Aripiprazole-induced parkinsonism

Dopamine receptor antagonism is associated not only with antipsychotic action, but also with the generation of extrapyramidal side-effects of antipsychotic medications. Positron emission tomography studies reveal that an approximate 60-70% blockade of the D₂ receptors is required for typical antipsychotics to be efficacious, but a blockade of ≥ 75-80% results in acute extrapyramidal side-effects. The newer atypical antipsychotics have a lower propensity to produce extrapyramidal side-effects. A new class of antipsychotics with a novel pharmacological profile and improved tolerability have emerged, comprising the 'dopamine-serotonin system stabilizers' of which aripiprazole is the first agent. We present the case of a patient who developed parkinsonism during treatment with aripiprazole.