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January 1975

Diphenylhydantoin: Blocking of Levodopa Effects

Author Affiliations

From the Medical Research Center, Brookhaven National Laboratory, Upton, NY.

Arch Neurol. 1975;32(1):44-46. doi:10.1001/archneur.1975.00490430066011

Diphenylhydantoin (DPH) diminished the therapeutic effects of levodopa both in patients with parkinsonism and in patients with chronic manganese poisoning, as well as the levodopa-dependent dyskinesia for which the former were selected. In patients with Huntington chorea, it enhanced chorea and mental agitation and, thus, failed to conform with the postulated pharmacological reciprocity between Parkinson disease and Huntington chorea. These findings are in agreement with experiments done in animals in which DPH blocked a neuronal response to dopamine.

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