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Related to Comtan: Madopar, Sinemet, Exelon


Comtan, Comtess (UK)

Pharmacologic class: Catechol O-methyltransferase (COMT) inhibitor

Therapeutic class: Antidyskinetic

Pregnancy risk category C


Inhibits COMT, the primary enzyme involved in metabolizing levodopa. This inhibition increases levodopa blood level and duration of action, easing symptoms of Parkinson's disease.


Tablets: 200 mg

Indications and dosages

Adjunctive treatment of idiopathic Parkinson's disease in patients experiencing wearing off of carbidopa-levodopa effects

Adults: 200 mg P.O. with each carbidopa-levodopa dose, to a maximum of eight times daily (1,600 mg)


• Hypersensitivity to drug


Use cautiously in:

• hepatic or renal dysfunction, hypertension, heart disease

• pregnant and breastfeeding patients.


• Give without regard to food.

• Administer at same time as carbidopa-levodopa. Make sure patient swallows tablet whole.

Don't withdraw drug abruptly.

Adverse reactions

CNS: dizziness, depression, drowsiness, disorientation, memory loss, agitation, delusions, hallucinations, paranoia, euphoria, dyskinesia, hyperkinesia, light-headedness, paresthesia, heaviness of limbs, numbness of fingers

CV: tachycardia, orthostatic hypotension, hypertension

GI: nausea, vomiting, epigastric pain, flatulence

GU: urine discoloration

Respiratory: upper respiratory tract infection, dyspnea, sinus congestion

Other: fever


Drug-drug. Ampicillin, chloramphenicol, cholestyramine, erythromycin, probenecid, rifampin: decreased entacapone excretion

Bitolterol, dobutamine, dopamine, epinephrine, isoetherine, isoproterenol, methyldopa, norepinephrine: increased heart rate, increased risk of arrhythmias, excessive blood pressure changes

MAO inhibitors: increased risk of toxicity

Drug-behaviors. Alcohol use: increased risk of adverse reactions

Patient monitoring

• Monitor vital signs, watching especially for orthostatic hypotension.

• Evaluate neurologic status closely. Check for hallucinations and new onset or exacerbation of dyskinesia.

• Assess respiratory status, particularly for dyspnea and signs and symptoms of upper respiratory tract infection.

• Monitor nutritional and hydration status if patient experiences vomiting.

Patient teaching

• Instruct patient to swallow tablet whole and to take it at same time as carbidopa-levodopa.

Caution patient not to stop taking drug abruptly.

• Advise patient to move slowly when sitting up or standing, to avoid dizziness or light-headedness from sudden blood pressure decrease.

• Caution patient to avoid driving and other hazardous activities until drug no longer affects concentration and alertness.

Instruct patient (and caregiver) to institute safety measures at home to prevent injury related to disease or drug's adverse CNS effects.

• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs and behaviors mentioned above.

McGraw-Hill Nurse's Drug Handbook, 7th Ed. Copyright © 2013 by The McGraw-Hill Companies, Inc. All rights reserved


(en-tak-a-pone) ,


(trade name)


Therapeutic: antiparkinson agents
Pharmacologic: catechol o methyltransferase inhibitors
Pregnancy Category: C


With levodopa/carbidopa to treat idiopathic Parkinson’s disease when signs and symptoms of end-of-dose "wearing-off" (so-called fluctuating patients) occur.


Acts as a selective and reversible inhibitor of the enzyme catechol O-methyltransferase (COMT).
Inhibition of this enzyme prevents the breakdown of levodopa, increasing availability to the CNS.

Therapeutic effects

Prolongs duration of response to levodopa with end-of-dose motor fluctuations.
Decreased signs and symptoms of Parkinson’s disease.


Absorption: 35% absorbed following oral administration; absorption is rapid.
Distribution: Unknown.
Protein Binding: 98%.
Metabolism and Excretion: Minimal amounts excreted unchanged; highly metabolized followed by biliary excretion.
Half-life: Initial phase—0.4–0.7 hr; second phase—2.4 hr.

Time/action profile (inhibition of COMT)

POunknownunknownup to 8 hr


Contraindicated in: Hypersensitivity;Concurrent nonselective MAO inhibitor therapy.
Use Cautiously in: Hepatic impairment;Concurrent use of drugs that are metabolized by COMT; Obstetric / Lactation: Safety not established; Pediatric: No identified use in children.

Adverse Reactions/Side Effects

Central nervous system

  • neuroleptic malignant syndrome (life-threatening)
  • dizziness
  • hallucinations
  • syncope
  • urges (gambling, sexual)


  • pulmonary infiltrates
  • pleural effusion
  • pleural thickening


  • hypotension


  • melanoma


  • abdominal pain
  • colitis
  • diarrhea
  • nausea (during initiation)
  • retroperitoneal fibrosis


  • brownish-orange discoloration of urine


  • rhabdomyolysis (life-threatening)


  • dyskinesia


Drug-Drug interaction

Concurrent use with selective MAO inhibitors is not recommended; both agents inhibit the metabolic pathways of catecholamines.Concurrent use of drugs that are metabolized by COMT such as isoproterenol, epinephrine, norepinephrine, dopamine, dobutamine, and methyldopa may ↑ risk of tachycardia, ↑ BP, and arrhythmias.Probenecid, cholestyramine, erythromycin, rifampin, ampicillin, and chloramphenicol may interfere with biliary elimination of entacapone; use concurrently with caution.


