A 52-year-old woman developed right upper and lower limb pain with mild tremor (more pronounced at rest) 2 years ago after IV fluids for high fever lasting 7-8 days. Over the past 3 months, left limb tremor appeared, worsened by emotional stress but disappearing during sleep, accompanied by limb stiffness and small-step gait. Examination: masked facies, drooling from the corner of the mouth, generalized tremor, lead-pipe muscle rigidity, head forward tilt, and bradykinesia. Brain MRI was normal. Which of the following drugs should NOT be used in pharmacotherapy?