Drops, Ointments, Gels, and Patches: The Dangers of Topical Medications

Liquids

Liquid nicotine also poses a major threat to the pediatric population. Since the early 2000s, electronic cigarettes (e-cigarettes) have gained popularity. E-cigarette cartridges contain highly concentrated liquid nicotine, and, until May 2016, were not regulated by the US Food and Drug Administration (FDA).⁹ Since then, the FDA’s updated rule now extends to all tobacco products, including e-cigarettes.¹⁰

Some of the recent literature suggest oral lethal doses of nicotine occur at levels as low as 0.8 mg/kg,¹¹ though this is likely an overly conservative level. At this dose, even relatively diluted products with a 1.8% nicotine solution could be fatal.¹²

Liquid nicotine comes in thousands of flavors,¹³ and while this may make its use more enjoyable for adults, it poses a significant risk to small children. Children may be enticed to ingest liquid nicotine products due to their flavor-enhanced scents.¹²

At relatively low serum levels, nicotine acts as a nicotinic acetylcholine receptor agonist. Symptoms such as nausea, vomiting, diarrhea, abdominal discomfort, increased salivation, and weakness can occur early on in toxicity.¹³ Once nicotine concentrations reach higher levels, patients develop altered mental status, hemodynamic instability, seizure, muscle weakness, and respiratory compromise.

Treatment. Supportive therapy should be initiated when caring for patients with nicotine ingestion. Airway management is paramount, particularly if the patient has altered mental status. In some cases, intubation may be necessary, especially in patients with altered mental status and excessive salivation/bronchorrhea. Intravenous fluid administration is pivotal in patients with hypotension, particularly for those at risk for dehydration secondary to vomiting and diarrhea. Although there is no definitive antidote, atropine can be used to treat patients who are symptomatic from excessive muscarinic cholinergic stimulation.^13,14 If seizures occur, they can be treated with benzodiazepines as needed.

The use of activated charcoal has little mention in the current literature. Because of its liquid formulation, nicotine will likely be absorbed quickly. If ingestion occurred shortly prior to presentation and the patient’s airway is patent or secured, a dose of activated charcoal may be cautiously administered.¹⁵ The prognosis is poor if large amounts of liquid nicotine have been consumed.

Topical Ointments

Ointments are semisolid preparations, typically for topical application. Topical anesthetics are available in a variety of prescription and nonprescription ointments. Of the local prescription and nonprescription anesthetics currently available, amide-type local anesthetics have become especially popular for their rapid and reliable onset of local anesthesia and low occurrence of hypersensitive reactions. Increased popularity raises the likelihood of accidental ingestion—especially in pediatric patients.

Dibucaine, an amide anesthetic, is available as a nonprescription medication. Its uses include treating pain associated with external hemorrhoids and pain after episiotomy. Compared with lidocaine, dibucaine is significantly more potent, and toxicity can occur at much lower levels.¹⁶  

Therapeutically, local anesthetics act by binding to sodium channels, which are necessary for propagation of action potentials¹⁷; this blocks signal transduction in local sensory nerves. Toxicity occurs when these agents exert systemic effects, especially on the CNS and heart. Patients with toxic ingestion typically exhibit CNS effects, such as gait disturbances, visual changes, agitation, altered mental status, and seizure; mortality can occur in severe cases. At higher doses, cardiovascular effects may manifest and lead to vasodilation, hemodynamic instability, and dysrhythmias. QRS prolongation, which likely results from sodium channel blockade, can precipitate dysrhythmias; wide-complex bradycardia, ventricular tachycardia, ventricular fibrillation, and asystole have all been reported.^16,17Treatment. Supportive care, including airway management and fluid resuscitation, should be initiated as early as possible. Although not well documented in the literature, activated charcoal may be administered if there is no concern for the patency of the patient’s airway or if the airway has been secured.^16,17

Patients with clinically significant dibucaine ingestions typically exhibit the CNS findings previously described. Seizures require aggressive management because they can cause a metabolic acidosis that potentiates the toxicity of dibucaine. Benzodiazepines are good first-line agents, though pentobarbital, phenobarbital, or propofol can be used if the patient continues to seize.¹⁷

Fluid resuscitation should be maximized in hemodynamically unstable patients prior to administering vasopressors, which are often warranted if blood pressure does not respond to fluids. Evidence supports the use of lipid emulsion therapy in hemodynamically unstable patients¹⁸; several authors have reported successful resuscitation after administrating lipid emulsion to treat amide anesthetic toxicity (generally bupivacaine toxicity). Fatalities associated with dibucaine ingestion have been reported¹⁶; therefore, ingestion of any topical anesthetic must be recognized and treated promptly.

Gels

Gels are a common topical drug-delivery system. In pediatric patients, these medications are typically used to help decrease teething pain.¹⁹

Benzocaine

Benzocaine (eg, Anbesol, Oragel), an ester anesthetic, is one of the most common medications used to alleviate teething pain in infants. Though benzocaine gels possess analgesic properties at therapeutic dosing, severe toxicity can develop in cases of overdose.