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Carbidopa | Enzyme inhibitor |
Levodopa | Agonist |
Clinical data | |
Trade names | Atamet, Carbilev, Sinemet, others |
AHFS/Drugs.com | Monograph |
MedlinePlus | a601068 |
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Routes of administration | By mouth |
ATC code | |
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CompTox Dashboard (EPA) | |
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Carbidopa/levodopa, also known as levocarb and co-careldopa, is the combination of the two medications carbidopa and levodopa. [6] It is primarily used to manage the symptoms of Parkinson's disease, but it does not slow down the disease or stop it from getting worse. [6] It is taken by mouth. [6] It can take two to three weeks of treatment before benefits are seen. [7] Each dose then begins working in about ten minutes to two hours with a duration of effect of about five hours. [7] [8] [9]
Common side effects include movement problems and nausea. [6] More serious side effects include depression, low blood pressure with standing, sudden onset of sleepiness, psychosis, and increased risk-taking behavior. [6] [10] Carbidopa prevents the breakdown of levodopa outside the brain. [10] In the brain, levodopa is broken down into dopamine, its active form. [10] Carbidopa also helps prevent some of the nausea which levodopa causes. [11]
It is on the World Health Organization's List of Essential Medicines. [12] It is available as a generic medication. [10] In 2022, it was the 278th most commonly prescribed medication in the United States, with more than 700,000 prescriptions. [13] [14]
It is primarily used to improve the symptoms of Parkinson's disease but does not change the course of the disease. [6] It can take two to three weeks of treatment before benefits are seen. [7] Each dose then begins working in about ten minutes to two hours depending on the formulation, with a duration of effect of about five hours. [7] [8] [9]
A formulation that can be given in an intra-intestinal pump, known as Duodopa, is being developed. [15] [16]
Other uses include for dopamine-responsive dystonia (DRD) and restless legs syndrome. [10] [17] [18] Using carbidopa/levodopa may lead to augmentation syndrome, with increasing persistence of restless legs syndrome, and increasing severity. [18]
There is tentative evidence that it is useful in amblyopia when used with other treatments. [19]
Common side effects include dizziness, drowsiness, blurred vision, vomiting, nausea, dry mouth, low appetite, heartburn, diarrhea, constipation, frequent sneezing, stuffiness of the nose, any of the symptoms of ordinary common cold, cough, muscle pain, hallucinations, numbness or a tingling sensation, disturbances of sleep, skin rash, itching, and/or headache. [20]
Less common, but more serious, side effects can include very frequent blinking or twitching of the eyes, fainting, mood changes such as confusion, depression, hallucinations, thoughts of suicide, or unusual strong urges (such as increased gambling), increases in the sex-drive, delusions (strongly-felt belief in something which is obviously not true), worsening of involuntary movements or spasms, and/or other movement problems.
Levodopa is converted to dopamine via the action of a naturally occurring enzyme called DOPA decarboxylase. [21] This occurs both in the peripheral circulation and in the central nervous system after levodopa has crossed the blood brain barrier. Activation of central dopamine receptors improves the symptoms of Parkinson's disease; however, activation of peripheral dopamine receptors causes nausea and vomiting. For this reason levodopa is usually administered in combination with a DOPA decarboxylase inhibitor (DDCI), in this case carbidopa, which is very polar (and charged at physiologic pH) and cannot cross the blood brain barrier, however prevents peripheral conversion of levodopa to dopamine and thereby reduces the unwanted peripheral side effects of levodopa. Use of carbidopa also increases the quantity of levodopa in the bloodstream that is available to enter the brain.
