Atypical Antipsychotics, Tardive Dyskinesia, and D ₂ Receptors

“Mr. A,” a 53-year-old man who was diagnosed with chronic schizophrenia, had been treated with various typical antipsychotic drugs such as haloperidol, trifluoperazine, and chlorpromazine. Three years prior, while taking haloperidol (up to 30 mg/day) for 4 months, he developed tardive dyskinesia (his chief symptom being a pin-rolling movement of the fingers). Haloperidol was subsequently discontinued, and clozapine was started and increased to 400 mg/day over a 6 week-period, with complete remission of tardive dyskinesia. Three years later, while on the same dose of clozapine, the patient experienced a relapse of psychotic symptoms. Because of significant sialorrhea that limited further dose increases of clozapine, olanzapine (10 mg/day) was added. Six weeks after adding olanzapine to clozapine, Mr. A developed truncal tardive dyskinesia, manifested by repetitive rhythmic and involuntary pelvic thrusting. His score on the Abnormal Involuntary Movement Scale was 12. Olanzapine was discontinued immediately, and sequential trials with propranolol, tetrabenazine, and quetiapine (up to 200 mg/day) did not result in any improvement in the patient’s symptoms of tardive dyskinesia. However, his involuntary movements disappeared 6 months after their onset, following resumption of monotherapy with clozapine (400 mg/day).