(S)-carbidopa
(S)-carbidopa Uses, Dosage, Side Effects, Food Interaction and all others data.
(S)-carbidopa presents a chemical denomination of N-amino-alpha-methyl-3-hydroxy-L-tyrosine monohydrate. It potently inhibits aromatic amino acid decarboxylase (DDC) and due to its chemical properties, it does not cross the blood-brain barrier. Due to its activity, carbidopa is always administered concomitantly with levodopa. An individual formulation containing solely carbidopa was generated to treat nausea in patients where the combination therapy levodopa/carbidopa is not efficient reducing nausea.
The first approved product by the FDA containing only carbidopa was developed by Amerigens Pharmaceuticals Ltd and approved on 2014. On the other hand, the combination treatment of carbidopa/levodopa was originally developed by Watson Labs but the historical information by the FDA brings back to the approval of this combination therapy developed by Mayne Pharma in 1992.
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. (S)-carbidopa also inhibits the metabolism of levodopa in the GI tract, thus, increasing the bioavailability of levodopa.
| Trade Name | (S)-carbidopa |
| Availability | Prescription only |
| Generic | Carbidopa |
| Carbidopa Other Names | (S)-carbidopa, Carbidopa, Carbidopum |
| Related Drugs | scopolamine, Sinemet, nadolol, Corgard, Transderm-Scop, belladonna, Sinemet CR, Parcopa, Lodosyn |
| Type | |
| Formula | C10H14N2O4 |
| Weight | Average: 226.2292 Monoisotopic: 226.095356946 |
| Protein binding | It is widely accepted that the protein binding of carbidopa is 76%. However, more studies are required or the presentation of the source of this information. |
| Groups | Approved |
| Therapeutic Class | |
| Manufacturer | |
| Available Country | |
| Last Updated: | September 19, 2023 at 7:00 am |
Uses
(S)-carbidopa is a dopa decarboxylase inhibitor used in combination with levodopa for the symptomatic treatment of idiopathic Parkinson disease and other conditions associated with parkinsonian symptoms.
(S)-carbidopa is indicated with levodopa for the treatment of symptoms of idiopathic Parkinson disease, postencephalitic parkinsonism and symptomatic parkinsonism followed by carbon monoxide or manganese intoxication.
The combination therapy is administered for the reduction of levodopa-driven nausea and vomiting.
The product of carbidopa should be used in patients where the combination therapy of carbidopa/levodopa provide less than the adequate daily dosage.
As well carbidopa can be used in patients where the dosages of carbidopa and levodopa require individual titration.
(S)-carbidopa is also used to associated treatment for these conditions: Parkinson's Disease (PD), Postencephalitic parkinsonism, Symptomatic Parkinson Disease, Levodopa-driven nausea and vomiting
How (S)-carbidopa works
(S)-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.
Toxicity
The LD50 of carbidopa is reported to be in the rat of 4810 mg/kg. In animal studies, carbidopa showed no incidences on neoplasia and showed no effect on the fertility status and development.
No reports of overdosage have been registered with the carbidopa-only product. In the event of overdosage, immediate gastric lavage is recommended as well as intravenous fluid administration. Continuous electrocardiographic monitoring is required.
Food Interaction
No interactions found.(S)-carbidopa Disease Interaction
Volume of Distribution
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.
Elimination Route
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.
Half Life
The reported half-life of carbidopa is of approximately 107 minutes.
Clearance
The reported clearance rate for the combination therapy of levodopa/carbidopa is 51.7 L/h.
Elimination Route
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.
Innovators Monograph
You find simplified version here (S)-carbidopa