In 1960, the Austrian biochemist Oleh Hornykiewicz, while at the University of Vienna, examined results of autopsies of patients who had died with Parkinson's disease. He suggested that the disease was associated with, or caused by, a reduction in the levels of dopamine in the basal ganglia of the brain. Since dopamine itself did not enter the brain, he tried treating twenty patients with a racemic mixture of dihydroxyphenylalanine (DOPA), which could enter the brain and be converted there to dopamine by the action of DOPA decarboxylase. His results were positive, as were those of another trial in Montreal run by André Barbeau. Unfortunately, other investigators were unable to replicate these early results, and the use of DOPA remained in question until 1967, when George Cotzias at the Brookhaven National Laboratories in Upton, New York, used megadoses of DOPA, up to 16 grams per day. Not long after these results became known, Curt Porter at Merck showed that L-DOPA was the active stereoisomer, thus reducing the effective dose to half. [22]
With L-DOPA identified as the active form, Alfred Pletscher and his colleagues at Hoffman-LaRoche synthesized benserazide, an inhibitor of DOPA decarboxylase, which further reduced the required dose. A drug combining L-DOPA with benserazide was marketed under the brand name of Madopar. Independent work was carried out by Victor Lotti at Merck in West Point, Pennsylvania. Merck had already synthesized and patented carbidopa, another dopa decarboxylase inhibitor in 1962, and in 1971 Lotti showed that the use of the L-form of carbidopa, further reduced the therapeutic dose of L-DOPA. The combination of L-carbidopa and L-DOPA was marketed under the brand name of Sinemet. [22]
It is available as a generic medication. [10]
The generic name under the BAN system is Co-careldopa.
It is sold under several brand names, including Sinemet (Merck Sharp & Dohme Limited), Pharmacopa, Atamet, Apo-Levocarb, Duodopa, Kinson, and Pharmacopa, among others.
Extended-release formulations are sold as Rytary and Sinemet-CR. An extended-release enteral solution is sold as Duopa.
In 1991, Merck licensed the rights to the manufacture and sale of Sinemet to a newly created joint venture, DuPont Merck Pharmaceutical Company. That same year, approvals for a sustained release formulation (Sinemet CR) which could be taken less frequently were also obtained. [23] DuPont purchased Merck's share in the joint venture in 1998 and began operating the company as DuPont Pharmaceuticals (DuPont Pharma), but Merck continued to manufacture the drug for DuPont. [24] Starting in late 2009 and continuing into 2011 Merck stopped manufacturing the drug while awaiting regulatory approvals due to a change in the supplier of the active ingredient. This resulted in shortages of the brand name products Sinemet and Sinemet CR, although alternative generic versions were still available. [25]
l-DOPA, also known as l-3,4-dihydroxyphenylalanine and used medically as levodopa, is made and used as part of the normal biology of some plants and animals, including humans. Humans, as well as a portion of the other animals that utilize l-DOPA, make it via biosynthesis from the amino acid l-tyrosine.
Carbidopa (Lodosyn) is a drug given to people with Parkinson's disease in order to inhibit peripheral metabolism of levodopa. This property is significant in that it allows a greater proportion of administered levodopa to cross the blood–brain barrier for central nervous system effect, instead of being peripherally metabolised into substances unable to cross said barrier.
Dyskinesia refers to a category of movement disorders that are characterized by involuntary muscle movements, including movements similar to tics or chorea and diminished voluntary movements. Dyskinesia can be anything from a slight tremor of the hands to an uncontrollable movement of the upper body or lower extremities. Discoordination can also occur internally especially with the respiratory muscles and it often goes unrecognized. Dyskinesia is a symptom of several medical disorders that are distinguished by their underlying causes.
Benserazide is a peripherally acting aromatic L-amino acid decarboxylase or DOPA decarboxylase inhibitor, which is unable to cross the blood–brain barrier.
Dopaminergic means "related to dopamine", a common neurotransmitter. Dopaminergic substances or actions increase dopamine-related activity in the brain.
Entacapone, sold under the brand name Comtan among others, is a medication commonly used in combination with other medications for the treatment of Parkinson's disease. Entacapone together with levodopa and carbidopa allows levodopa to have a longer effect in the brain and reduces Parkinson's disease signs and symptoms for a greater length of time than levodopa and carbidopa therapy alone.
Tolcapone, sold under the brand name Tasmar, is a medication used to treat Parkinson's disease (PD). It is a selective, potent and reversible nitrocatechol-type inhibitor of the enzyme catechol-O-methyltransferase (COMT). It has demonstrated significant liver toxicity, which has led to suspension of marketing authorisations in a number of countries.
In the management of Parkinson's disease, due to the chronic nature of Parkinson's disease (PD), a broad-based program is needed that includes patient and family education, support-group services, general wellness maintenance, exercise, and nutrition. At present, no cure for the disease is known, but medications or surgery can provide relief from the symptoms.
