Typical Antipsychotics

Summary

Typical antipsychotics, also known as first-generation antipsychotics, are an older class of drugs that were among the first to be used to treat psychotic disorders.

These drugs are subdivided into 2 categories based on their potency in the brain. High potency drugs include haloperidol, fluphenazine, and trifluoperazine, while low-potency drugs include chlorpromazine and thioridazine.

The mechanism of typical antipsychotics involves blocking dopamine receptors in the brain.

In addition to treating psychosis, typical antipsychotics are clinically used to treat schizophrenia, where they are effective at addressing the positive symptoms, but less effective for treating negative symptoms. They are also used to treat nausea and vomiting, as well as Tourette syndrome.

Important side effects include extrapyramidal symptoms, gynecomastia, anticholinergic effects, QT prolongation, neuroleptic malignant syndrome, photosensitivity, and orthostatic hypotension.

Patients taking typical antipsychotics should be counseled to avoid alcohol. These drugs should be used with caution in patients with Parkinson's disease or glaucoma.

Key Points

• Typical Antipsychotics
  • Drug Names
    • High Potency
      • Haloperidol (Haldol)
      • Fluphenazine (Prolixin)
      • Trifluoperazine (Stelazine)
    • Low Potency
      • Chlorpromazine (Thorazine)
      • Thioridazine (Mellaril)
  • Mechanism
    • Block dopamine receptors
  • Clinical Use
    • Schizophrenia
      • Mainly treats positive symptoms
        • Positive symptoms include hallucinations, delusions, disorganized thinking
    • Nausea/Vomiting
      • Typical antipsychotics, particularly chlorpromazine, are used to treat nausea and vomiting, often associated with conditions such as chemotherapy, surgery, or certain gastrointestinal disorders.
      • Blocking dopamine receptors in the chemoreceptor trigger zone of the brain helps to alleviate nausea/vomiting
    • Treats Tourette Syndrome
    • Treats Psychosis
  • Side Effects
    • Extrapyramidal Symptoms (EPS)
      • Includes akathisia, tardive dyskinesia, parkinsonism, dystonia
    • Neuroleptic Malignant Syndrome (NMS)
      • Life threatening condition
      • Characterized by hyperthermia, autonomic dysregulation, altered mental status, and generalized muscle rigidity
      • Notify provider immediately if NMS is suspected
    • Anticholinergic Effects
      • Includes urinary retention, constipation, dry mouth, tachycardia, and blurred vision
    • Gynecomastia
      • Enlargement of male breast tissue
    • Orthostatic Hypotension
      • A sudden drop in blood pressure upon standing, causing dizziness or fainting
      • Educate patient on changing positions slowly to prevent falls
    • Photosensitivity
      • Educate patient to wear sunscreen and/or protective clothing when outdoors
    • QT Prolongation
      • Can lead to torsades de pointes, a life-threatening arrhythmia
      • Monitor ECG regularly
      • Avoid concurrent use with other medications that prolong the QT interval
      • Most common with haloperidol, although may be seen with most typical antipsychotics
  • Contraindications/Precautions
    • Use caution with parkinson's disease
      • Typical antipsychotics can exacerbate symptoms of Parkinson's disease or induce parkinsonism due to their blockade of dopamine receptors.
    • Use with caution in glaucoma
      • Typical antipsychotics can increase intraocular pressure, posing a risk for individuals with glaucoma or those predisposed to developing glaucoma
    • Avoid alcohol
      • Concurrent use of typical antipsychotics with alcohol may enhance central nervous system depression, leading to increased sedation and impaired cognitive function.