Levodopa / Carbidopa

What it is and how it works

Mechanism of Action 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. 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.

Mechanism class: DOPA Decarboxylase Inhibitors

Indications

INDICATIONS AND USAGE Carbidopa and levodopa orally disintegrating tablets are indicated in the treatment of Parkinson’s disease, post-encephalitic parkinsonism, and symptomatic parkinsonism that may follow carbon monoxide intoxication or manganese intoxication. Carbidopa allows patients treated for Parkinson’s disease to use much lower doses of levodopa. Some patients who responded poorly to levodopa have improved on carbidopa and levodopa orally disintegrating tablets. This is most likely due to decreased peripheral decarboxylation of levodopa caused by administration of carbidopa rather than by a primary effect of carbidopa on the nervous system. Carbidopa has not been shown to enhance the intrinsic efficacy of levodopa. Carbidopa may also reduce nausea and vomiting and permit more rapid titration of levodopa.

Dosage and administration (summary)

DOSAGE AND ADMINISTRATION Instructions for Use/Handling Carbidopa and Levodopa Orally Disintegrating Tablets: Just prior to administration, GENTLY remove the tablet from the bottle with dry hands. IMMEDIATELY place the carbidopa and levodopa orally disintegrating tablet on top of the tongue where it will dissolve in seconds, then swallow with saliva. Administration with liquid is not necessary. The optimum daily dosage of carbidopa and levodopa orally disintegrating tablets must be determined by careful titration in each patient.

Contraindications

CONTRAINDICATIONS Nonselective monoamine oxidase (MAO) inhibitors are contraindicated for use with carbidopa and levodopa orally disintegrating tablets. These inhibitors must be discontinued at least two weeks prior to initiating therapy with carbidopa and levodopa orally disintegrating tablets.

Warnings and precautions

WARNINGS When carbidopa and levodopa orally disintegrating tablets are to be given to patients who are being treated with levodopa, levodopa must be discontinued at least twelve hours before therapy with carbidopa and levodopa orally disintegrating tablets are started. In order to reduce adverse reactions, it is necessary to individualize therapy. See DOSAGE AND ADMINISTRATION section before initiating therapy.

Pregnancy

Pregnancy No teratogenic effects were observed in a study in mice receiving up to 20 times the maximum recommended human dose of carbidopa and levodopa. There was a decrease in the number of live pups delivered by rats receiving approximately two times the maximum recommended human dose of carbidopa and approximately five times the maximum recommen…

Storage and supply

HOW SUPPLIED Carbidopa and Levodopa Orally Disintegrating Tablets, USP are available containing 10 mg or 25 mg of carbidopa, USP, with 100 mg or 250 mg of levodopa, USP providing the following available combinations: 10 mg/100 mg, 25 mg/100 mg or 25 mg/250 mg.

Source: Carbidopa And Levodopa (Carbidopa And Levodopa) — US FDA prescribing information, 2026-01-27, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.