A catechol-O-methyltransferase inhibitor is a drug that inhibits the enzyme catechol-O-methyltransferase. This enzyme methylates catecholamines such as dopamine, norepinephrine and epinephrine. It also methylates levodopa. COMT inhibitors are indicated for the treatment of Parkinson's disease in combination with levodopa and an aromatic L-amino acid decarboxylase inhibitor. The therapeutic benefit of using a COMT inhibitor is based on its ability to prevent the methylation of levodopa to 3-O-methyldopa, thus increasing the bioavailability of levodopa. COMT inhibitors significantly decrease off time in people with Parkinson's disease also taking carbidopa/levodopa.
Droxidopa, also known as L-threo-dihydroxyphenylserine (L-DOPS) and sold under the brand names Northera and Dops among others, is sympathomimetic medication which is used in the treatment of hypotension and for other indications. It is taken by mouth.
Levodopa, also known as L-DOPA and sold under many brand names, is a dopaminergic medication which is used in the treatment of Parkinson's disease and certain other conditions like dopamine-responsive dystonia and restless legs syndrome. The drug is usually used and formulated in combination with a peripherally selective aromatic L-amino acid decarboxylase (AAAD) inhibitor like carbidopa or benserazide. Levodopa is taken by mouth, by inhalation, through an intestinal tube, or by administration into fat.
Carbidopa/levodopa/entacapone, sold under the brand name Stalevo among others, is a dopaminergic fixed-dose combination medication that contains carbidopa, levodopa, and entacapone for the treatment of Parkinson's disease.
An aromatic L-amino acid decarboxylase inhibitor (synonyms: DOPA decarboxylase inhibitor, extracerebral decarboxylase inhibitor, DDCI and AAADI) is a medication of type enzyme inhibitor which inhibits the synthesis of dopamine by the enzyme aromatic L-amino acid decarboxylase (AADC, AAAD, or DOPA decarboxylase). It is used to inhibit the decarboxylation of L-DOPA to dopamine outside the brain, i.e. in the blood. This is primarily co-administered with L-DOPA to combat Parkinson's disease. Administration can prevent common side-effects, such as nausea and vomiting, as a result of interaction with D2 receptors in the vomiting center (or cheomoreceptor trigger zone) located outside the blood–brain barrier.
Safinamide, sold under the brand name Xadago, is a medication used as treatment for Parkinson's disease with "off" episodes; it has multiple modes of action, including the inhibition of monoamine oxidase B.
Dopamine dysregulation syndrome (DDS) is a dysfunction of the reward system observed in some individuals taking dopaminergic medications for an extended length of time. It is characterized by severely disinhibited patterns of behavior, leading to problems such as addiction to the offending medication, gambling addiction, or compulsive sexual behavior, along with a general orientation towards immediate gratification. It typically occurs in people with Parkinson's disease (PD) or restless legs syndrome (RLS) who have taken dopamine agonist medications for an extended period of time.
Levodopa-induced dyskinesia (LID) is a form of dyskinesia associated with levodopa (l-DOPA), used to treat Parkinson's disease. It often involves hyperkinetic movements, including chorea, dystonia, and athetosis.
Parkinson's disease is the 2nd most prevalent neurological disorder within the United States and Europe, affecting around 1% of the population over the age of 60. While the link connecting the onset of Parkinson's disease to environmental factors is known, the link between dietary patterns and the disease is just beginning to be researched more fully. Additionally, other research has sought to examine the symptoms of the disease and propose methods on how to alleviate these symptoms through changes in diet. Current medications that work to alleviate the symptoms of Parkinson's disease can also be made more effective through changes in diet.
Opicapone, sold under the brand name Ongentys, is a medication which is administered together with levodopa in people with Parkinson's disease. Opicapone is a catechol-O-methyltransferase (COMT) inhibitor.
Monoamine precursors are precursors of monoamines and monoamine neurotransmitters in the body. The amino acids L-tryptophan and L-5-hydroxytryptophan are precursors of serotonin and melatonin, while the amino acids L-phenylalanine, L-tyrosine, and L-DOPA (levodopa) are precursors of dopamine, epinephrine (adrenaline), and norepinephrine (noradrenaline).
Melevodopa/carbidopa, sold under the brand name Sirio, is a combination of melevodopa, a prodrug of the dopamine precursor and hence non-selective dopamine receptor agonist levodopa (L-DOPA), and carbidopa, a peripherally selective aromatic L-amino acid decarboxylase (AAAD) inhibitor, which is used in the treatment of Parkinson's disease in Italy. It is taken orally in the form of tablets.