Medical Pharmacology Chapter 16: Pharmacology of Antipsychotics Drugs
First Generation Antipsychotic Medications
Tardive Dyskinesia
Tardive dyskinesia (TD) is a potentially irreversible hyperkinetic movement
disorder caused by prolonged dopamine receptor blockade.
Tardive dyskinesia is characterized by repetitive, involuntary movements most commonly affecting the orofacial region (lip smacking, tongue protrusion, chewing movements) but may also involve the trunk and extremities.
Research diagnostic criteria established by Schooler and Kane in 1982, requiring at least moderate abnormal movements in one body region or mild movements in two or more, remain the standard definition used in clinical trials.9
Kane and colleagues' 1988 comprehensive review of TD epidemiology reported annual incidence rates of 5% in adults under 40 years of age, rising to 25–30% per year in elderly patients.10
Cumulative prevalence in chronically treated patients is estimated at 20–30%.
Risk factors include: older age, female sex, early EPS, longer duration of treatment, higher cumulative FGA dose, presence of mood disorder, and history of brain injury.
Once established, TD persists in 50–75% of affected patients even after antipsychotic discontinuation.
Vesicular
monoamine transporter 2 (VMAT2) inhibitors,
valbenazine and deutetrabenazine, are now
FDA-approved for TD management and represent a
significant therapeutic advance.
Clinical Pearl: Monitoring for Tardive Dyskinesia
Use the Abnormal Involuntary Movement Scale (AIMS) at baseline and every 3–6 months during FGA therapy.
Masked TD: Extraspyramidal Syndrome (EPS) treatment with anticholinergics can suppress TD movements; they may appear or worsen upon dose reduction.
Perioral movements appearing in elderly patients are highly suggestive of TD; consider dose reduction or switch to an SGA. appearing in elderly patients are highly suggestive of TD; consider dose reduction or switch to an second-generation antipsychotic (SGA).
Per APA 2021 guidelines, patients on FGAs should receive systematic monitoring for signs of TD with a validated rating scale.
American Psychiatric Association Practice Guidelines (https://psychiatryonline.org/books/guidelines)
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