications that increase central dopaminergic tone and that are generally used for the treatment of Parkinson's disease, including SINEMET.
Although it is not proven that the medications caused these events, these urges were reported to have stopped in some cases when the dose was reduced or the medication was stopped. Prescribers should ask patients about the development of new or increased gambling urges, sexual urges or other urges while being treated with SINEMET. Patients should inform their physician if they experience new or increased gambling urges, increased sexual urges, or other intense urges while taking SINEMET.
Physicians should consider dose reduction or stopping the medication if a patient develops such urges while taking SINEMET (see PRECAUTIONS, Impulse Control / Compulsive Behaviors ). Inform patients that vitamin B 6 deficiency may develop during treatment with carbidopa/levodopa therapies, including SINEMET. Tell patients to inform their healthcare provider if they develop symptoms such as depression, confusion, cheilosis, glossitis, dermatitis, anemia, neuropathy, and/or seizures (see WARNINGS, Vitamin B6 Deficiency and Seizures ).