Category: Pharmacology & Therapeutics
Posted: 4/27/2017 by Tu Carol Nguyen, DO
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Haloperidol has a higher D2 receptor antagonist effect than standard antiemetic treatment agents such as metoclopramide. In addition, newer antipsychotic agents such as Olanzapine have a high affinity at multiple antiemetic sites such as the dopamine and serotinergic receptors.
While formal RCT's are still in the works, multiple sources including palliative care, emergency medicine, and pain journals support their use in refractory emesis.
Consider Haloperidol 3-5 mg IV.
Check an EKG for long QTc prior to use. Consider dose reduction of haloperidol in those with hepatic impairment. Also consider dose reduction in patients taking carbamazepine, phenytoin, phenobarbital, rifampicin, or quinidine due to that pesky CYP3A4 inhibition.
Consider Olanzapine 2-5 mg IV.
Several case reports have shown a higher rate of success with olanzapine for refractory emesis. Olanzapine has similar precautions as those to haloperidol (EKG, hepatic impairment), although it's CYP drug interactions are less common. Additionally, use olanzapine cautiously in hyperglycemic patients as there are several case reports of olanzapine prompting episodes of DKA. Consider frequent blood sugar checks or small doses of insulin in hyperglycemic patients.
Take Home Points:
Consider the antipsychotic agents Haloperidol or Olanzapine for patients with refractory emesis, they may be more effective than traditional antiemetics.
Get an EKG prior to administration to check for QTc prolongation. As the classical and atypical antipsychotic agents are sedating, use caution in conjunction with other sedating medications (such as benzodiazepines).
