Therapeutic methods and compositions for treating movement disorders

A method of treating a movement disorder in a subject in need thereof comprising administering to the subject:

• (i) a muscarinic acetylcholine receptor inhibitor in an amount effective to treat the movement disorder, and
• (ii) a muscarinic acetylcholine receptor activator in an amount effective to reduce the frequency of at least one side effect of the muscarinic acetylcholine receptor inhibitor,
• wherein the muscarinic acetylcholine receptor inhibitor is (R)-trihexyphenidyl or a pharmaceutically acceptable salt thereof,
• wherein the muscarinic acetylcholine receptor activator is bethanechol or a pharmaceutically acceptable salt thereof, and
• wherein the subject is orally administered a pharmaceutical composition comprising the (R)-trihexyphenidyl and the bethanechol in a weight ratio of (R)-trihexyphenidyl to bethanechol of about 1:1.1 to about 1:14.