Carbidopa and Levodopa (Page 4 of 5)

OVERDOSAGE

Management of acute overdosage with carbidopa and levodopa tablets is the same as management of acute overdosage with levodopa. Pyridoxine is not effective in reversing the actions of carbidopa and levodopa tablets.

General supportive measures should be employed, along with immediate gastric lavage. Intravenous fluids should be administered judiciously and an adequate airway maintained. Electrocardiographic monitoring should be instituted and the patient carefully observed for the development of arrhythmias; if required, appropriate antiarrhythmic therapy should be given. The possibility that the patient may have taken other drugs as well as carbidopa and levodopa tablets should be taken into consideration. To date, no experience has been reported with dialysis; hence, its value in overdosage is not known.
Based on studies in which high doses of levodopa and/or carbidopa were administered, a significant proportion of rats and mice given single oral doses of levodopa of approximately 1,500 mg/kg to 2,000 mg/kg are expected to die. A significant proportion of infant rats of both sexes are expected to die at a dose of 800 mg/kg. A significant proportion of rats are expected to die after treatment with similar doses of carbidopa. The addition of carbidopa in a 1:10 ratio with levodopa increases the dose at which a significant proportion of mice are expected to die to 3,360 mg/kg.

DOSAGE AND ADMINISTRATION

The optimum daily dosage of carbidopa and levodopa tablets must be determined by careful titration in each patient. Carbidopa and levodopa tablets are available in a 1:4 ratio of carbidopa to levodopa (carbidopa and levodopa tablets 25 mg/100 mg) as well as 1:10 ratio (carbidopa and levodopa tablets 25 mg/250 mg and carbidopa and levodopa tablets 10 mg/100 mg). Tablets of the two ratios may be given separately or combined as needed to provide the optimum dosage.

Studies show that peripheral dopa decarboxylase is saturated by carbidopa at approximately 70 mg to 100 mg a day. Patients receiving less than this amount of carbidopa are more likely to experience nausea and vomiting.

Usual Initial Dosage

Dosage is best initiated with one tablet of carbidopa and levodopa tablets 25 mg/100 mg three times a day. This dosage schedule provides 75 mg of carbidopa per day. Dosage may be increased by one tablet every day or every other day, as necessary, until a dosage of eight tablets of carbidopa and levodopa tablets 25 mg/100 mg a day is reached.

If carbidopa and levodopa tablets 10 mg/100 mg are used, dosage may be initiated with one tablet three or four times a day. However, this will not provide an adequate amount of carbidopa for many patients. Dosage may be increased by one tablet every day or every other day until a total of eight tablets (2 tablets q.i.d.) is reached.

How to Transfer Patients from Levodopa

Levodopa must be discontinued at least twelve hours before starting carbidopa and levodopa tablets. A daily dosage of carbidopa and levodopa tablets should be chosen that will provide approximately 25% of the previous levodopa dosage. Patients who are taking less than 1,500 mg of levodopa a day should be started on one tablet of carbidopa and levodopa tablets 25 mg/100 mg three or four times a day. The suggested starting dosage for most patients taking more than 1,500 mg of levodopa is one tablet of carbidopa and levodopa tablets 25 mg/250 mg three or four times a day.

Maintenance

Therapy should be individualized and adjusted according to the desired therapeutic response. At least 70 mg to 100 mg of carbidopa per day should be provided. When a greater proportion of carbidopa is required, one tablet of carbidopa and levodopa tablets 25 mg/100 mg may be substituted for each tablet of carbidopa and levodopa tablets 10 mg/100 mg. When more levodopa is required, carbidopa and levodopa tablets 25 mg/250 mg should be substituted for carbidopa and levodopa tablets 25 mg/100 mg or carbidopa and levodopa tablets 10 mg/100 mg. If necessary, the dosage of carbidopa and levodopa tablets 25 mg/250 mg may be increased by one-half or one tablet every day or every other day to a maximum of eight tablets a day. Experience with total daily dosages of carbidopa greater than 200 mg is limited.

Because both therapeutic and adverse responses occur more rapidly with carbidopa and levodopa tablets than with levodopa alone, patients should be monitored closely during the dose adjustment period. Specifically, involuntary movements will occur more rapidly with carbidopa and levodopa tablets than with levodopa. The occurrence of involuntary movements may require dosage reduction. Blepharospasm may be a useful early sign of excess dosage in some patients.

Addition of Other Antiparkinsonian Medications

Standard drugs for Parkinson’s disease, other than levodopa without a decarboxylase inhibitor, may be used concomitantly while carbidopa and levodopa tablets are being administered, although dosage adjustments may be required.

Interruption of Therapy

Sporadic cases of hyperpyrexia and confusion have been associated with dose reductions and withdrawal of carbidopa and levodopa tablets. Patients should be observed carefully if abrupt reduction or discontinuation of carbidopa and levodopa tablets are required, especially if the patient is receiving neuroleptics. (See WARNINGS.)

If general anesthesia is required, carbidopa and levodopa tablets may be continued as long as the patient is permitted to take fluids and medication by mouth. If therapy is interrupted temporarily, the patient should be observed for symptoms resembling NMS, and the usual daily dosage may be administered as soon as the patient is able to take oral medication.

HOW SUPPLIED

Carbidopa and Levodopa tablets, USP 10 mg/100 mg are light blue, mottled, round, uncoated tablets debossed with ‘SG’ on one side and ‘457′ on the other. They are supplied as follows:

Bottle of 30’s NDC 50228-457-30
Bottle of 100’s NDC 50228-457-01
Bottle of 500’s NDC 50228-457-05
Bottle of 1000’s NDC 50228-457-10

Carbidopa and Levodopa tablets, USP 25 mg/100 mg are light yellow, mottled, round, uncoated tablets debossed with ‘SG’ on one side and ‘458′ on the other. They are supplied as follows:

Bottle of 30’s NDC 50228-458-30
Bottle of 100’s NDC 50228-458-01
Bottle of 500’s NDC 50228-458-05
Bottle of 1000’s NDC 50228-458-10

Carbidopa and Levodopa tablets, USP 25 mg/250 mg are light blue, mottled, round, uncoated tablets debossed with ‘SG’ on one side and ‘459′ on the other. They are supplied as follows:

Bottle of 30’s NDC 50228-459-30
Bottle of 100’s NDC 50228-459-01
Bottle of 500’s NDC 50228-459-05
Bottle of 1000’s NDC 50228-459-10

Storage and Handling

Store at 20° to 25°C (68° to 77°F), excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature]. Store in a tightly closed container, protected from light and moisture.

Dispense in a tightly closed, light-resistant container.


Manufactured by:
ScieGen Pharmaceuticals, Inc.
Hauppauge, NY 11788

Rev. 5/2021

Repackaging Information

Please reference the How Supplied section listed above for a description of individual tablets. This drug product has been received by Aphena Pharma — TN in a manufacturer or distributor packaged configuration and repackaged in full compliance with all applicable cGMP regulations. The package configurations available from Aphena are listed below:

Count25 mg / 100 mg
9071610-647-60
18071610-647-80

Store between 20°-25°C (68°-77°F). See USP Controlled Room Temperature. Dispense in a tight light-resistant container as defined by USP. Keep this and all drugs out of the reach of children.

Repackaged by:
Aphena Pharma Solutions -- TN
Cookeville, TN 38506
20220502JK

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