Management of Acute Poisoning From Medication Ingestion Reviewed

From Medscape Medical News
Laurie Barclay, MD

February 8, 2010 — Family physicians should be familiar with treatment of accidental and intentional medication ingestions, according to a review of the management of acute poisoning caused by medication ingestion published in the February 1 issue of American Family Physician.

"Poisoning from medications can happen for a variety of reasons, including intentional overdose, inadvertently taking an extra dose, dispensing or measuring errors, and exposure through breast milk," write Ivar L. Frithsen, MD, and William M. Simpson, Jr, MD, from Medical University of South Carolina in Charleston.

"The most common medication poisonings in adults (in order of prevalence) include analgesics; sedatives, hypnotics, and antipsychotics; antidepressants; cardiovascular drugs; anticonvulsants; antihistamines; hormones and hormone antagonists; antimicrobials; stimulants and illicit drugs; cough and cold preparations; muscle relaxants; topical preparations; gastrointestinal preparations; and miscellaneous drugs," Drs. Frithsen and Simpson write. "The most common medication poisonings in children (in order of prevalence) include analgesics; topical preparations; cough and cold preparations; vitamins; antihistamines; gastrointestinal preparations; antimicrobials; hormones and hormone antagonists; electrolytes and minerals; cardiovascular drugs; dietary supplements, herbal medications, and homeopathic medications; asthma therapies; antidepressants; and sedatives, hypnotics, and antipsychotics."

In the United States, several million episodes of poisoning are reported each year, causing significant morbidity and mortality rates. Nearly one half of all poisonings reported in the United States are attributed to acute medication poisonings, which should be considered in patients with an acute change in mental status.

Steps in Treatment of Poisoning

The first steps in treatment of a patient who has been poisoned are to evaluate the airway, breathing, and circulation, and to perform a complete history. Poisoning with drugs from certain classes, notably anticholinergics, cholinergics, opioids, and sympathomimetics, are associated with constellations of symptoms known as toxidromes. For example, anticholinergic poisoning is associated with delirium; hyperthermia; ileus; mydriasis; tachycardia; urinary retention; and warm and dry skin.

For identification of electrolyte imbalances and/or impairment of liver and renal function, basic laboratory studies, such as a complete metabolic profile, are an important part of the workup for possible medication poisonings. Clinical presentation and history should help determine what other laboratory studies are indicated.

Unless a specific antidote is available, management is supportive in most cases, because less than 1% of poisonings are fatal. Although single-dose activated charcoal is the preferred modality of gastrointestinal tract decontamination, it should not be used in all patients. The review includes specific therapies for acute medication poisoning based on the type of drug ingested.

For unstable patients who have ingested toxic medications, ongoing treatment should aim to correct hypoxia and acidosis and to maintain adequate circulation. Even when these patients appear to be compensating, their mental or hemodynamic status may deteriorate rapidly. Children are particularly susceptible to profound effects from even small amounts of medication.

Multiple factors, including pharmacokinetics of the ingested substance and the ability to be monitored in the home environment, must be considered in the disposition of a person who has been poisoned. Longer monitoring is required for patients with signs or symptoms of toxicity. For patients who have attempted suicide, psychiatric evaluation and often psychiatric hospitalization are indicated. Counseling referral is recommended for patients with evidence of substance abuse.

Key Recommendations

Specific key clinical recommendations for practice, and their accompanying level of evidence rating, are as follows:

For most medication ingestions, single-dose activated charcoal is the modality of choice for gastrointestinal decontamination. This treatment can generally be used up to 1 hour after ingestion of a potentially toxic amount of medication (level of evidence, C).
There is no indication for using ipecac syrup in a healthcare setting (level of evidence, C).
"For unstable patients, admission to an intensive care unit is appropriate, and transfer to a tertiary care facility should be considered, especially with children," the review authors conclude. "For stable patients, the amount of observation time is based on the half-life of a medication, the amount ingested, and the formulation. Any patient who develops signs or symptoms of toxicity that do not reverse during the observation period should be admitted for further observation."

The review authors have disclosed no relevant financial relationships.

Am Fam Physician. 2010;81:316-323. Abstract