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EPIDEMIOLOGY

In 2013, 2.2 million poisonings were reported to the American

Association of Poison Control Centers. Half of these exposures occur in

children younger than 5 years of age and usually involve a single

substance that is found in the home such as personal care items,

analgesics, and cleaning agents. The most common exposures in

descending order include cosmetic/personal care products, household

cleaning agents, analgesics, toys and foreign bodies, and topical

preparations.

Case 5-1 (Questions 2, 3),

Table 5-1

GENERAL MANAGEMENT

The most important aspect of patient management is to support airway,

breathing, and circulation (the “ABCs”). There is no “cookbook”

method to treat all poisoned patients, so it is important to treat the

patient, not the poison or the laboratory values. The assessment and

treatment of the potentially poisoned patient can be separated into seven

functions: (a) gather history of exposure, (b) evaluate clinical

presentation (i.e., “toxidromes”), (c) evaluate clinical laboratory patient

data, (d) remove the toxic source (e.g., irrigate eyes, decontaminate

exposed skin), (e) consider antidotes and specific treatment, (f) enhance

systemic clearance, and (g) monitor patient outcome.

Case 5-4 (Questions 1, 3, 5,

6)

GASTROINTESTINAL DECONTAMINATION

The most appropriate method for gastrointestinal (GI) tract

decontamination is unclear because sound comparative data for

different methods of GI decontamination are not available. Lavage,

emesis, and cathartics are rarely performed as there is no evidence they

improve patient outcome. Activated charcoal is generally safe to use,

but it should not be administered if the benefit is not greater than the

risk. Whole bowel irrigation using a polyethylene glycol–balanced

electrolyte solution can successfully remove substances (iron, lithium,

sustained-release dosage forms) from the entire GI tract in a period of

several hours.

Case 5-3 (Questions 6, 7),

Case 5-4 (Questions 11, 12,

16), Case 5-5 (Question 3)

ANTIDOTES

An antidote is a drug that neutralizes or reverses the toxicity of another

substance. Some antidotes displace drugs from receptor sites (e.g.,

naloxone for opioids, flumazenil for benzodiazepines), and some can

inhibit the formation of toxic metabolites (e.g., N-acetylcysteine [NAC]

for acetaminophen, fomepizole for ethylene glycol and methanol).

Case 5-4 (Questions 2, 4)

TOXICOLOGY LABORATORY SCREENING

An antidote is a drug that neutralizes or reverses the toxicity of another

substance. Some antidotes displace drugs from receptor sites (e.g.,

naloxone for opioids, flumazenil for benzodiazepines), and some can

inhibit the formation of toxic metabolites (e.g., N-acetylcysteine [NAC]

for acetaminophen, fomepizole for ethylene glycol and methanol).

Case 5-4 (Questions 2, 4)

p. 62

p. 63

TOXICOLOGY LABORATORY SCREENING

Urine drug screens can be useful in a patient with coma of unknown

etiology, when the presented history is inconsistent with clinical findings,

or when more than one drug might have been ingested. Qualitative

screening is intended to identify unknown substances involved in the

toxic exposure. A benzodiazepine screen can detect oxazepam, a

common benzodiazepine metabolite, but it will not detect alprazolam and

lorazepam as they are not metabolized to oxazepam. Opioid screens

may not detect synthetic opioids such as fentanyl and methadone.

Quantitative testing determines how much of a known drug is present

and can help determine the severity of toxicity and the need for

aggressive interventions (e.g., hemodialysis in ethylene glycol, methanol,

and salicyclate).

Case 5-4 (Questions 1, 7, 8)

TOXIDROMES

A toxidrome is a consistent constellation of signs and symptoms

associated with some specific classes of drugs. The most common

toxidromes are those associated with anticholinergic activity, increased

sympathetic activity, and central nervous system (CNS) stimulation or

depression. Anticholinergic drugs increase heart rate and body

temperature, decrease GI motility, dilate pupils, and produce drowsiness

or delirium. Sympathomimetic drugs increase CNS activity, heart rate,

body temperature, and blood pressure. Opioids, sedatives, hypnotics, and

antidepressants depress the CNS, but the specific class of CNS

depressant often cannot be easily identified.

