Carbidopa, levodopa, and entacapone
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From MedlinePlus, U.S. National Library of Medicine
Aromatic Amino Acid Decarboxylation Inhibitor, Aromatic Amino Acid, Catechol-O-Methyltransferase Inhibitor
Dosing in kidney impairment
Renal Impairment Renal impairment does not affect pharmacokinetics of entacapone. There are no studies on the pharmacokinetics of levodopa and carbidopa in patients with renal impairment [see Clinical Pharmacology ].
Dosing in liver impairment
Hepatic Impairment or Biliary Obstruction There are no studies on the pharmacokinetics of carbidopa and levodopa in patients with hepatic impairment. Carbidopa, levodopa and entacapone tablets should be administered cautiously to patients with biliary obstruction or hepatic disease since biliary excretion appears to be the major route of excretion of entacapone and hepatic impairment had a significant effect on the pharmacokinetics of entacapone when 200 mg entacapone was administered alone [see Clinical Pharmacology ].
Preparation and administration
Important Administration Instructions Do not split, crush or chew carbidopa, levodopa and entacapone tablets. Administer only one tablet at each dosing interval. All strengths of carbidopa, levodopa and entacapone tablets contain 200 mg of entacapone. Combining multiple tablets or portions of tablets to achieve a higher levodopa dose may lead to an overdose of entacapone.
Administer carbidopa, levodopa and entacapone tablets with or without food. However, a high-fat, high-calorie meal may delay the absorption of levodopa by about 2 hours [see Clinical Pharmacology ].
Drug interactions
Check carbidopa, levodopa, and entacapone against a medication listLabel text (12 paragraphs)
7 DRUG INTERACTIONS • Drugs metabolized by COMT: use with caution ( 5.11 , 7.2 ) • Anti-hypertensive agents: dose adjustment may be required ( 7.3 ) • Tricyclic antidepressants: risk of hypertension and dyskinesia reported during concomitant use with carbidopa/levodopa ( 7.4 ) • Dopamine D2 receptor antagonists, isoniazid, phenytoin, papaverine and iron salts: may reduce efficacy of carbidopa, levodopa and entacapone tablets ( 7.5 , 7.6 , 7.7 , 7.8 , 7.9 ) • Drugs that interfere with biliary excretion, glucuronidation and intestinal beta-glucuronidase: dose adjustment of carbidopa, levodopa and entacapone tablets may be required ( 7.10 ) • Drugs metabolized by CYP2C9 (e.g., coumadin): dose adjustment of carbidopa, levodopa and entacapone tablets may be required; monitor INR when initiating carbidopa, levodopa and entacapone tablets in patients on coumadin ( 7.11 )
7.1 MAO Inhibitors Patients receiving nonselective MAO inhibitors and carbidopa, levodopa and entacapone may be at risk of increased adrenergic tone. Therefore, the use of carbidopa, levodopa and entacapone tablets is contraindicated in patients receiving nonselective MAO inhibitors [see Contraindications (4) ].
7.2 Drugs Metabolized by Catechol-O-Methyltransferase (COMT) Drugs known to be metabolized by COMT, such as isoproterenol, epinephrine, norepinephrine, dopamine, dobutamine, alpha-methyldopa, apomorphine, isoetherine, and bitolterol should be administered with caution in patients receiving entacapone regardless of the route of administration (including inhalation), as their interaction may result in increased heart rates, possibly arrhythmias, and excessive changes in blood pressure [see Warnings and Precautions (5.11) ].
7.3 Antihypertensive Agents Symptomatic postural hypotension has occurred when carbidopa/levodopa was added to the treatment of patients receiving antihypertensive drugs. When starting therapy with carbidopa, levodopa and entacapone tablets, dosage adjustment of antihypertensive drug may be required.
7.4 Tricyclic Antidepressants There have been reports of adverse reactions, including hypertension and dyskinesia, resulting from the concomitant use of tricyclic antidepressants and carbidopa/levodopa.
7.5 Dopamine D2 Receptor Antagonists Dopamine D2 receptor antagonists (e.g., metoclopramide, phenothiazines, butyrophenones, risperidone) may reduce the therapeutic effects of levodopa.
7.6 Isoniazid Isoniazid may reduce the therapeutic effects of levodopa, a dose increase may be necessary.
7.7 Phenytoin The beneficial effects of levodopa in Parkinson's disease have been reported to be reversed by phenytoin. Patients taking phenytoin with carbidopa/levodopa should be carefully observed for loss of therapeutic response. Carbidopa, levodopa and entacapone tablets dosage should be increased as clinically needed in patients receiving phenytoin.
7.8 Papaverine The beneficial effects of levodopa in Parkinson's disease have been reported to be reversed by papaverine. Patients taking papaverine with carbidopa/levodopa should be carefully observed for loss of therapeutic response. Carbidopa, levodopa and entacapone tablets dosage should be increased as clinically needed in patients receiving papaverine.
