Disclosed is a pharmaceutical composition comprising i) a dopamine agonist and ii) a L-DOPA derivative in combination in form of a liquid preparation. The pharmaceutical composition is used for the treatment of Parkinson's disease, restless leg syndrome, dystonia, for inhibiting prolactin secretion, for stimulating the release of growth hormones, for the treatment of neurological symptoms of chronic manganese intoxication, oamyotrophic lateral sclerosis, and multiple system atrophy.