Agent 15 Poisoning Medication
- Author: Geoffrey M Fitzgerald, MD; Chief Editor: Duane C Caneva, MD, MSc more...
In the past, physostigmine was used to reverse the effects of anticholinergic intoxicants. However, numerous adverse effects from its use are reported. For this reason, its role as an antidote is controversial, and benzodiazepines generally are considered to be the safest medications for treating patients with anticholinergic-mediated agitation or delirium. Physostigmine use is reserved for patients with intractable seizures, tachycardia, or agitation. Physostigmine does not shorten the clinical course of anticholinergic toxicity. Neostigmine and pyridostigmine lack the central antimuscarinic activity needed to make them effective antidotes.
Physostigmine is a carbamate that increases the concentration of acetylcholine in synapses and neuromuscular junctions through acetylcholinesterase inhibition.
Increased concentration of acetylcholine can improve patient's delirium dramatically; for reasons that are not entirely clear, appears to have less effect if administered within 4 h postexposure.
By binding to specific receptor-sites these agents appear to potentiate effects of GABA and facilitate inhibitory GABA neurotransmission and other inhibitory transmitters.
Depresses all levels of CNS (eg, limbic and reticular formation), possibly by increasing activity of GABA.
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