7.9 Iron Salts Iron salts or multi vitamins containing iron salts should be coadministered with caution. Iron salts can form chelates with levodopa, carbidopa and entacapone and consequently reduce bioavailability of levodopa, carbidopa and entacapone.
7.10 Drugs Known to Interfere with Biliary Excretion, Glucuronidation, and Intestinal Beta-glucuronidase As most entacapone excretion is via the bile, caution should be exercised when drugs known to interfere with biliary excretion, glucuronidation, and intestinal beta-glucuronidase are given concurrently with entacapone. These include probenecid, cholestyramine, and some antibiotics (e.g., erythromycin, rifampicin, ampicillin and chloramphenicol).
7.11 Drugs Metabolized via CYP2C9 (e.g., coumadin) The dosage of carbidopa, levodopa and entacapone tablets should be adjusted as clinically needed in patients using other drugs metabolized via CYP2C9. An interaction study in healthy volunteers, entacapone increased the AUC of R-warfarin on average by 18%, and the INR values on average by 13%. Cases of increased INR in patients concomitantly using warfarin have been reported during the post-approval use of entacapone. Thus, monitoring of INR is recommended when carbidopa, levodopa and entacapone tablets treatment is initiated for patients receiving warfarin.
Supplement interactions
Dietary supplement interactions
1 noted- Some evidence indicates that in healthy people, iron supplements reduce the absorption of levodopa (found in Sinemet and Stalevo), used to treat Parkinson’s disease and restless leg syndrome, possibly through chelation. In the United States, the labels for levodopa warn that iron-containing dietary supplements might reduce the amount of levodopa available to the body and, thus, diminish its clinical effectiveness.
Contraindications
Carbidopa, levodopa and entacapone tablets are contraindicated in patients: • Taking nonselective monoamine oxidase (MAO) inhibitors (e.g., phenelzine and tranylcypromine). These nonselective MAO inhibitors must be discontinued at least two weeks prior to initiating therapy with carbidopa, levodopa and entacapone tablets. • With narrow-angle glaucoma. • Concomitant use of nonselective monoamine oxidase (MAO) inhibitors ( 4 ) • Narrow-angle glaucoma ( 4 )
Safety data
Reported adverse events (FAERS)
Liver injury (LiverTox)
LiverTox has no chapter for carbidopa, levodopa, and entacapone. Check the label's hepatic warnings.
Pregnancy and lactation
Pregnancy
8.1 Pregnancy Risk Summary There are no adequate data on the developmental risk associated with the use of carbidopa, levodopa and entacapone tablets in pregnant women. In animals, administration of carbidopa-levodopa or entacapone during pregnancy was associated with developmental toxicity, including increased incidences of fetal malformations ( see Data ). The estimated background risk of major birth defects and miscarriage in the indicated population is unknown. In the U.S. general population, the estimated background risks of major birth defects and miscarriage in clinically recognized pregnancies are 2 to 4% and 15 to 20%, respectively.
Data Animal data In nonclinical studies in which carbidopa-levodopa was administered to pregnant animals, increased incidences of visceral and skeletal malformations were observed in rabbits at all doses and ratios of carbidopa-levodopa tested, which ranged from 10 times (carbidopa)-5 times (levodopa) to 20 times (carbidopa)-10 times (levodopa) the maximum recommended human dose (MRHD) of 1,600 mg/day. In rats, there was a decrease in the number of live pups delivered by dams receiving approximately two times (carbidopa)-five times (levodopa) the MRHD throughout organogenesis.
No effects on malformation frequencies were observed in mice receiving up to 20 times the MRHD of carbidopa-levodopa. In embryo-fetal development studies of entacapone, pregnant animals received doses of up to 1,000 mg/kg/day (rats) or 300 mg/kg/day (rabbits) throughout organogenesis. Increased incidences of fetal variations were evident in litters from rats treated with the highest dose, in the absence of overt signs of maternal toxicity. The maternal plasma entacapone exposure (AUC) associated with this dose was approximately 34 times that in humans at the MRHD.
Increased frequencies of abortions and late/total resorptions and decreased fetal weights were observed in the litters of rabbits treated with maternally toxic doses of 100 mg/kg/day (plasma AUCs less than that in humans at the MRHD) or greater. There were no increases in malformation rates in these studies. When entacapone was administered to female rats prior to mating and during early gestation, an increased incidence of fetal eye anomalies (macrophthalmia, microphthalmia, anophthalmia) was observed in the litters of dams treated with doses of 160 mg/kg/day (plasma AUCs seven times that in humans at the MRHD) or greater, in the absence of maternal toxicity.
Administration of up to 700 mg/kg/day (plasma AUCs 28 times that in humans at the MRHD) to rats during the latter part of…
For breastfeeding, also see LactMed (National Library of Medicine), which summarizes milk levels and infant effects.
Supply and cost
Drug shortage status
Recalls (last 24 months)
Therapeutic equivalence (Orange Book)
Price ladder
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