Comtan
entacapone
Pharmacologic class: Catechol O-methyltransferase (COMT) inhibitor
Therapeutic class: Antidyskinetic
Pregnancy risk category C
Action
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.
Availability
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)
Contraindications
• Hypersensitivity to drug
Precautions
Use cautiously in:
• hepatic or renal dysfunction, hypertension, heart disease
• pregnant and breastfeeding patients.
Administration
• Give without regard to food.
• Administer at same time as carbidopa-levodopa. Make sure patient swallows tablet whole.
See 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
Interactions
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.
See 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.
See 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.
entacapone
(en-tak-a-pone) entacapone,Comtan
(trade name)Classification
Therapeutic: antiparkinson agentsPharmacologic: catechol o methyltransferase inhibitors
Indications
Action
Therapeutic effects
Pharmacokinetics
Time/action profile (inhibition of COMT)
| ROUTE | ONSET | PEAK | DURATION |
|---|---|---|---|
| PO | unknown | unknown | up to 8 hr |
Contraindications/Precautions
Adverse Reactions/Side Effects
Central nervous system
- neuroleptic malignant syndrome (life-threatening)
- dizziness
- hallucinations
- syncope
- urges (gambling, sexual)
Respiratory
- pulmonary infiltrates
- pleural effusion
- pleural thickening
Cardiovascular
- hypotension
Dermatologic
- melanoma
Gastrointestinal
- abdominal pain
- colitis
- diarrhea
- nausea (during initiation)
- retroperitoneal fibrosis
Genitourinary
- brownish-orange discoloration of urine
Musculoskeletal
- rhabdomyolysis (life-threatening)
Neurologic
- dyskinesia
Interactions
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.Route/Dosage
Availability (generic available)
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)
Implementation
- 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.
entacapone
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.