Sinemet 25/100/Sinemet 25/250 Drug Interactions

Caution should be exercised when the following drugs are administered concomitantly with Sinemet:
Symptomatic postural hypotension can occur when Sinemet is added to the treatment of patients receiving antihypertensive drugs. Therefore, when therapy with Sinemet is started, dosage adjustment of the antihypertensive drug may be required. (For patients receiving MAOIs, see Contraindications.)
There have been rare reports of adverse reactions, including hypertension and dyskinesia, resulting from the concomitant use of tricyclic antidepressants and Sinemet.
Phenothiazines and butyrophenones 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 Sinemet should be carefully observed for loss of therapeutic response.
Since levodopa competes with certain amino acids, the absorption of levodopa may be impaired in some patients on a high-protein diet. Co-administration with milk will significantly reduce levodopa level.