Interactions : אינטראקציות

4.5   Interaction with other medicinal products and other forms of interaction
No interaction studies have been performed with Duodopa. The following interactions are known from the generic combination of levodopa/carbidopa.

Caution is needed in concomitant administration of Duodopa with the following medicinal products:

Antihypertensives
Symptomatic postural hypotension has occurred when combinations of levodopa and a decarboxylase inhibitor are added to the treatment of patients already receiving anti- hypertensives. Dosage adjustment of the antihypertensive agent may be required.

Antidepressants
There have been rare reports of adverse reactions, including hypertension and dyskinesia, resulting from the concomitant administration of tricyclic antidepressants and carbidopa/levodopa preparations.

Anticholinergics
Anticholinergics may act synergistically with levodopa to decrease tremor. However, combined use may exacerbate abnormal involuntary movements. Anticholinergics may decrease the effects of levodopa by delaying its absorption. An adjustment of the dose of Duodopa may be needed.

COMT inhibitors (tolcapone, entacapone)
Concomitant use of COMT (Catechol-O-Methyl Transferase) inhibitors and Duodopa can increase the bioavailability of levodopa. The dose of Duodopa may need adjustment.

Other medicinal products
Dopamine receptor antagonists (some antipsychotics, e.g. phenothiazines, butyrophenons and risperidone and antiemetics, e.g. metoclopramide), benzodiazepines, isoniazide, phenytoin and papaverine can reduce the therapeutic effect of levodopa. Patients taking these medicinal products together with Duodopa should be observed carefully for loss of therapeutic response.

Duodopa can be taken concomitantly with the recommended dose of an MAO inhibitor, which is selective for MAO type B (for instance selegiline-HCl). The dose of levodopa may need to be reduced when an MAO inhibitor selective for type B is added.

Concomitant use of selegiline and levodopa-carbidopa has been associated with serious orthostatic hypotension.

Amantadine has synergic effect with levodopa and may increase levodopa related adverse events. An adjustment of the dose of Duodopa may be needed.

Sympathicomimetics may increase cardiovascular adverse events related to levodopa.

Levodopa forms a chelate with iron in the gastrointestinal tract leading to reduced absorption of levodopa.

As levodopa is competitive with certain amino acids, the absorption of levodopa can be disturbed in patients who are on a protein rich diet.

The effect of administration of antacids and Duodopa on the bioavailability of levodopa has not been studied.