CBRNE - Nerve Agents, Binary - GB2, VX2 Medication

Updated: Dec 18, 2018
  • Author: Larissa I Velez-Daubon, MD; Chief Editor: Duane C Caneva, MD, MSc  more...
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Medication

Medication Summary

Table 3 summarizes the different agents used to treat patients with nerve agent poisoning. Table 4 provides some general treatment guidelines.

All but the mildest exposures cause some degree of respiratory compromise. For this reason, oxygen should be readily available. Most of these symptoms are the result of bronchorrhea and bronchoconstriction and improve after appropriate administration of antidotes. Ventilatory support may be needed for severely poisoned patients because of respiratory muscle paralysis. Oxygen is supplied via nasal cannula, face mask, or nonrebreather mask. Remember that inspired oxygen concentrations of 50-100% carry a substantial risk of lung damage when used for more than a few hours.

Table 3. Drugs Used to Treat Patients With Nerve Agent Poisoning* (Open Table in a new window)

Drug

Dose (Adult)

Route

Indications

Contraindications

Atropine

2 mg q5-10min prn

Note: The MARK 1 kit contains 2 mg of atropine.

IV/IM/ETT

Excessive muscarinic symptoms

Relative: IV route in hypoxia has been associated with ventricular fibrillation.

Pralidoxime chloride (Protopam, 2-PAM)

15-25 mg/kg over 20 min; can be repeated after 1 h

Note: The MARK 1 kit contains 600 mg of pralidoxime.

IV/IM

Symptomatic nerve agent poisoning

Rapid infusion may result in hypertension; may worsen symptoms in carbamate poisoning

Diazepam (Valium)

2-5 mg IV

10 mg IM

IV/IM

Moderate or severe signs of poisoning, seizures

None

*Adapted from Sidell, 1992. [6]

Table 4. Summary of Treatment Modalities According to Severity of Exposure* (Open Table in a new window)

Severity/Route of Exposure

Atropine (Adult Dose)

Pralidoxime

Diazepam

Other

Suspected

No

No

No

Decontamination and 18-h observation for liquid exposures

Mild

2 mg for severe

rhinorrhea or

dyspnea; may be

repeated

Administer if dyspnea

is not improving

or if GI

symptoms occur

No

Decontamination and 18-h observation for liquid exposures; oxygen

Moderate

6 mg; may need to repeat

Administer with atropine

Administer even in absence of seizures

Decontamination; oxygen

Severe

Start with 6 mg; may need to repeat

Administer with atropine; should repeat once or twice

Administer even in absence of seizures

Airway, breathing, and circulation; decontamination

*Adapted from Sidell, 1992. [6]

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Anticholinergic agents

Class Summary

These agents antagonize ACh at the muscarinic receptor.

Atropine IV/IM (Isopto, Atropair, Atropisol)

Antagonizes ACh at muscarinic receptor, leaving nicotinic receptors unaffected. In contrast to organophosphate insecticides, nerve agents rarely require >20 mg. Continue administration until excess muscarinic symptoms improve, which can be gauged by increased ease of breathing in the conscious patient or improvement in ease of ventilation in the intubated patient.

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Oximes

Class Summary

These reactivators of AChE enzyme are generally divided into 2 groups, monopyridinium and bispyridinium types. Pralidoxime belongs to the monopyridinium group and is the oxime used in the United States. Oximes should be administered concomitantly with atropine. After aging occurs, the usefulness of pralidoxime is minimal. VX has a slow aging process (estimated at 48 h); thus, delayed treatment with oximes may be beneficial. In contrast, aging half-life for GD is only 2-6 min, which makes pralidoxime impractical in this type of exposure.

A subset of the bispyridinium oximes termed H oximes (H for Hagedorn) contains variations of conventional extant oximes. These include agents such as HI-6, HGG-12, and HGG-42. They have been studied in the military setting but are not available for use in the United States. H oximes have shown promise in reactivating aged enzyme after GD exposure. The bispyridinium oxime termed obidoxime (Toxogonin) has been successfully tested for GB and GA intoxication. Pralidoxime is ineffective in GA.

In most cases, the specific agent involved is unknown. Do not delay or withhold antidote use while awaiting agent identification. The empiric use of pralidoxime is encouraged to prevent aging of the nerve agent with the AChE.

Pralidoxime (Protopam)

Oximes are reactivators of AChE. Can be used IM (as with military autoinjectors) or IV. The IV route is more likely to be practical in ED setting. The half-life of pralidoxime is 1 h, and it is renally excreted.

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Benzodiazepines

Class Summary

Seizures can be observed in severe nerve agent poisoning. For this reason, treatment with benzodiazepines has been advocated as part of the antidotal armamentarium. Experts advocate use of benzodiazepines prophylactically in patients with moderate-to-severe poisoning as well as with patients who are actively seizing. Dose should be 2-5 mg IV or 10 mg IM. With active seizures, diazepam should be titrated to effect.

Diazepam (Valium, Diazemuls, Diastat)

Belongs to benzodiazepine family, members of which act by stimulating GABA (the main inhibitory neurotransmitter in CNS) receptors, resulting in sedation and increased seizure threshold.

Midazolam (Versed)

Used as alternative in termination of refractory status epilepticus. Because midazolam is water soluble, it takes approximately 3 times longer than diazepam to reach peak EEG effects. Wait 2-3 min to fully evaluate sedative effects before initiating procedure or repeating dose.

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