Olanzapine

PHARMACOLOGY

Atypical antipsychotic. Dopamine-receptor and 5HT2Areceptor antagonist. Compared with typical antipsychotics (e.g. haloperidol) the incidence of drug-induced movement disorders is less. It is used in palliative care for delirium and nausea. Tablets and dispersible tablets exist.

Onset of action: hours to days
Duration of action: 12-48 h (sometimes longer)
Plasma ½ life: 34 h

DOSING

  • Agitation: 2.5 mg HS and prn PO (increase if necessary to 5-10 mg)
  • Anti-emetic: 1.25-2.5 mg HS and q2h prn PO (increase to 5 mg HS PO if necessary)

UNWANTED EFFECTS

  • Sedation
  • Weight gain
  • Hypotension
  • Dry mouth
  • Constipation
  • Agitation
  • Peripheral oedema
  • Lightheadedness

PITFALLS/CONCERNS

  • May cause orthostatic hypotension
  • Should not be used in Parkinson’s disease
  • Watch for extrapyramidal effects (EPS). If present decrease or discontinue and treat EPS symptoms using anticholinergics (benztropine), beta-blockers or benzodiazepines if necessary
  • Drug interactions exist
  • Increased risk of cerebrovascular adverse events and death in elderly patients with dementia

NOTE

This information is drawn from a number of sources (see below). The reader is encouraged to access these and other relevant literature for more detail. As always, sound clinical judgment should be used in individual clinical cases. In particular, it should be remembered that there may be significant variation in the pharmokinetics of a drug resulting from a number of factors, including the individual patient’s metabolism/disease status and how the medication has been formulated.

SOURCES/REFERENCES

  1. Brunton LL, Lazo JS, Parker KL, editors. Goodman and Gilman’s: the pharmacological basis of therapeutics. 11th ed. McGraw-Hill Professional; 2006.
  2. Twycross R, Wilcock A. Palliative care formulary. 3rd ed. Radcliffe Medical Press Ltd; 2008.
  3. Repchinsky C, editor. Compendium of pharmaceuticals and specialties (CPS): the Canadian drug reference for health professionals. 44th ed. Canadian Pharmacists Association; 2009.
  4. Goldman A, Hain R, Liben S. Oxford textbook of palliative care for children. 1st ed. Oxford University Press; 2006.

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