Antipsychotic toxicity: Difference between revisions
Elcatracho (talk | contribs) |
(Add MedicationDose entries for magnesium sulfate, diphenhydramine, benztropine) |
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**No orthostatic hypotension | **No orthostatic hypotension | ||
**Normal QT interval | **Normal QT interval | ||
==Medication Dosing== | |||
{{MedicationDose | |||
| drug = Magnesium sulfate | |||
| dose = 2-4g IV over 10 min | |||
| route = IV | |||
| context = QTc >500ms | |||
| indication = Antipsychotic toxicity | |||
| population = Adult | |||
}} | |||
{{MedicationDose | |||
| drug = Diphenhydramine | |||
| dose = 25-50mg IV/IM | |||
| route = IV/IM | |||
| context = Dystonic reaction | |||
| indication = Antipsychotic toxicity | |||
| population = Adult | |||
}} | |||
{{MedicationDose | |||
| drug = Benztropine | |||
| dose = 1-2mg IV/IM | |||
| route = IV/IM | |||
| context = Dystonic reaction, alternative | |||
| indication = Antipsychotic toxicity | |||
| population = Adult | |||
}} | |||
==See Also== | ==See Also== | ||
Latest revision as of 21:17, 20 March 2026
Background
- Isolated overdose of antipsychotics is rarely fatal
- Toxicity results in blockade of some or all of the following receptors:
- Dopamine - extrapyramidal symptoms
- α-1 - orthostatic hypotension, reflex tachycardia
- Muscarinic - anticholinergic symptoms
- Histamine - sedation
Clinical Features
- Extrapyramidal
- Acute dystonic reaction
- Tongue protrusion, facial grimacing, trismus, oculogyric crisis
- Akathisia
- Acute dystonic reaction
- CNS
- Lethargy, ataxia, dyarthria, confusion, coma
- Seizure (1%)
- Anticholinergic Effects
- Tachycardia, dry mucous membranes, dry skin, decreased bowel sounds, delirium
- ECG changes
- Sinus tachycardia
- QT prolongation
Differential Diagnosis
Anticholinergic toxicity Causes
- Medications[1]
- Atropine
- Antihistamines
- Antidepressants
- Antipsychotics
- Muscle relaxants
- Anti-Parkinsonians
- Plants
- Jimson weed (Devil's trumpet)
- Amanita mushroom
Evaluation
Workup
- POC Glucose
- ECG (QT interval)
- Co-ingestions: serum acetaminophen, salicylate, EtOH level, other known drug levels
- Urine toxicology screen
- Chemistry (metabolic acidosis, electrolytes, renal function)
- LFT (hepatotoxicity)
- CK (rhabdomyolysis)
- Serum osmolarity (osmolar gap)
- ABG (carboxyhemoglobin, methemoglobin)
Management
Supportive
- Hypotension
- QT prolongation
- Treat all with QTc >500ms with magnesium 2-4gm IV over 10min
Extrapyramidal
- Diphenhydramine 25-50mg IV/IM OR benztropine 1-2mg IV/IM
- Oral therapy with either of above meds should be continued for 2 weeks
Disposition
- Consider discharge after 6hr as long as there are all of the following:
- No mental status changes
- Normal HR/BP
- No orthostatic hypotension
- Normal QT interval
Medication Dosing
Magnesium sulfate 2-4g IV over 10 min IV Diphenhydramine 25-50mg IV/IM IV/IM Benztropine 1-2mg IV/IM IV/IM
See Also
- Antipsychotics
- Toxicology (main)
- Neuroleptic Malignant Syndrome (NMS)
- Tardive dyskinesia
- Beta-Blocker Toxicity
- Calcium Channel Blocker Toxicity
- Extrapyramidal reaction
External Links
References
- ↑ Dawson AH, Buckley NA. Pharmacological management of anticholinergic delirium – theory, evidence and practice. Br J Clin Pharmacol. 2015;81(3):516-24.