Pharm 101: Olanzapine

Class

Second generation antipsychotic (SGA)
Other examples include: clozapine, quetiapine, risperidone


Pharmacodynamics
  • Thienobenzodiazepine
  • Greater blockade of 5-HT-2a receptors than D2 (low D2/5-HT2A ratio)
  • Some alpha blockade and M receptor blockade
  • Effective against negative and positive symptoms
  • Clinical effects:
    • High clinical potency
    • Medium sedative action
    • Low hypotensive action
    • Very low EPS

Pharmacokinetics of antipsychotic drugs (general)
  • Characteristics of most antipsychotic drugs:
    • Readily but incompletely absorbed
    • Significant first-pass metabolism
    • Highly lipid soluble and protein bound (92-99%)
    • Large volumes of distribution (usually > 7L/kg)
    • Much longer duration of action than estimated from their plasma half-lives
    • Hepatic metabolism by oxidation or demethylation, catalysed by CYP450 enzymes

Clinical uses
  • Schizophrenia – improvement of both positive and negative symptoms
  • Bipolar disorder (adjunctive with lithium)
  • Agitation
  • Route and dosage:
    • PO, SL, IM, depot IM
    • 10-20mg

Adverse effects
  • Weight gain
  • Sedation (but less than typical antipsychotics)
  • Metabolic syndrome (diabetes, high cholesterol)
  • Dose-related lowering of seizure threshold
  • Some anticholinergic effects

Precautions
  • Elderly
  • Hepatic/renal impairment

Further reading

References

Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU (RCE, Biliary, DVT, E-FAST, AAA) Emergency Medicine Advanced Trainee in Melbourne, Australia. Special interests in diagnostic and procedural ultrasound, medical education, and ECG interpretation. Editor-in-chief of the LITFL ECG Library. Twitter: @rob_buttner

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.