entacapone · by orion pharma
Entacapone tablets USP is available as tablets containing 200 mg entacapone. Entacapone is an inhibitor of catechol- O -methyltransferase (COMT), used in the treatment of Parkinson's disease as an adjunct to levodopa and carbidopa therapy. It is a nitrocatechol-structured compound with a relative molecular mass of 305.29. The chemical name of entacapone is (E)-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)-N,N-diethyl-2-propenamide. Its empirical formula is C 14 H 15 N 3 O 5 and its structural formula is: The inactive ingredients of the entacapone tablets USP are microcrystalline cellulose, mannitol, sodium starch glycolate, povidone, magnesium stearate, polyvinyl alcohol- partly hydrolyzed, talc, macrogol, lecithin (soya), iron oxide yellow, iron oxide red, and titanium dioxide. Chemical Structure
The recommended dose of entacapone is one 200 mg tablet administered concomitantly with each levodopa and carbidopa dose to a maximum of 8 times daily (200 mg × 8 = 1,600 mg per day). Clinical experience with daily doses above 1,600 mg is limited. Entacapone should always be administered in association with levodopa and carbidopa. Entacapone has no antiparkinsonian effect of its own. In clinical studies, the majority of patients required a decrease in daily levodopa dose if their daily dose of levodopa had been greater than or equal to 800 mg or if patients had moderate or severe dyskinesia before beginning treatment. To optimize an individual patient's response, reductions in daily levodopa dose or extending the interval between doses may be necessary. In clinical studies, the average reduction in daily levodopa dose was about 25% in those patients requiring a levodopa dose reduction. (More than 58% of patients with levodopa doses above 800 mg daily required such a reduction.) Entacapone can be combined with both the immediate and sustained-release formulations of levodopa and carbidopa. Entacapone may be taken with or without food (see CLINICAL PHARMACOLOGY ). Patients With Impaired Hepatic Function Patients with hepatic impairment should be treated with caution. The AUC and C max of entacapone approximately doubled in patients with documented liver disease, compared to…
Because clinical studies are conducted under widely varying conditions, the incidence of adverse reactions (number of unique patients experiencing an adverse reaction associated with treatment per total number of patients treated) observed in the clinical studies of a drug cannot be directly compared to the incidence of adverse reactions in the clinical studies of another drug and may not reflect the incidence of adverse reactions observed in practice. A total of 1,450 patients with Parkinson's disease were treated with entacapone in premarketing clinical studies. Included were patients with fluctuating symptoms, as well as those with stable responses to levodopa therapy. All patients received concomitant treatment with levodopa preparations, however, and were similar in other clinical aspects. The most commonly observed adverse reactions (incidence at least 3% greater than placebo) in double-blind, placebo-controlled studies (N=1,003) associated with the use of entacapone were: dyskinesia, urine discoloration, diarrhea, nausea, hyperkinesia, abdominal pain, vomiting, and dry mouth. Approximately 14% of the 603 patients given entacapone in the double-blind, placebo-controlled studies discontinued treatment due to adverse reactions, compared to 9% of the 400 patients who received placebo. The most frequent causes of discontinuation in decreasing order were: psychiatric…
Important safety information
Monoamine oxidase (MAO) and COMT are the two major enzyme systems involved in the metabolism of catecholamines. It is theoretically possible, therefore, that the combination of entacapone and a non-selective MAO inhibitor (e.g., phenelzine and tranylcypromine) would result in inhibition of the majority of the pathways responsible for normal catecholamine metabolism. For this reason, patients should ordinarily not be treated concomitantly with entacapone and a non-selective MAO inhibitor. Entacapone can be taken concomitantly with a selective MAO-B inhibitor (e.g., selegiline). Drugs Metabolized By Catechol-O-Methyltransferase (COMT) When a single 400 mg dose of entacapone was given with intravenous isoprenaline (isoproterenol) and epinephrine without coadministered levodopa and dopa decarboxylase inhibitor, the overall mean maximal changes in heart rate during infusion were about 50% and 80% higher than with placebo, for isoprenaline and epinephrine, respectively. Therefore, 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, possible arrhythmias, and excessive changes…
Drug Interactions See PRECAUTIONS, Drug Interactions . Drug Interactions In vitro studies of human CYP enzymes showed that entacapone inhibited the CYP enzymes 1A2, 2A6, 2C9, 2C19, 2D6, 2E1 and 3A only at very high concentrations (IC50 from 200 microM to over 1,000 microM; an oral 200 mg dose achieves a highest level of approximately 5 microM in people); these enzymes would therefore not be expected to be inhibited in clinical use. In an interaction study in healthy volunteers, entacapone did not significantly change the plasma levels of S-warfarin while the AUC for R-warfarin increased on average by 18% [Cl90 11% to 26%], and the INR values increased on average by 13% [Cl90 6% to 19%]. Nevertheless, cases of significantly increased INR in patients concomitantly using warfarin have been reported during the postapproval use of entacapone. Therefore, monitoring of INR is recommended when entacapone treatment is initiated or when the dose is increased for patients receiving warfarin.
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Clinical content sourced from the FDA label via openFDA (U.S. FDA). Provided for general reference only — not medical advice. Always consult a licensed professional and the current prescribing information.
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