creation date: 2026-06-08 18:01
tags: Pharmacology
Antipsychotics
Background
Antipsychotics are medications used to treat (non-exhaustive):
- Schizophrenia and schizoaffective disorders
- Acute mania
- Major depressive disorder with psychotic features
- Delusion disorder
- Severe agitation
- Tourette disorder
- Borderline personality disorder
- Dementia and delirium
- Psychosis due to substance use
Classes
Typical (First Generation)
Mechanism of Action
- Dopamine (D2) receptor antagonist controls positive psychosis symptoms
Side Effects
- Extrapyramidal side effects - treated with benztropine
- Acute dystonia: muscle spasms or contractions (sudden, painful)
- Akathisia: distressing feeling of inner restlessness, urge to move
- Parkinsonism: muscle rigidity, resting tremor, bradykinesia
- Tardive dyskinesia: late-onset (months/years after taking), involuntary movement condition; commonly face, tongue, lips
- Anticholingeric effects (dry mouth, constipation, urinary retention)
- QTc prolongation, abnormal heart rhythm
- Neuroleptic malignant syndrome
Contraindications
- Use of CNS depressants (eg. barbituates, benzodiazepines, opioids)
- Concurrent anticholingeric medications use
- Severe cardiac abnormalities
- History of seizure disorder
- Narrow-angle glaucoma
- Prostatic hypertrophy
- History of ongoing tardive dyskinesia
Examples
- Chlorpromazine
- Flupenthixol
- Haloperidol
- Loxapine
- Trifluperazine
- Zuclupenthixol
Atypical (Second Generation)
Mechanism of Action
- Dopamine (D2) receptor antagonism controls positive psychosis symptoms
- Serotonin receptor antagonism controls negative symptoms
Side Effects
- Less extrapyramidal side effects
- Weight gain and metabolic syndrome
- Medication-specific; examples:
- Risperidone: dizziness, anxiety, sedation
- Paliperidone: temperature sensitivity, QTc prolongation
- Olanzapine: weight gain, increased appetitie, somnolence
Contraindications
- Use with other QTc prolongation
- Breast feeding
Examples
- Clozapine (Clozaril) - effective for refractory but adverse effects
- Olanzapine (Zyprexa)
- Risperidone (Risperdal)
- Quetiapine (Seroquel)
- Paliperidone (Invega)
- Ziprasidone (Zeldox)
- Aripiprazole (Abilify)