Papaverine Levodopa

Levodopa interacts with many different drugs. When levodopa is used with phenytoin, reserpine, and papaverine, there is a decrease in response to levodopa The risk of a hypertensive crisis increases when levodopa is used with the monoamine oxidase inhibitors (see Chap. 31). Foods high in pyridoxine (vitamin B6) or vitamin B6 preparations reverse the effect of levodopa However, when carbidopa is used with levodopa, pyridoxine has no effect on the action of levodopa hi fact, when levodopa and carbidopa are given together, pyridoxine may be prescribed to decrease the adverse effects associated with levodopa... 

Case reports describe a deterioration in the control of parkinsonism in patients taking levodopa when given papaverine, but a controlled trial failed to confirm this interaction. 

A woman with long-standing parkinsonism, well controlled on levodopa (with the later addition of carbidopa), began to show a steady worsening of her parkinsonism within a week of additionally starting papaverine 100 mg daily for cerebral vascular insufficiency. The deterioration continued until the papaverine was withdrawn. The normal response to levodopa returned within a week. Four other patients had a similar response. Two other similar cases have been described in another report. ... 

A double-blind crossover trial in 9 patients with parkinsonism taking levodopa (range 100 to 750 mg daily) plus a dopa-decarboxylase inhibitor did not find any changes in disease control when they also took papaverine hydrochloride 150 mg daily for 3 weeks. Two patients were also taking bromocriptine 40 mg daily and two trihexyphenidyl 15 mg daily. ... 

Montastruc JL, Rascol O, Belin J, Ane M, Rascol A. Does papaverine interact with levodopa inParkinson sdisease /inwAfe ro/(198 22, 558-9. 

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