CARBIDOPA tablet

Country: United States

Language: English

Source: NLM (National Library of Medicine)

Active ingredient:

CARBIDOPA (UNII: MNX7R8C5VO) (CARBIDOPA ANHYDROUS - UNII:KR87B45RGH)

Available from:

Lupin Pharmaceuticals,Inc.

INN (International Name):

CARBIDOPA

Composition:

CARBIDOPA ANHYDROUS 25 mg

Administration route:

ORAL

Prescription type:

PRESCRIPTION DRUG

Therapeutic indications:

Carbidopa tablets are indicated for use with carbidopa-levodopa or with levodopa in the treatment of the symptoms of idiopathic Parkinson's disease (paralysis agitans), postencephalitic parkinsonism, and symptomatic parkinsonism which may follow injury to the nervous system by carbon monoxide intoxication and/or manganese intoxication. Carbidopa is for use with carbidopa-levodopa in patients for whom the dosage of carbidopa-levodopa provides less than adequate daily dosage (usually 70 mg daily) of carbidopa. Carbidopa is for use with levodopa in the occasional patient whose dosage requirement of carbidopa and levodopa necessitates separate titration of each medication. Carbidopa is used with carbidopa-levodopa or with levodopa to permit the administration of lower doses of levodopa with reduced nausea and vomiting, more rapid dosage titration, and with a somewhat smoother response. However, patients with markedly irregular ("on-off") responses to levodopa have not been shown to benefit from the addition of carbidopa. Since carbidopa prevents the reversal of levodopa effects caused by pyridoxine, supplemental pyridoxine (vitamin B6), can be given to patients when they are receiving carbidopa and levodopa concomitantly or as carbidopa-levodopa. Although the administration of carbidopa permits control of parkinsonism and Parkinson's disease with much lower doses of levodopa, there is no conclusive evidence at present that this is beneficial other than in reducing nausea and vomiting, permitting more rapid titration, and providing a somewhat smoother response to levodopa. Certain patients who responded poorly to levodopa alone have improved when carbidopa and levodopa were given concurrently. This was most likely due to decreased peripheral decarboxylation of levodopa rather than to a primary effect of carbidopa on the peripheral nervous system. Carbidopa has not been shown to enhance the intrinsic efficacy of levodopa. In deciding whether to give carbidopa with carbidopa-levodopa or with levodopa to patients who have nausea and/or vomiting, the physician should be aware that, while many patients may be expected to improve, some may not. Since one cannot predict which patients are likely to improve, this can only be determined by a trial of therapy. It should be further noted that in controlled trials comparing carbidopa and levodopa with levodopa alone, about half the patients with nausea and/or vomiting on levodopa alone improved spontaneously despite being retained on the same dose of levodopa during the controlled portion of the trial. Carbidopa is contraindicated in patients with known hypersensitivity to any component of this drug. Nonselective monoamine oxidase (MAO) inhibitors are contraindicated for use with levodopa or carbidopa-levodopa combination products with or without carbidopa. These inhibitors must be discontinued at least two weeks prior to initiating therapy with levodopa. Carbidopa-levodopa, or levodopa may be administered concomitantly with the manufacturer's recommended dose of an MAO inhibitor with selectivity for MAO type B (e.g., selegiline HCl) (see PRECAUTIONS, Drug Interactions ). Levodopa or carbidopa-levodopa products, with or without carbidopa, are contraindicated in patients with narrow-angle glaucoma.

Product summary:

Carbidopa tablets, 25 mg, are light orange to orange colored, round, flat beveled edge debossed with "nl c"on one side and scored on the other side. They are supplied as follows: NDC 43386-980-03 bottles of 30. NDC 43386-980-01 bottles of 100. NDC 43386-980-10 bottles of 1000.

Authorization status:

Abbreviated New Drug Application

Summary of Product characteristics

CARBIDOPA - CARBIDOPA TABLET
LUPIN PHARMACEUTICALS,INC.
----------
CARBIDOPA TABLETS
WHEN CARBIDOPA TABLET IS TO BE GIVEN TO CARBIDOPA-NAIVE PATIENTS WHO
ARE
BEING TREATED WITH LEVODOPA, THE TWO DRUGS SHOULD BE GIVEN AT THE SAME
TIME, STARTING WITH NO MORE THAN 20 TO 25% OF THE PREVIOUS DAILY
DOSAGE OF
LEVODOPA WHEN GIVEN WITHOUT CARBIDOPA TABLETS. AT LEAST TWELVE HOURS
SHOULD
ELAPSE BETWEEN THE LAST DOSE OF LEVODOPA AND INITIATION OF THERAPY
WITH
CARBIDOPA AND LEVODOPA. SEE THE WARNINGS AND DOSAGE AND
ADMINISTRATION SECTIONS BEFORE INITIATING THERAPY.
DESCRIPTION
Carbidopa, an inhibitor of aromatic amino acid decarboxylation, is a
white to creamy
white powder, 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 C
H
N O •H O, and its structural formula is:
Carbidopa tablets contain 25 mg of carbidopa. Inactive ingredients are
microcrystalline
cellulose, FD&C Yellow 6, magnesium stearate and pregelatinized
starch.
Tablet content is expressed in terms of anhydrous carbidopa which has
a molecular
weight of 226.3.
CLINICAL PHARMACOLOGY
Parkinson's disease is a progressive, neurodegenerative disorder of
the extrapyramidal
nervous system affecting the mobility and control of the skeletal
muscular system. Its
characteristic features include resting tremor, rigidity, and
bradykinetic movements.
Symptomatic treatments, such as levodopa therapies, may permit the
patient better
mobility.
MECHANISM OF ACTION
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 apparently because it does not
cross the blood-
brain barrier. However, levodopa, the metabolic precursor of dopamine,
does cross the
10
14
2
4
2
blood-brain barrier, and presumably is converted to dopamine in the
brain. This is
thought to be the mechanism whereby levo