OTCs Today
Mary Warner
Most poisoning in the United States is unintentional, making prevention and treatment of such poisoning critical to public health. Poisoning exposures often occur in young children who are exploring the world around them, but unintentional poisoning also occurs often in older adults and those taking multiple medications. Home monitoring and self-care is usually adequate for poisoning exposures. However, intentional self-harm poisonings and unintentional overuse of opioids are more appropriately treated through hospitalization.
Most poisonings are a result of ingestion of a substance, but poisonings can also occur after a toxin is inhaled or contacts the skin or eyes. Consumers are often unaware of ingredients in combination nonprescription products, particularly for pain and upper respiratory tract relief, making these combination products a common source of overdose. Misuse of acetaminophen is a major cause of both unintentional and intentional poisonings reported to U.S. poison centers.
Signs and symptoms of poisoning are often similar to the adverse effects associated with therapeutic use, such as nausea, vomiting, and abdominal pain for an ibuprofen overdose and sedation or stimulation for patients who overdose with diphenhydramine. It’s important to remember that a lack of symptoms an hour or less after a poison exposure is typical and does not preclude toxicity. In addition, ingestion of some sustained release or enteric-coated products can result in delayed symptoms of toxicity. Other medications, such as acetaminophen, metabolize to toxic metabolites, delaying symptoms that can be seen up to 5 days later.
Treating poisoning episodes
The first step in treating any poisoning episode is to contact the online resource poisonhelp.org, the official site of America’s Poison Centers, representing the nation’s 55 poison centers in partnership with CDC, FDA, and the Health Resources and Service Administration.
This website contains valuable resources for evaluating the situation, along with links to contact the poison center by phone. Poison centers are staffed around the clock with pharmacists, nurses, physicians, and physician assistants who have additional training in clinical toxicology and are available for consultation.
Most unintentional poison exposures can be self-treated, though seeking advice from the nearest poison center is always advised before any treatment. When treating a potential poisoning episode, the goal is to prevent absorption of the toxin or stem progression of toxicity. Many exposures are actually nontoxic or minimally toxic, either because the substance has very low inherent toxicity or the amount consumed is too low to cause toxicity. Patients with any inadvertent exposure to a toxin that could result in moderate to severe toxicity, as well as all patients with intentional exposures, should be referred immediately to a hospital.
Once self-care has been determined to be appropriate, treatment can be initiated. Inhalation exposures are managed by moving the patient from toxic fumes to fresh air, while exposed skin should be washed with soap and water (usually twice) to decrease the contact time with the toxin. Irrigation of eyes with water should be initiated immediately after an exposure to a chemical or drug not intended for ocular use. If an irritating chemical has been swallowed, a small volume of fluids can be used to decrease the contact time with the mucosal surface.
Drinking a large volume of fluids after the ingestion of a drug should be discouraged because excess fluid may possibly facilitate the dissolution of a solid dosage form, thereby enhancing its absorption. Administering fluids after toxic ingestions should be recommended only for drugs strongly associated with esophageal impaction, such as bisphosphonates, or those that may cause renal injury because of dehydration, such as ibuprofen or other NSAIDs. The efficacy of vomiting to reduce drug exposure is limited.
Using activated charcoal
The adsorbent activated charcoal and the emetic ipecac syrup are the only approved agents for the self-treatment of ingested poisons. Although ipecac was considered for many years to be an important treatment for orally ingested poisons, recent studies revealed that the stomach purging produced by ipecac is far less effective at lowering total body poison concentrations than the adsorption effect of oral activated charcoal, which is effective through the entire GI tract. Ipecac is no longer available as a prescription or OTC medication and pharmacists should recommend discarding any existing supplies in the home.
Activated charcoal is a gritty, fine, insoluble powder made by pyrolysis of various organic materials. Activated charcoal has been shown to be an effective adsorbent for many commonly ingested drugs and other toxic agents. These substances become bound in the internal surface of the pores of the charcoal particle, thereby preventing their absorption. However, highly ionized substances, such as potassium and lithium, are poorly adsorbed by activated charcoal, and it does not bind well to alcohols, glycols, or cyanide. The presence of food in the GI tract may reduce the efficacy of activated charcoal.
Activated charcoal is approved by FDA for use as an emergency antidote for the treatment of poison ingestion, but home administration should never include more than one dose. Pharmacists should educate patients that activated charcoal should never be used without first consulting a poison center staff member. Patients who purchase activated charcoal for immediate use on the recommendation of a poison center should receive adequate counseling to ensure its appropriate use, including instructions on preparation. The pharmacist also should explain potential adverse effects, as well as signs and symptoms that indicate the need to seek medical attention.
What to tell your patients
Older adults should be counseled on how to manage their medications to avoid inadvertent poisoning, as polypharmacy may place them at risk for errors relating to dose, dosage regimen, and administration techniques. Educating these patients about the potential for drug–drug, drug–food, and drug–alcohol interactions is important, and they should be reminded to keep medications out of the reach of children and use a locking pill organizer if they are around young children.
Advise patients to always contact the poison center if they suspect a poison exposure and to discard any remaining ipecac they may have in their home.
For more information, see the chapter on “Poisoning” in APhA’s Handbook of Nonprescription Drugs, available in the bookstore on pharmacist.com or in APhA OTC in PharmacyLibrary (www.pharmacylibrary.com). ■