Vexdopa Drug Interactions

Caution should be exercised when the following drugs are administered concomitantly with Carbidopa-Levodopa. Symptomatic postural hypotension occurred when Carbidopa-Levodopa was added to the treatment of a patient receiving antihypertensive drugs. Therefore, when therapy with Carbidopa-Levodopa is started, dosage adjustment of the anti-hypertensive drug may be required.
For patients receiving MAO inhibitors (Type A or B), see Contraindications. Concomitant therapy with selegiline and Carbidopa-Levodopa may be associated with severe orthostatic hypotension not attributable to Carbidopa-Levodopa alone (see Contraindications).
There have been rare reports of adverse reactions, including hypertension and dyskinesia, resulting from the concomitant use of tricyclic antidepressants and Carbidopa-Levodopa.
Dopamine D2 receptor antagonists (e.g., phenothiazines, butyrophenones, risperidone) and isoniazid may reduce the therapeutic effects of levodopa. In addition, the beneficial effects of levodopa in Parkinson's disease have been reported to be reversed by phenytoin and papaverine. Patients taking these drugs with Carbidopa-Levodopa should be carefully observed for loss of therapeutic response.
Iron salts may reduce the bioavailability of levodopa and carbidopa. The clinical relevance is unclear.
Although metoclopramide may increase the bioavailability of levodopa by increasing gastric emptying, metoclopramide may also adversely affect disease control by its dopamine receptor antagonistic properties.
Carcinogenesis, Mutagenesis, Impairment of Fertility: In a two-year bioassay of Carbidopa-Levodopa, no evidence of carcinogenicity was found in rats receiving doses of approximately two times the maximum daily human dose of carbidopa and four times the maximum daily human dose of levodopa. In reproduction studies with Carbidopa-Levodopa, no effects on fertility were found in rats receiving doses of approximately two times the maximum daily human dose of carbidopa and four times the maximum daily human dose of levodopa.