Carbidopa

-1.9

-1.9

203-208 °C

203 - 205 °C

142.4 Ų [M+H]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]

142.42 Ų [M+H-H2O]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]；143.39 Ų [M+H]+ [CCS Type: TW; Method: calibrated with polyalanine and drug standards]

This chemical does not meet GHS hazard criteria for 2.7% (2 of 75) of reports.

Danger

H315 (82.7%): Causes skin irritation [Warning Skin corrosion/irritation]；H319 (82.7%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]；H335 (82.7%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]；H351 (12%): Suspected of causing cancer [Warning Carcinogenicity]；H360 (12%): May damage fertility or the unborn child [Danger Reproductive toxicity]

P203, P261, P264, P264+P265, P271, P280, P302+P352, P304+P340, P305+P351+P338, P318, P319, P321, P332+P317, P337+P317, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 75 reports by companies from 10 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.；Reported as not meeting GHS hazard criteria per 2 of 75 reports by companies.；There are 9 notifications provided by 73 of 75 reports by companies with hazard statement code(s).；Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

Skin Irrit. 2 (82.7%)；Eye Irrit. 2A (82.7%)；STOT SE 3 (82.7%)

Muta. 2 (100%)

Because of the irreversible binding of AADC, carbidopa can decrease or deplete peripheral levels of serotonin, dopamine, norepinephrine, and epinephrine. Additionally, research has demonstrated that the irreversible binding of PLP causes nutritional deficiencies in vitamins B3 and B6. Specific carbidopa-induced dyskinesias, including “facial twitching and head bobbing,” have also been described.；Recognizing the adverse effects associated with carbidopa/levodopa combinations is also essential. In addition to dyskinetic movements, there are reports of psychiatric problems, autonomic dysfunction, and sensory/pain symptoms with levodopa use. These non-motor symptoms range from euphoric mood, hallucinations, and worsening cognition, to poor thermoregulation, dysphagia, and peripheral neuropathy and can vary depending on the “on/off” fluctuations of levodopa.

There is little data to suggest a possibility for or symptoms of carbidopa toxicity. However, reported data indicate that carbidopa/levodopa intestinal gel infusion can cause significant damage to small nerve fibers leading to pain and sensory discomfort.

Drug Induced Liver Injury Rank (DILIrank 2.0)

Carbidopa

Ambiguous-DILI-concern

3

Warnings & precautions

DOI:10.1016/j.drudis.2016.02.015

When mixed with [levodopa], carbidopa inhibits the peripheral conversion of [levodopa] to dopamine and the decarboxylation of [oxitriptan] to serotonin by aromatic L-amino acid decarboxylase. This results in an increased amount of [levodopa] and [oxitriptan] available for transport to the central nervous system. Carbidopa also inhibits the metabolism of [levodopa] in the GI tract, thus, increasing the bioavailability of [levodopa]. The presence of additional units of circulating [levodopa] can increase the effectiveness of the still functional dopaminergic neurons and it has been shown to alleviate symptoms for a time. The action of carbidopa is very important as [levodopa] is able to cross the blood-brain barrier while dopamine cannot. Hence the administration of carbidopa is essential to prevent the transformation of external [levodopa] to dopamine before reaching the main action site in the brain. The coadministration of carbidopa with [levodopa] has been shown to increase the half-life of [levodopa] more than 1.5 times while increasing the plasma level and decreasing clearance. The combination therapy has also shown an increase of the recovery of [levodopa] in urine instead of dopamine which proves a reduced metabolism. This effect has been highly observed by a significant reduction in [levodopa] requirements and a significant reduction in the presence of side effects such as nausea. It has been observed that the effect of carbidopa is not dose-dependent.

Carbidopa is an inhibitor of the DDC which in order, inhibits the peripheral metabolism of levodopa. DDC is very important in the biosynthesis of L-tryptophan to serotonin and the modification of L-DOPA to dopamine. DDC can be found in the body periphery and in the blood-brain barrier. The action of carbidopa is focused on peripheral DDC as this drug cannot cross the blood-brain barrier. Hence, it will prevent the metabolism of [levodopa] in the periphery but it will not have any activity on the generation of dopamine in the brain.

The loss of the hydrazine functional group (probably as molecular nitrogen) represents the major metabolic pathway for carbidopa. There are several metabolites of carbidopa metabolism including 3-(3,4-dihydroxyphenyl)-2-methylpropionic acid, 3-(4-hydroxy-3-methoxyphenyl)-2-methylpropionic acid, 3-(3-hydroxyphenyl)-2-methylpropionic acid, 3-(4-hydroxy-3-methoxyphenyl)-2-methyllactic acid, 3-(3-hydroxyphenyl)-2-methyllactic acid, and 3,4-dihydroxyphenylacetone (1,2).

MNX7R8C5VO

CARBIDOPA

Established Pharmacologic Class [EPC] - Aromatic Amino Acid Decarboxylation Inhibitor

Mechanisms of Action [MoA] - DOPA Decarboxylase Inhibitors

Carbidopa is an Aromatic Amino Acid Decarboxylation Inhibitor. The mechanism of action of carbidopa is as a DOPA Decarboxylase Inhibitor.

Agents used in the treatment of Parkinson's disease. The most commonly used drugs act on the dopaminergic system in the striatum and basal ganglia or are centrally acting muscarinic antagonists.

Any drugs that are used for their effects on dopamine receptors, on the life cycle of dopamine, or on the survival of dopaminergic neurons.

Compounds and drugs that block or inhibit the enzymatic action of AROMATIC AMINO ACID DECARBOXYLASES. Pharmaceutical agents in this category are used in conjunction with LEVODOPA in order to slow its metabolism.

When [levodopa]/carbidopa is administered orally, 40-70% of the administered dose is absorbed. Once absorbed, carbidopa shows bioavailability of 58%. A maximum concentration of 0.085 mcg/ml was achieved after 143 min with an AUC of 19.28 mcg.min/ml.

In animal studies, 66% of the administered dose of carbidopa was eliminated via the urine while 11% was found in feces. These studies were performed in humans and it was observed a urine excretion covering 50% of the administered dose.

The volume of distribution reported for the combination therapy of carbidopa/[levodopa] is of 3.6 L/kg. However, carbidopa is widely distributed in the tissues, except in the brain. After one hour, carbidopa is found mainly in the kidney, lungs, small intestine and liver.

The reported clearance rate for the combination therapy of [levodopa]/carbidopa is 51.7 L/h.