Carbidopa - Warnings and Precautions

WARNINGS When patients are receiving levodopa without a decarboxylase inhibitor, levodopa must be discontinued at least twelve hours before carbidopa and levodopa extended-release tablets are started.

In order to reduce adverse reactions, it is necessary to individualize therapy.

See DOSAGE AND ADMINISTRATION section before initiating therapy.

Carbidopa and levodopa extended-release tablets should be substituted at a dosage that will provide approximately 25% of the previous levodopa dosage (see DOSAGE AND ADMINISTRATION ).

Carbidopa does not decrease adverse reactions due to central effects of levodopa.

By permitting more levodopa to reach the brain, particularly when nausea and vomiting is not a dose-limiting factor, certain adverse central nervous system (CNS) effects, e.g., dyskinesias, will occur at lower dosages and sooner during therapy with carbidopa and levodopa extended-release than with levodopa alone.

Patients receiving carbidopa and levodopa extended-release tablets may develop increased dyskinesias compared to carbidopa and levodopa tablets.

Dyskinesias are a common side effect of carbidopa and levodopa treatment.

The occurrence of dyskinesias may require dosage reduction.

All patients should be observed carefully for the development of depression with concomitant suicidal tendencies.

Carbidopa and levodopa extended-release tablets should be administered cautiously to patients with severe cardiovascular or pulmonary disease, bronchial asthma, renal, hepatic or endocrine disease.

As with levodopa, care should be exercised in administering carbidopa and levodopa extended-release tablets to patients with a history of myocardial infarction who have residual atrial, nodal, or ventricular arrhythmias.

In such patients, cardiac function should be monitored with particular care during the period of initial dosage adjustment, in a facility with provisions for intensive cardiac care.

As with levodopa, treatment with carbidopa and levodopa extended-release tablets may increase the possibility of upper gastrointestinal hemorrhage in patients with a history of peptic ulcer.

Falling Asleep During Activities of Daily Living and Somnolence Patients taking carbidopa and levodopa extended-release tablets alone or with other dopaminergic drugs have reported suddenly falling asleep without prior warning of sleepiness while engaged in activities of daily living (includes operation of motor vehicles).

Road traffic accidents attributed to sudden sleep onset have been reported.

Although many patients reported somnolence while on dopaminergic medications, there have been reports of road traffic accidents attributed to sudden onset of sleep in which the patient did not perceive any warning signs, such as excessive drowsiness, and believed that they were alert immediately prior to the event.

Sudden onset of sleep has been reported to occur as long as one year after the initiation of treatment.

Falling asleep while engaged in activities of daily living usually occurs in patients experiencing pre-existing somnolence, although some patients may not give such a history.

For this reason, prescribers should reassess patients for drowsiness or sleepiness especially since some of the events occur well after the start of treatment.

Prescribers should be aware that patients may not acknowledge drowsiness or sleepiness until directly questioned about drowsiness or sleepiness during specific activities.

Patients should be advised to exercise caution while driving or operating machines during treatment with carbidopa and levodopa extended-release tablets.

Patients who have already experienced somnolence or an episode of sudden sleep onset should not participate in these activities during treatment with carbidopa and levodopa extended-release tablets.

Before initiating treatment with carbidopa and levodopa extended-release tablets, advise patients about the potential to develop drowsiness and ask specifically about factors that may increase the risk for somnolence with carbidopa and levodopa extended-release tablets such as the use of concomitant sedating medications and the presence of sleep disorders.

Consider discontinuing carbidopa and levodopa extended-release tablets in patients who report significant daytime sleepiness or episodes of falling asleep during activities that require active participation (e.g., conversations, eating, etc.).