Management

Atropine was used as the sole treatment until the enzyme-specific antidote pralidoxime chloride (Protopam, 2-PAM, a relatively nontoxic substance) was developed and is still used as the sole treatment in developing countries. In the United States, the standard protocol calls for the use of pralidoxime in mild cases and coadministration of pralidoxime and atropine in moderate and severe poisonings. In cases of oral ingestion, activated charcoal in suspension may be used if the patient is seen within 30 minutes of ingestion (Table 23.6) (56)

Table 23.6. Medications useful in management of toxicity associated with agricultural exposure.

Drug

Adult dosage

Contraindications

Interactions

Pregnancy

Complications and adverse effects

Dimercaprol (BAL suspension in peanut oil)

0.5-3 mg/kg q4h IM for 2 d, then q.i.d. for 1 d followed by b.i.d. for 10 d. Higher doses may be needed. Maximum dose is 5 mg/kg

Documented hypersensitivity; hypersensitivity to peanuts; G-6-PD deficiency; concurrent iron supplementation therapy

Selenium, uranium, iron, or cadmium may increase toxicity

Class C—Safety for use during pregnancy has not been established

Fever, tachycardia, hypertension, headache, CNS stimulation, nausea and vomiting.

Sterile abscess may develop at injection site.

May induce hemolysis in G-6-PD-deficient patients

Succimer (Chemet)

PO dose 10 mg/kg q8h x 5 d; 10 mg/kg q12h x14d

Documented hypersensitivity

Do not administer concomitantly with edetate calcium disodium or penicillamine

Class B—Usually safe but benefits must outweigh the risks

Excreted via kidneys, adequate hydration must be maintained; patients with renal insufficiency should be treated with caution. Not the 1st choice in arsenic poisoning.

Watch for nausea/vomiting, thrombocytopenia, eosinophilia, and cardiac dysrhythmias.

Penicillamine (Cuprimine, Depen)

25 mg/kg PO, q6h to maximum 1 g/d

Documented hypersensitivity

Increases effects of immunosuppressants, phenylbutazone, and antimalarials; decreases digoxin effects zinc salts, antacids, and iron may decrease effects

Class B—Usually safe but benefits must outweigh the risks

Nausea, vomiting, fever, rash, neutropenia, thrombocytopenia, eosinophilia, and Stevens-Johnson reaction

continued continued

Table 23.6. Medications useful in management of toxicity associated with agricultural exposure. (continued)

Drug

Adult dosage

Contraindications

Interactions

Pregnancy

Complications and adverse effects

Atropine (Atropair)

1 mg IV (initial or

Documented

Coadministration with

Class C—Safety for

Caution in patients with (1)

diagnostic) 2-4 mg

hypersensitivity;

other anticholinergics

use during

brain damage to prevent

IV q15min

thyrotoxicosis,

have additive effects;

pregnancy has

hyperreactive response;

(therapeutic). Also,

narrow-angle

pharmacologic effects

not been

(2) coronary heart disease,

2 mg/kg/h IV drip

glaucoma, and

of atenolol and

established

congestive heart failure,

as needed to control

tachycardia

digoxin may increase;

cardiac arrhythmias, and

secretions

antipsychotic effects

hypertension; (3) peritonitis,

of phenothiazines

ulcerative colitis, hepatic

may decrease;

disease, and reflux

antidepressants with

esophagitis; (4) prostatic

anticholinergic

hypertrophy.

activity may increase

effects of atropine

Pralidoxime

1-2 g IV over 15 min

Documented

None reported

Class C—Safety for

Relatively nontoxic

(2-PAM,

initial; followed

hypersensitivity

use during

compounds; not effective

Protopam)

by 500 mg/h IV

pregnancy has

for poisonings caused by

until improved

not been

organophosphates without

muscle strength

established

anticholinesterase activity.

Source: Data from Jeyaratnam and Maroni (56).

Source: Data from Jeyaratnam and Maroni (56).

Aggressive and timely therapy usually leads to recovery from acute toxicity within 10 to 14 days. Delayed intervention or chronic exposure may lead to impaired recovery and possible permanent neurological sequelae. Such sequelae may lead to delayed fatalities as observed after the 1995 Tokyo terrorist attack (56).

Acute poisoning does not warrant extensive imaging or electrophysiologi-cal studies, as they may contribute little new information in a typical case. Of course, any focal deficit must be investigated as aggressively as the case warrants and local conditions would allow. Both NCS and EMG are helpful and should be repeated on a regular basis (every 9 to 12 months) in cases of pesticide-induced neuropathies and, somewhat surprisingly, also in patients who require mechanical ventilation. Singh et al. (44) examined the phrenic nerve conduction of 29 patients with organophosphate toxicity admitted to the hospital in 1997, 14 of whom required mechanical ventilation. They found that the reduction in compound muscle action potential (CMAP) correlated with the need for ventilatory assistance. By following patients with daily nerve conduction studies, the authors were able to predict successful weaning.

0 0

Post a comment