Entacapone¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ The mechanism of action of entacapone is believed to be through its ability to inhibit COMT and alter the plasma pharmacokinetics of levodopa. When entacapone is given in conjunction with levodopa and an aromatic amino acid decarboxylase inhibitor, such as carbidopa, plasma levels of levodopa are greater and more sustained than after administration of levodopa and an aromatic amino acid decarboxylase inhibitor alone. It is believed that at a given frequency of levodopa administration, these more sustained plasma levels of levodopa result in more constant dopaminergic stimulation in the brain, leading to greater effects on the signs and symptoms of Parkinson's disease.
Pharmacology
Entacapone¿¡ ´ëÇÑ Pharmacology Á¤º¸ Entacapone is used in the treatment of Parkinson¡¯s disease as an adjunct to levodopa/carbidopa therapy. Entacapone is a selective and reversible inhibitor of catechol-O-methyltransferase (COMT). In mammals, COMT is distributed throughout various organs with the highest activities in the liver and kidney. COMT also occurs in the heart, lung, smooth and skeletal muscles, intestinal tract, reproductive organs, various glands, adipose tissue, skin, blood cells and neuronal tissues, especially in glial cells. COMT catalyzes the transfer of the methyl group of S-adenosyl-L-methionine to the phenolic group of substrates that contain a catechol structure. Physiological substrates of COMT include dopa, catecholamines (dopamine, norepinephrine, and epinephrine) and their hydroxylated metabolites. The function of COMT is the elimination of biologically active catechols and some other hydroxylated metabolites. In the presence of a decarboxylase inhibitor, COMT becomes the major metabolizing enzyme for levodopa, catalyzing the metabolism to 3-methoxy-4-hydroxy-L-phenylalanine (3-OMD) in the brain and periphery.
Protein Binding
Entacapone¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ 98% (bind to serum albumin)
Half-life
Entacapone¿¡ ´ëÇÑ ¹Ý°¨±â Á¤º¸ 0.4-0.7 hour
Absorption
Entacapone¿¡ ´ëÇÑ Absorption Á¤º¸ Entacapone is rapidly absorbed (approximately 1 hour). The absolute bioavailability following oral administration is 35%.
Entacapone¿¡ ´ëÇÑ Biotransformation Á¤º¸ Metabolized via isomerization to the cis-isomer, followed by direct glucuronidation of the parent and cis-isomer.
Toxicity
Entacapone¿¡ ´ëÇÑ Toxicity Á¤º¸ Side effect include increase the occurrence of orthostatic hypotension, severe rhabdomyolysis, dyskinesia, hallucinations, hyperkinesia, hypokinesia, dizziness, fatigu,e gastrointestinal effects including abdominal pain constipation diarrhea nausea
Drug Interactions
Entacapone¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Apomorphine Entacapone increases the effect and toxicity of sympathomimeticsBitolterol Entacapone increases the effect and toxicity of sympathomimeticsDobutamine Entacapone increases the effect and toxicity of sympathomimeticsDopamine Entacapone increases the effect and toxicity of sympathomimeticsEpinephrine Entacapone increases the effect and toxicity of sympathomimeticsIsocarboxazid Possible hypertensive crisis with this combinationIsoetharine Entacapone increases the effect and toxicity of sympathomimeticsIsoproterenol Entacapone increases the effect and toxicity of sympathomimeticsMethyldopa Entacapone increases the effect and toxicity of sympathomimeticsNorepinephrine Entacapone increases the effect and toxicity of sympathomimeticsPhenelzine Possible hypertensive crisis with this combinationTranylcypromine Possible hypertensive crisis with this combinationBitolterol Entacapone increases the effect and toxicity of sympathomimetics
Description
Entacapone¿¡ ´ëÇÑ Description Á¤º¸ Entacapone is a catechol-O-methyl transferase inhibitor for the treatment of Parkinson's disease. When administered in conjunction with dopaminergic agents such as L-DOPA, entacapone increases the bioavailability of these compounds by facilitating their passage across the blood-brain barrier.It is a member of the class of nitrocatechols.The most frequent undesirable effects caused by entacapone relate to the increased effects of L-DOPA, such as involuntary movements (dyskinesias).These occur most frequently at the beginning of entacapone treatment. Others common side effects are gastrointestinal problems, including diarrhoea, nausea and abdominal pains. The substance may cause urine to turn reddish-brown. This is a harmless side effect and is not a cause for concern. In studies with entacapone, some people have reported experiencing a dry mouth.
Dosage Form
Entacapone¿¡ ´ëÇÑ Dosage_Form Á¤º¸ Tablet Oral
Drug Category
Entacapone¿¡ ´ëÇÑ Drug_Category Á¤º¸ AntidyskineticsAntiparkinson AgentsCentral Nervous System AgentsEnzyme Inhibitors