Trade Names:Comtan- Tablets 200 mg
The exact mechanism of action is unknown. Inhibits catechol-O-methyltransferase (COMT), thus blocking the degradation of catechols, including dopamine and levodopa. This may lead to more sustained levels of dopamine and consequently a more prolonged antiparkinson effect.
Rapidly absorbed. T max is approximately 1 h. C max is approximately 1.2 mcg/mL (single 200 mg dose). Absolute bioavailability is 35%.
Vd is 20 L (IV). 98% is protein bound, mainly to albumin.
Almost completely metabolized; inactive metabolites formed by isomerization and glucuronidation.
Approximately 10% is excreted in the urine (0.2% as unchanged drug) and 90% in feces.
No important effects of renal function on the pharmacokinetics of entacapone have been demonstrated.Hepatic Function Impairment
AUC and C max are approximately 2-fold higher in those with a history of alcoholism and hepatic impairment.Elderly
Pharmacokinetics of entacapone are independent of age.Gender
No studies have been conducted.
As an adjunct to levodopa/carbidopa for the treatment of idiopathic Parkinson disease in patients who experience signs and symptoms of end-of-dose “wearing-off.”
PO 200 mg concomitantly with each levodopa/carbidopa dose; max, 8 times/day.
Store at 59° to 86°F.
May interfere with biliary excretion or metabolism of entacapone. Use with caution.Apomorphine, dobutamine, dopamine, epinephrine, isoproterenol, methyldopa, norepinephrine
Excessive changes in BP and increased heart rate, possibly arrhythmias, may occur. Use with caution. Closely monitor the clinical response of the patient.MAOIs
Because MAO and COMT are the 2 major enzyme systems involved in catecholamine metabolism, it is theoretically possible that the combination of entacapone and a nonselective MAOI (eg, phenelzine, tranylcypromine) could result in inhibition of the majority of the pathways responsible for normal catecholamine metabolism. Therefore, usually do not treat patients concomitantly with entacapone and a nonselective MAOI. However, entacapone may be coadministered with a selective MAOI-B (eg, selegiline).
None well documented.
Orthostatic hypotension (4%).
Dyskinesia (25%); hyperkinesia (10%); hypokinesia (9%); dizziness (8%); fatigue (6%); hallucinations (4%); anxiety, asthenia, somnolence (2%); agitation (1%).
Taste perversion (1%).
Nausea (14%); diarrhea (10%); abdominal pain (8%); constipation (6%); vomiting (4%); dry mouth (3%); dyspepsia, flatulence (2%); gastritis, GI disorders (1%).
Urine discoloration (10%).
Back pain (4%); sweating increased (2%); bacterial infection (1%).
Monitor patients closely if entacapone is discontinued. Monitor patients for melanoma frequently and on a regular basis.
Category C .
Safety and efficacy not established.
Use with caution.
May occur as early as the first week or as late as many months after initiating entacapone.
Exercise caution when discontinuing treatment. Withdrawal of entacapone should proceed slowly.
Entacapone may cause and/or exacerbate preexisting dyskinesia.
Cases of retroperitoneal fibrosis, pulmonary infiltrates, pleural effusion, and pleural thickening have been reported.
Rhabdomyolysis and a symptom complex resembling NMS reported in association with therapy. Exercise caution.
May increase the incidence of orthostatic hypotension associated with dopaminergic therapy.
Risk of melanoma is higher in patients with Parkinson disease compared with the general population; however, it has not been determined if this is caused by the disease or the treatment.
Abdominal pain, loose stools.
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