SINADOPA

What it is

SINADOPA is a combination of levodopa, the metabolic precursor of dopamine, and carbidopa, an aromatic amino acid decarboxylase inhibitor, for the treatment of Parkinson's disease and syndrome. SINADOPA is available in two strengths: 100 mg levodopa with 25 mg carbidopa (as monohydrate), and 250 mg levodopa with 25 mg carbidopa (as monohydrate).

Approved indications

— Treatment of Parkinson's disease and syndrome.

Dosing overview

The optimum daily dosage of SINADOPA must be determined by careful titration in each patient, and dosage should be titrated to individual patient needs. Dosage is best initiated with one tablet three times a day (providing 75 mg of carbidopa per day), with increases by one tablet every day or every other day, as necessary, until a dosage equivalent of eight tablets a day is reached. At least 70 to 100 mg of carbidopa per day should be provided for optimal inhibition of extracerebral decarboxylation of levodopa, with usual dose being 3 tablets daily and maximum 8 tablets daily.

Key safety warnings

Dyskinesia may occur in patients previously treated with levodopa alone because carbidopa permits more levodopa to reach the brain and thus more dopamine to be formed; the occurrence of dyskinesia may require dosage reduction. Levodopa has been associated with somnolence and episodes of sudden sleep onset, including sudden onset of sleep during daily activities in some cases without awareness or warning signs reported very rarely; patients must be informed of this and advised to exercise caution while driving or operating machines during treatment. All patients should be monitored carefully for the development of mental changes, depression with suicidal tendencies, or other serious antisocial behaviour. Patients should be regularly monitored for the development of impulse control disorders, including pathological gambling, hypersexuality, increased libido, compulsive spending/buying, and binge eating, which have been reported in patients taking dopamine agonists for the treatment of Parkinson's disease, especially at high doses. Epidemiological studies have shown that patients with Parkinson's disease have a higher risk (2- to approximately 6-fold higher) of developing melanoma than the general population; whether the increased risk was due to Parkinson's disease or other factors such as drugs used to treat Parkinson's disease is unclear, and patients and providers are advised to monitor for melanomas frequently and on a regular basis when using SINADOPA.

Contraindications

Monoamine oxidase inhibitors (MAOIs) should not be given concomitantly with SINADOPA, and MAOIs must be discontinued at least 2 weeks prior to initiating therapy. SINADOPA is contraindicated in patients with known hypersensitivity to this drug or any component of this medication, and in patients with narrow-angle glaucoma. Because levodopa may activate a malignant melanoma, it should not be used in patients with suspicious undiagnosed skin lesions or history of melanoma.

PBS listing

No information regarding PBS listing for SINADOPA is available in the provided documents.

Regulatory history

SINADOPA was first listed on the Australian Register of Therapeutic Goods on 11 January 2018, with four registered variants including 100 mg and 250 mg levodopa formulations in both bottle and blister pack presentations.