Case 5-4 (Questions 1, 2, 5)

SALICYLATES

Acute ingestion of 150 to 300 mg/kg aspirin causes mild-to-moderate

intoxication, greater than 300 mg/kg indicates severe poisoning, and

greater than 500 mg/kg is potentially lethal. Symptoms of intoxication

include vomiting, tinnitus, delirium, tachypnea, metabolic acidosis,

respiratory alkalosis, hypokalemia, irritability, hallucinations, stupor,

coma, hyperthermia, coagulopathy, and seizures. Salicylate intoxication

Case 5-1 (Questions 1, 3),

Case 5-2 (Questions 1–6)

mimics other medical conditions and can be easily missed. Patients with

a chronic salicylate exposure, acidosis, or CNS symptoms and those

who are elderly are at high risk and should be considered for early

dialysis.

IRON

Acute elemental iron ingestions of less than 20 mg/kg are usually

nontoxic; doses of 20 to 60 mg/kg result in mild-to-moderate toxicity,

and doses of greater than 60 mg/kg are potentially fatal. Symptoms of

toxicity include nausea, vomiting, diarrhea, abdominal pain, hematemesis,

bloody stools, CNS depression, hypotension, and shock. Patients with

severe iron poisoning do not exhibit the second stage of so-called

recovery but continue to deteriorate.

Case 5-3 (Questions 1, 2–14)

TRICYCLIC ANTIDEPRESSANTS

Severe toxicity has been associated with doses of 15 to 25 mg/kg.

Symptoms include tachycardia with prolongation of the PR, QTc, and

QRS intervals, ST and T-wave changes, acidosis, seizures, coma,

hypotension, and adult respiratory distress syndrome. A QRS segment

greater than 100 milliseconds is commonly seen in severe tricyclic

antidepressant overdoses.

Case 5-4 (Questions 9–17)

ACETAMINOPHEN

Toxicity is associated with acute ingestions greater than 150 mg/kg or

more than 7.5 g total in adults. Symptoms in patients with toxicity

include vomiting, anorexia, abdominal pain, malaise, and progression to

characteristic centrilobular hepatic necrosis. Acetaminophen-induced

hepatotoxicity is universal by 36 hours after ingestion, but patients who

receive NAC within 8 to 10 hours after ingestion rarely exhibit

hepatotoxicity. There is no consensus as to the best route of NAC

administration, the optimal dosage regimen, or the optimal duration of

therapy.

Case 5-5 (Questions 1–15)

p. 63

p. 64

This chapter reviews common strategies for the evaluation and management of drug

overdoses and poisonings. Information for the management of specific drug

overdoses is best obtained from a poison control center (reached by calling 1-800-

222-1222 anywhere in the United States).

Epidemiologic Data

AMERICAN ASSOCIATION OF POISON CONTROL CENTERS AND

DRUG ABUSE WARNING NETWORK

Toxicity secondary to drug and chemical exposure commonly occurs in children. The

incidence of exposure to specific agents and the severity of outcomes varies based on

the population studied (Table 5-1).

1–3 The number of reported toxic exposures in the

United States in 2013 was approximately 2.2 million, according to the American

Association of Poison Control Centers (AAPCC).

3 Approximately 70% of the

reported cases were treated at home, saving millions of dollars in medical costs.

According to the Drug Abuse Warning Network, almost 5.1 million US emergency

department (ED) visits involved drug misuse or abuse in the year 2011. Illicit drugs

include cocaine, heroin, marijuana, ecstasy, gamma-hydroxyutyric acid,

flunitrazepam (Rohypnol), ketamine, lysergic acid, phencyclidine, and hallucinogens.

Of those cases, illicit drug use was mentioned more than 2.7 million times because

many of the visits involved multiple drugs of abuse.

4

AGE-SPECIFIC DATA

Stratifying patients by age can be useful in assessing the likelihood of severe toxicity

from an exposure. Most unintentional ingestions by children 1 to 6 years of age occur

because children are curious, becoming more mobile, and beginning to explore their

surroundings, and they often put objects or substances into their mouths.

5 Severe

toxicity in young children is relatively uncommon as exposures usually involve the

ingestion of relatively small amounts of a single substance.

5,6 AAPCC epidemiologic

data also report medication errors, which in the pediatric population commonly

result from confusing units of measurement (e.g., teaspoons vs. milliliters or

tablespoons vs. teaspoons), incorrect formulation or concentration administered,

dispensing cup errors, and incorrect formulation or concentration dispensed from the

pharmacy.

3

In children older than 6 years of age, the reasons for toxic exposure to medications

are less clear.

7 Adolescent children generally have poor knowledge of the toxicity of

medications and can overdose themselves unintentionally.

5,8 The potential for suicide

attempts or intentional substance abuse should not be ignored in older children.

These intentional overdoses commonly involve mixed exposures to illicit drugs,

prescribed medications, or ethanol and are associated with more severe toxicity and

death than unintentional toxic exposures.

