Medication Summary
Medical therapy consists of anticonvulsants, antitachydysrhythmics, sodium bicarbonate, physostigmine, and sedatives. The standard dose of physostigmine is 0.5-2 mg, given by slow iintravenous push (not to exceed 1 mg/min). However, because higher doses of physostigmine can lead to cholinergic toxicity (eg, seizures, cardiotoxic effects), Dawson and Buckley recommend giving a titrated dose of 0.5 to 1 mg in adults and waiting at least 10-15 min before re-dosing. [14]
GI decontaminant
Class Summary
Empirically used to minimize systemic absorption of the toxin.
Activated charcoal (Liqui-Char)
Most useful if administered within 4 h of ingestion. Repeat doses may be used, especially with ingestion of sustained release agents. Limited outcome studies exist, especially when administration is more than 1 h of ingestion.
Administration of charcoal by itself (in aqueous solution), as opposed to coadministration with a cathartic is becoming the current practice standard; this is because studies have not shown benefit from cathartics and, while most drugs and toxins are absorbed within 30-90 min, laxatives take hours to work. Also, dangerous fluid and electrolyte shifts have occurred when cathartics are used in small children.
When ingested dose is known, charcoal may be given at 10 times ingested dose of agent over 1 or 2 doses.
Benzodiazepines and other sedatives
Class Summary
For patients with agitation or psychosis, verbal reassurance and a quiet dimly lit room may be effective. When pharmacological intervention is required, control of agitation may be achieved with the administration of physostigmine or benzodiazepines (DOC). Treat seizures initially with benzodiazepines.
Diazepam (Valium)
Depresses all levels of CNS (eg, limbic and reticular formation), possibly by increasing activity of GABA.
Lorazepam (Ativan)
Sedative hypnotic with short onset of effects and relatively long half-life.
By increasing the action of GABA, which is a major inhibitory neurotransmitter in the brain, may depress all levels of CNS, including limbic and reticular formation.
Monitoring patient's blood pressure after administering dose is important. Adjust prn.
Phenobarbital (Luminal)
Used for patients refractory to diazepam or lorazepam.
Midazolam (Versed)
Used as alternative in termination of refractory status epilepticus. Because water soluble, takes approximately 3 times longer than diazepam to peak EEG effects. Thus, clinician must wait 2-3 min to fully evaluate sedative effects before initiating procedure or repeating dose. Has twice the affinity for benzodiazepine receptors than diazepam. May be administered IM if unable to obtain vascular access.
Cardiovascular agents
Class Summary
Used only when patient is diagnosed with tricyclic antidepressant overdose or when evidence of sodium channel blockade is present. Routine use is not recommended.
Sodium bicarbonate
Anecdotally, has been effective in treating antihistamine induced QRS prolongation (>100 ms) with a quinidinelike ECG pattern.
Cholinergic agents
Class Summary
Reversible anticholinesterase inhibitor that increases the concentration of ACh at the sites of cholinergic neurotransmission. Readily crosses the blood-brain barrier to produce desired CNS effects.
Physostigmine (Antilirium)
Inhibits destruction of acetylcholine by acetylcholinesterase, which facilitates transmission of impulses across myoneural junction.
Clinical effects last 20-60 min. Repeat prn.
