The present invention provides highly stable carbidopa-based pharmaceutical compositions comprising an antioxidant combination consisting of ascorbic acid and at least one additional antioxidant, wherein said combination strongly inhibits carbidopa degradation. These compositions may further comprise levodopa and/or one or both of arginine and meglumine, and are beneficial in treatment of a disease, disorder or condition associated with loss of dopamine or dopaminergic neurons, e.g., Parkinson's disease.
