Twindopa Drug Interactions

Caution should be exercised when the following drugs are administered concomitantly with Levodopa + Carbidopa (Twindopa).
Antihypertensive agents: Postural hypotension can occur when Levodopa + Carbidopa (Twindopa) is added to the treatment of patients already receiving antihypertensive drugs. Dosage adjustment of the antihypertensive agent may be required.
Antidepressants: Rarely, reactions including hypertension and dyskinesia have been reported with the concomitant use of tricyclic antidepressants. (See first paragraph of Contraindications for patients receiving MAOIs.)
Anticholinergics: Anticholinergics may affect the absorption and thus the patient's response.
Iron: Studies demonstrate a decrease in the bioavailability of carbidopa and/or levodopa when it is ingested with ferrous sulphate or ferrous gluconate.
Other drugs: To date there has been no indication of interactions that would preclude concurrent use of standard antiparkinsonian drugs.
Dopamine D2 receptor antagonists (e.g. phenothiazines, butyrophenones, and risperidone) and isoniazid, may reduce the therapeutic effects of levodopa. The beneficial effects of levodopa in Parkinson's disease have been reported to be reversed by phenytoin and papaverine. Patients taking these drugs with Levodopa + Carbidopa (Twindopa) should be carefully observed for loss of therapeutic response.
Use of Levodopa + Carbidopa (Twindopa) with dopamine-depleting agents (e.g., tetrabenazine) or other drugs known to deplete monoamine stores is not recommended.
Concomitant therapy with selegiline and carbidopa-levodopa may be associated with severe orthostatic hypotension not attributable to carbidopa-levodopa alone (see Contraindications).
Since levodopa competes with certain amino acids, the absorption of Levodopa + Carbidopa (Twindopa) may be impaired in some patients on a high protein diet.
The effect of simultaneous administration of antacids with Levodopa + Carbidopa (Twindopa) on the bioavailability of levodopa has not been studied.
Levodopa + Carbidopa (Twindopa) may be given to patients with Parkinson's disease and syndrome who are taking vitamin preparations that contain pyridoxine hydrochloride (Vitamin B6).