Take home pearls
- Toxicity from atypical antipsychotics begins within 1-2 hours of ingestion and usually peaks at about 4-6 hours, though full resolution can take up to 48 hours.
- Common symptoms includes lethargy and sedation and even coma. Tachycardia and orthostatic hypotension can also be seen, as can miosis, decreased bowel sounds and other GI symptoms.
- The most common EKG finding is sinus tachycardia, though in some cases there may be Qtc prolongation, or ST-segment changes. However, these are usually clinically insignificant
Other learning points from the case:
- Atypical antipsychotics are distributed in the brain and lungs primarily, and are metabolized by the liver
- Most typical antipsychotics have anticholinergic, anti-muscarinic, anti-alpha and anti-histamine activity, so patients may have variable presentations depending on the effect of the specific medication on these receptors
- Most symptoms related to overdose affect the CNS, and olanzapine can cause intermittent sedation and agitation. The other most common symptoms are miosis and tachycardia.
- Fortunately, most overdoses of atypical antipsychotics cause mild to moderate toxicity, and many patients will have no symptoms at all!
- High doses are more likely to be toxic and cause overdose symptoms if the patient is not already taking them regularly
- There is no known laboratory test to identify atypical antipsychotic overdose àdiagnosis must be made based on patient history and exam findings
- Management is primarily supportive – remember the ABCs!
o All patients should be on tele and get an EKG
o Close monitor of mental status and airway protection is indicated
o Fluid and pressors as needed for hypotension
o If overdose is known or identified early, a single dose of activated charcoal is also recommended
- Consider calling poison control if you suspect overdose, as they can help you anticipate complications
Pearls from a few other report tangents this morning:
- Differential for diffuse ST elevations on EKG: hyperkalemia, elevated intracranial pressure, global cardiac ischemia, pericarditis, coronary vasospasm and ventricular aneurysm.
- Differential for Osborne waves on EKG: Hypothermia (classically), but also hypercalcemia, brain injury and subarachnoid hemorrhage
- Remember when sending urine tox screens that not all hospitals automatically send methadone, and no urine tox will pick up synthetic drugs (like synthetic amphetamines r marijuana)
- Triple flexion is the response of flexing the knee, hip and ankle with foot stimulation, which is indicative of upper motor neuron injury (similar to a Babinski)
- Decorticate posturing – upper extremity abduction and lower extremity extension in response to pain, which indicates cerebral cortical dysfunction and “release” of spinal pathways
- Decerebrate posturing – Upper and lower extremity extension in response to pain as a result of dysfunction below the red nucleus ( in the midbrain somewhere, we’re not neurologists)
o Decorticate posture confers a better prognosis compared to decerebrate posturing
Mowry JB, Spyker DA, Cantilena LR Jr, et al. 2012 Annual Report of the American Association of Poison Control Centers’ National Poison Data System (NPDS): 30th Annual Report. Clin Toxicol (Phila) 2013; 51:949.