2. Drug-induced parkinsonism—

2. Drug-induced parkinsonism—Many drugs can cause parkinsonian symptoms; these effects are usually reversible. The most important drugs are the butyrophenone and phenothiazine antipsychotic drugs, which block brain dopamine receptors. At high doses, reserpine causes similar symptoms, presumably by depleting brain dopamine. MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), a by-product of the attempted synthesis of an illicit meperidine analog, causes irreversible parkinsonism through destruction of dopaminergic neurons in the nigrostriatal tract. Treatment with type B monoamine oxidase inhibitors (MAOIs) protects against MPTP neurotoxicity in animals.