Overview
This lecture covers the types, mechanisms, side effects, and nursing considerations for antipsychotic medications used to treat psychotic and other related disorders.
Indications and Administration
- Antipsychotics treat schizophrenia, acute mania, delirium, bipolar, psychosis, and obsessive-compulsive disorders.
- They are usually given orally, but some are available sublingually, transdermally, intramuscularly, intravenously, or subcutaneously.
Classes of Antipsychotics
- Antipsychotics are divided into first-generation (typical) and second-generation (atypical) categories.
- Typical antipsychotics are further classified as high-potency (e.g., haloperidol, trifluoperazine, fluphenazine) and low-potency (e.g., thioridazine, chlorpromazine).
- High-potency typicals have a higher affinity for dopamine receptors; low-potency require higher doses.
- Atypical antipsychotics (e.g., clozapine, olanzapine, quetiapine, risperidone, ziprasidone) also block serotonin 5-HT2A receptors.
Mechanism of Action
- All antipsychotics block dopamine D2 receptors in the mesolimbic pathway to reduce psychotic symptoms.
- Atypical antipsychotics additionally block serotonin receptors in the mesocortical pathway.
Side Effects and Adverse Reactions
- Non-selective dopamine blockade increases prolactin, causing galactorrhea (milk-like nipple discharge).
- Blockade in the nigrostriatal pathway leads to extrapyramidal symptoms (EPS): dystonia (muscle spasms), oculogyric crisis, akathisia (restlessness), pseudoparkinsonism (rigidity, bradykinesia, tremors).
- Tardive dyskinesia involves involuntary perioral movements and can be irreversible; drugs should be stopped at first sign.
- Neuroleptic malignant syndrome (NMS): confusion, rigidity, agitation, hyperthermia, seizures, coma; most dangerous EPS.
- Typical antipsychotics are more likely to cause EPS than atypicals.
- Blockade of muscarinic receptors causes anticholinergic side effects: dry mouth, blurred vision, urinary retention, constipation.
- Alpha-1 blockade can cause orthostatic hypotension; histamine blockade may result in sedation.
Key Terms & Definitions
- Antipsychotics — Drugs for treating psychotic and related disorders by blocking dopamine receptors.
- Typical Antipsychotics — First-generation antipsychotics, classified by potency.
- Atypical Antipsychotics — Second-generation drugs; block both dopamine and serotonin receptors.
- Extrapyramidal Symptoms (EPS) — Movement disorders from dopamine blockade in the nigrostriatal pathway.
- Tardive Dyskinesia — Irreversible, involuntary movements from long-term antipsychotic use.
- Neuroleptic Malignant Syndrome (NMS) — Life-threatening reaction with rigidity, fever, and altered mental status.
Action Items / Next Steps
- Review signs and symptoms of EPS and NMS.
- Memorize high- and low-potency typical and common atypical antipsychotics.
- Understand the different side effect profiles for typical versus atypical drugs.