Disclosed herein are arginine salts of carbidopa and levodopa and compositions that include for example the arginine salt of carbidopa suitable for continuous administration for treating neurological or movement diseases or disorders such as restless leg syndrome, Parkinson's disease, secondary parkinsonism, Huntington's disease, Parkinson's-like syndrome, PSP, MSA, ALS, Shy-Drager syndrome and conditions resulting from brain injury including carbon monoxide or manganese intoxication, together with administration of levodopa.