Carbidopa
Also known as: Methyldopa hydrazine
Carbidopa is inhibitor of L-aromatic amino acid decarboxylase, also called dopa decarboxylase. Chemically Carbidopa is identified as (-)-L-a-hydrazino-3, 4-dihydroxy-a-methylhydrocinnamic acid monohydrate. It has no direct therapeutic effects of its own but rather is used only to protect levodopa and L-5-hydroxytryptophan, both of which are decarboxylated by aromatic amino acid decarboxylase. Carbidopa is used to treat symptoms of parkinson's disease. If patient is switching from plain levodopa to combination of levodopa and it, levodopa must be discontinued for 8 hours before taking this combination drug.
Primary Characteristics
Carbidopa is also known as Methyldopa hydrazine.
It is of Synthetic origin and belongs to Propionic Acid.
It belongs to L-amino acid decarboxylase inhibitor pharmacological group on the basis of mechanism of action and also classified in Antiparkinson Agents pharmacological group.
Molecular Weight: 244.25 · pKa: 2.3, 7.3 · Solubility in Water: slightly soluble · Solubility in Alcohol: almost Insoluble · Non-proprietary name: Carbidopa.
Pharmacokinetics
Absorption: Carbidopa has an oral bioavailability is 64% (±24%).
Distribution: Carbidopa has a plasma protein binding is 36%.
Elimination: plasma half-life is 2-3 hr, renal excretion is 30%.
Advertisement
Indications
Carbidopa is primarily indicated in conditions like Dopa-responsive dystonia, Parkinsonism, Parkinson's disease, Postencephalitic parkinsonism, Symptomatic parkinsonism.
Contraindications
Carbidopa is contraindicated in conditions like Psychosis, Narrow-angle glaucoma.
Dosage
Carbidopa's dosage details are as follows:
| Dose | Single Dose | Frequency | Route | Instructions |
|---|---|---|---|---|
| Adult Dosage | ||||
| 25 mg | 25 mg | Every 8h | PO | Initially with levodopa 100 mg. |
| 87.5 mg | 87.5 mg | Every 24h | PO | Maintenance in div.doses, With levodopa750 2000 mg, |
| Paediatric Dosage (20kg) | ||||
| 0 – 0 | — | — | — | Not Recommended in this Age Group |
| Neonatal Dosage (3kg) | ||||
| 0 – 0 | — | — | — | Not Recommended in this Age Group |
Drug Interactions
Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.
Side Effects
Carbidopa in overdosage may give rise to further complications which include Psychiatric disturbances , Fluctuating disability , Postural hypotension , Dyskinesias .
Carbidopa produces potentially life-threatening effects which include Neuroleptic Malignant Syndrome . Careful monitoring is needed with proper medical management.
Carbidopa is known to cause more or less tolerable side effects which are usually transient. These include GI upset, Nausea, Palpitation, Vomiting .
Warnings / Precautions
Interference in Pathology
Carbidopa may interfere in the diagnosis of Serum tests for bilirubin, catecholamines, creatinine, glucose and uric acid. , Urine Tests for AminoAcids, Creatinine, Creatinine Clearance, estrogens, glucose, homogentisic acid , Urine Tests for Uric Acid, ketones, vinillylmandelic acid, and 5-OHindolacetic acid. .
Available Brands
Storage Conditions
Drug Classification
- 1.9.1 — Drugs used in parkinsonism