Oral (Adults) 200 mg with each dose of levodopa/carbidopa up to a maximum of 8 times daily.

Availability (generic available)

Tablets: 200 mg
In combination with: levodopa/carbidopa (Stalevo), see combination drugs.

Nursing implications

Nursing assessment

  • Assess parkinsonian and extrapyramidal symptoms (restlessness or desire to keep moving, rigidity, tremors, pill rolling, mask-like face, shuffling gait, muscle spasms, twisting motions, difficulty speaking or swallowing, loss of balance control) prior to and during therapy. Dyskinesia may increase with therapy.
  • Monitor patient for development of diarrhea. Usually occurs within 4 to 12 wk of start of therapy, but may occur as early as the first week and as late as months after initiation of therapy.
  • Monitor patient for signs similar to neuroleptic malignant syndrome (elevated temperature, muscular rigidity, altered consciousness, elevated CPK). Symptoms have been associated with rapid dose reduction or withdrawal of other dopaminergic drugs. Withdrawal should be gradual.

Potential Nursing Diagnoses

Impaired physical mobility (Indications)
Risk for injury (Indications)


  • Oral: Always administer entacapone with levodopa/carbidopa. Entacapone has no antiparkinsonism effects of its own.

Patient/Family Teaching

  • Encourage patient to take entacapone as directed. Take missed doses as soon as possible, up to 2 hr before the next dose. Taper gradually when discontinuing or a withdrawal reaction may occur.
  • May cause dizziness or hallucinations. Advise patient to avoid driving or other activities that require alertness until response to the drug is known.
  • Inform patient that nausea may occur, especially at initiation of therapy and diarrhea. Advise patient with diarrhea to drink fluids to maintain adequate hydration and monitor for weight loss. If diarrhea is prolonged, may resolve with discontinuation. Therapy may cause change in urine color to brownish orange.
  • Caution patient to change positions slowly to minimize orthostatic hypotension.
  • Advise patient to notify health care professional if suspicious or unusual skin changes, hallucinations, or new or increased gambling, sexual, or other intense urges occur.
  • Instruct patient to notify health care professional if pregnancy is planned or suspected, or if breast feeding.
  • Emphasize the importance of routine follow-up exams.

Evaluation/Desired Outcomes

  • Decreased signs and symptoms of Parkinson’s disease.
Drug Guide, © 2015 Farlex and Partners


A nitrocatechol-class COMT (catechol-O-methyltransferase) inhibitor used to improve motor performance in Parkinson patients receiving l-DOPA/carbidopa.

Adverse effects
Dyskinesia, which often resolves with ongoing therapy; diarrhoea, nausea and abdominal pain; asymptomatic red-brown urine.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.


Entacapone Neurology A COMT inhibitor which may improve motor performance in Parkinson Pts receiving levodopa/carbidopa. See Parkinson's disease.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
For now, the agency is recommending that patients do not stop taking Stalevo or Comtan unless they're advised to do so by their health care provider, and that health care professionals "should regularly evaluate the status of patients who are taking Stalevo, especially if they have a history of cardiovascular disease."
The Indian company has also been allowed to market other strengths of Stalevo from 2 October 2012 and generic versions of Comtan from 1 April 2013, unless certain conditions relating to launch are fulfilled even earlier.
"Although we have demonstrated in the lab that Comtan is active against M.tuberculosis, additional studies are required in order to transform it into an anti-tubercular therapeutic," said Sarah L.
Entacapone (Comtan), given with Sinemet, inactivates an enzyme responsible for breaking down the levodopa component before it can reach the target, potentially enhancing and prolonging the dopamine effect.
Entacapone, a COMT enzyme inhibitor used in the treatment of Parkinson's disease, is Orion Pharma's patented molecule discovery, available globally as Comtess and Comtan. In June 2003, Orion Pharma received the Marketing Authorization from FDA for Stalevo, a new treatment of PD, which combines levodopa and carbidopa with entacapone in one tablet.
Speciality pharmaceutical company Sun Pharmaceutical Industries Ltd (NSE: SUNPHARMA) (BSE: 524715) today announced the settlement of litigation with Orion Corporation (Korea: 001800) over generic Stalevo and Comtan.
Sales of the company's Parkinson's disease drugs Stalevo and Comtan went up by 15.3% to EUR492m.
The stolen pills included 1.64m of Comtan, used to treat Parkinson's disease, 489,000 of Lopressor, which helps fight heart disease by lowering blood pressure, and 329,000 Femara breast cancer tablets.
Catechol-0-methyltransferase Prevents peripheral breakdown of inhibitors (COMT) levodopa; used to extend benefit Entacapone (Comtan) of levodopa doses and reduce wearing off reactions.
entacapone 200 mg with $8.40 (five (Comtan) each dose of times a day) levodopa tolcapone 100-200 $7.29 (Tasmar) mg t.i.d (100 mg t.i.d) MONOAMINE OXIDASE TYPE B INHIBITOR selegiline 5 mg once or $3.88 twice daily (5 mg b.i.d.) Drug Comment ** DOPAMINE PRECURSOR carbidopa/levodopa Decreases the amount of levodopa needed and lessens some side effects.