In geriatric patients, overdoses tend to have a greater potential for severe adverse

effects compared with overdoses in other age groups.

9 Although the elderly constitute

13% of the population, they account for 33% of the drug use and 16% of the

suicides.

10 Patients aged 65 or older take an average of 5.7 prescription medications

along with 2 to 4 nonprescription drugs daily.

9,10 The elderly are more likely to have

underlying illnesses and often have access to a variety of potentially dangerous

medications. This results in higher rates of completed suicides than in other age

groups.

10,11

Information Resources

COMPUTERIZED DATABASES

A vast number of substances can be involved in a poisoning or overdose. Reliable

data about the contents of products, toxicities of substances, and treatment

approaches need to be readily accessible. POISINDEX, a computerized database,

11

provides information on thousands of drugs by brand name, generic name, and street

name, as well as foreign drugs, chemicals, pesticides, household products, personal

care items, cleaning products, poisonous insects, poisonous snakes, and poisonous

plants. Annual subscriptions to POISINDEX, updated quarterly, are expensive and

are generally available only in large medical centers.

12

Table 5-1

Substances Most Commonly Involved in Poisonings

a

Children Adults Fatal Exposures (All Ages)

Personal care products Analgesics Sedatives/hypnotics/antipsychotics

Cleaning substances Sedatives/hypnotics/antipsychotics Cardiovascular agents

Analgesics Antidepressants Opioids

Topical products Cardiovascular agents Stimulants

Vitamins Cleaning substances Alcohols, acetaminophen-containing

products

Antihistamines Alcohols Acetaminophen

Pesticides Pesticides Fumes/gases/vapors

Cough and cold products Bites, envenomations Antidepressants

Plants Antiepileptic agents Antihistamines

GI products Personal care products Tricyclic antidepressants, aspirin

Antimicrobials Antihistamines Muscle relaxants

Cardiovascular Hormones and hormone antagonists Antiepileptic agents

Arts and office supplies Hydrocarbons Nonsteroidal anti-inflammatory drugs

Hormones and hormone antagonists Antimicrobials

Alcohols Chemicals

Fumes/gases/vapors

aPoisoning exposures are listed in order of frequency encountered.

GI, gastrointestinal.

Source: Mowry et al. 2013 Annual report of the American Association of Poison Control Centers’ National Poison

Data System (NPDS): 31st Annual Report. Clin Toxicol (Phila). 2014;S2:1032.

p. 64

p. 65

PRINTED PUBLICATIONS

Textbooks and manuals also provide useful clinical information about the

presentation, assessment, and treatment of toxicities. Goldfrank’s Toxicologic

Emergencies

13 and the pocket-size Poisoning & Drug Overdose

14 are valuable, lessexpensive alternatives to computerized database programs. Books, however, are less

useful than computerized databases because information must be condensed and

cannot be updated as frequently. Some drug package inserts also refer to treatment of

acute toxicities; however, the information can be inadequate or inappropriate.

15,16

POISON CONTROL CENTERS

Poison control centers provide the most cost-effective and accurate information to

health care providers and to the general public.

17,18 Poison centers are staffed by

trained poison information specialists who have a pharmacy, nursing, or medical

background. Physician backup is provided 24 hours a day by board-certified medical

toxicologists. The nonphysician clinical toxicologists, pharmacists, and nurses who

staff poison control centers are certified as specialists in poison information by the

AAPCC or as clinical toxicologists by the American Board of Applied Toxicology.

19

The poison information specialist must accurately and efficiently assess eventspecific toxicity by telephone, without the benefit of direct observation of the patient.

The specialist must communicate this assessment along with treatment information

quickly, accurately, and professionally in a reassuring manner. Subsequent to

telephone consultations, poison control center staff should initiate follow-up calls to

determine the effectiveness of the recommended treatment and the need for additional

evaluation or treatment.

20,21

EFFECTIVE COMMUNICATION

Effective communication is essential to the assessment of potential poisonings. In

most situations, the person seeking guidance on the management of a potentially toxic

exposure is the parent of a small child who may have ingested a substance. The caller

is usually anxious about the child and may feel guilty about the exposure. To calm the

caller, the health care provider should quickly reassure the individual that

telephoning for help was appropriate and that the best assistance possible will be

provided.

21

If English is not the first language of the caller, or if there are other

communication barriers (e.g., panic), solutions must be found to enhance outcomes.

Most poison centers subscribe to translation services or have bilingual staff to

communicate with non–English-speaking callers. Poison centers also have special

equipment to serve the hearing- and speech-impaired populations.