Entacapone

Generic name: entacapone
Brand name: Comtan
Dosage form: oral tablet (200 mg)
Drug class: Dopaminergic antiparkinsonism agents

Medically reviewed by A Ras MD.

What is entacapone?

Entacapone is a prescription medicine that is used to treat Parkinson’s disease.

Description

arbidopa, levodopa and entacapone tablets is a combination of carbidopa, levodopa, and entacapone for the treatment of Parkinson’s disease.

Carbidopa, an inhibitor of aromatic amino acid decarboxylation, is a white, crystalline compound, slightly soluble in water, with a molecular weight of 244.3. It is designated chemically as (-)-L-(α-hydrazino-(α-methyl-β-(3,4-dihydroxybenzene) propanoic acid monohydrate. Its empirical formula is C10H14N2O4•H2O, and its structural formula is:

Tablet content is expressed in terms of anhydrous carbidopa, which has a molecular weight of 226.3.

Levodopa, an aromatic amino acid, is a white, crystalline compound, slightly soluble in water, with a molecular weight of 197.2. It is designated chemically as (-)-L-α-amino-β-(3,4-dihydroxybenzene) propanoic acid. Its empirical formula is C9H11NO4, and its structural formula is:

Entacapone, a COMT inhibitor, is a nitro-catechol-structured compound with a molecular weight of 305.3. The chemical name of entacapone is (E)-2-cyano-3-(3,4-dihydroxy-5-nitrophenyl)-N,N-diethyl-2-propenamide. Its empirical formula is C14H15N3O5 and its structural formula is:

Inactive Ingredients: corn starch, microcrystalline cellulose, croscarmellose sodium, glycerol 85%, hypromellose, magnesium stearate, mannitol, polysorbate 80, povidone, sucrose, red iron oxide, and titanium dioxide. Tablets containing 12.5 mg of carbidopa, 50 mg of levodopa and 200 mg of entacapone, tablets containing 25 mg of carbidopa, 100 mg of levodopa and 200 mg of entacapone and tablets containing 37.5 mg of carbidopa, 150 mg of levodopa and 200 mg of entacapone also contain yellow iron oxide.

Mechanism of Action

Levodopa

Current evidence indicates that symptoms of Parkinson’s disease are related to depletion of dopamine in the corpus striatum. Administration of dopamine is ineffective in the treatment of Parkinson’s disease because it does not cross the blood-brain barrier. However, levodopa the metabolic precursor of dopamine, does cross the blood-brain barrier, and is presumably converted to dopamine in the brain. This is thought to be the mechanism whereby levodopa relieves the symptoms of Parkinson’s disease.

Carbidopa

When levodopa is administered orally, it is rapidly decarboxylated to dopamine in extracerebral tissues so that only a small portion of a given dose is transported unchanged to the central nervous system. Carbidopa inhibits the decarboxylation of peripheral levodopa, making more levodopa available for delivery to the brain.

Entacapone

Entacapone is a selective and reversible inhibitor of catechol-O-methyltransferase (COMT).

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. When decarboxylation of levodopa is prevented by carbidopa, COMT becomes the major metabolizing enzyme for levodopa, catalyzing its metabolism to 3-methoxy-4-hydroxy-L-phenylalanine (3-OMD).

Before taking entacapone, tell your doctor:

If you are allergic to entacapone; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.

This medicine may interact with other drugs or health problems.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take entacapone with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take entacapone?

Tell all of your health care providers that you take entacapone. This includes your doctors, nurses, pharmacists, and dentists.
Avoid driving and doing other tasks or actions that call for you to be alert until you see how entacapone affects you.
To lower the chance of feeling dizzy or passing out, rise slowly if you have been sitting or lying down. Be careful going up and down stairs.
Talk with your doctor before you drink alcohol or use other drugs and natural products that slow your actions.
Have blood work checked as you have been told by the doctor. Talk with the doctor.
This medicine may change the color of urine to brown or orange. This is normal and not harmful.
The chance of a type of skin cancer called melanoma may be raised in people with Parkinson’s disease. It is not known if entacapone may also raise the chance. Have skin exams while you take entacapone. Talk with your doctor.
Do not stop taking entacapone all of a sudden without calling your doctor. You may have a greater risk of side effects. If you need to stop entacapone, you will want to slowly stop it as ordered by your doctor.
It is common to have diarrhea with entacapone. Sometimes, diarrhea has been very bad and rarely has led to needing to go to the hospital. Very bad diarrhea may lead to weight loss, dehydration, or low potassium levels. Talk with your doctor.
If you get diarrhea, you will need to make sure to avoid getting dehydrated. Drink plenty of fluids and watch for weight loss. Talk with your doctor.
Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using entacapone while you are pregnant.
Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

How is entacapone best taken?

Use entacapone as ordered by your doctor. Read all information given to you. Follow all instructions closely.

Keep taking entacapone as you have been told by your doctor or other health care provider, even if you feel well.
Take with or without food.
Drink lots of noncaffeine liquids unless told to drink less liquid by your doctor.

What do I do if I miss a dose?

Take a missed dose as soon as you think about it.
If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
Do not take 2 doses at the same time or extra doses.

What are the side effects of entacapone that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
Severe diarrhea.
Diarrhea that will not go away.
Very bad belly pain.
Very bad dizziness or passing out.
Muscle pain or weakness.
Muscle stiffness.
Feeling confused.
Fever.
Strong urges that are hard to control (such as eating, gambling, sex, or spending money).
Trouble controlling body movements that is new or worse.
Shortness of breath.
Hallucinations (seeing or hearing things that are not there).
Mood changes.
Change in the way you act.
A skin lump or growth.
Change in color or size of a mole.
Some people have fallen asleep during activities like driving, eating, or talking. Some people did not feel sleepy and felt alert right before falling asleep. This has happened up to 1 year after entacapone was started. If you fall asleep during activities, do not drive or do other tasks or actions that call for you to be alert while you take entacapone. Call your doctor right away if this happens or you feel very sleepy.
If you are having diarrhea, call your doctor right away if you have signs of dehydration like dry skin, dry mouth, dry eyes, thirst, fast heartbeat, dizziness, fast breathing, or confusion; signs of low potassium levels like muscle pain or weakness, muscle cramps, or an abnormal heartbeat; or weight loss.

What are some other side effects of entacapone?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

Feeling tired or weak.
Dizziness.
Belly pain.
Constipation.
Upset stomach or throwing up.
Diarrhea.
Dry mouth.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If overdose is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out entacapone?

Store at room temperature.
Store in a dry place. Do not store in a bathroom.
Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

Label

PACKAGE LABEL-PRINCIPAL DISPLAY PANEL – (100 Tablets Bottle)Rising® NDC 16571-689-01

Carbidopa, Levodopa and Entacapone Tablets
Carbidopa, USP     12.5 mg
Levodopa, USP        50 mg
and
Entacapone, USP   200 mg
100 Tablets              Rx Only
Do not combine tablets to achieve a higher strength tablet due to the risk of entacapone overdose.