Abstract: An antiparkinsonian agent comprising DL- or L-threo-3,4-dihydroxyphenylserine and a decarboxylase inhibitor (e.g. carbidopa and benserazide), which is useful for the treatment of parkinson's disease, particularly treatment of the freezing phenomenon which has not previously been cured by the conventional antiparkinsonian drugs such as L-DOPA.
Abstract: A method for treating peripheral orthostatic hypotension which comprises administering DL- or L-threo-3,4-dihydroxyphenylserine or a pharmaceutically acceptable acid addition salt thereof to a subject suffering from the disease. The composition may be administered either orally or parenterally.