Outcomes of benzonatate exposures reported to a single United States poison center: a 20-year review.

Background: Benzonatate is an antitussive with sodium channel blocking properties that may cause seizures, dysrhythmias, and death in overdose. Limited data describe the medical outcomes of benzonatate exposures, and no standard treatment guidelines exist for managing benzonatate toxicity. We characterized clinical outcomes and management of benzonatate exposures over a 20-year period at the Wisconsin Poison Center.

Methods: This retrospective case review examined all benzonatate exposures reported to a single regional poison center from January 1, 2000 through December 31, 2019. Exposures were excluded if the medical record was incomplete. The primary outcome was the rate of serious adverse effects, defined as seizure, electrocardiogram changes, coma or central nervous system depression, or death. Potential life-saving treatments (antiepileptics, antidysrhythmics, vasopressors, sodium bicarbonate, or intravenous lipid therapy) were also assessed.

Results: A total of 313 calls were received with 48 exposures excluded, leaving 265 exposures included for analysis. Most exposures were female (162/265; 61%) with a median age of 19 years (IQR: 4-39 years). Sixteen exposures were adverse reactions only. Of intentional exposures (106/265; 40%), 23 (22%) experienced at least one serious adverse effect and 40 (38%) were hospitalized. Of unintentional exposures (143/265, 54%), one (0.7%) experienced a serious adverse effect and three (2%) were hospitalized. Regarding 77 unintentional pediatric exposures, none experienced a serious adverse effect, with two (2/77; 3%) hospitalized. Two deaths (0.8%) occurred during the study period; both were intentional exposures.

Discussion: While severe outcomes are possible after intentional exposures, unintentional exposures rarely exhibited serious toxicities. No therapeutic interventions beyond supportive care were consistently employed.

Conclusions: Intentional exposures to benzonatate more commonly warranted significant therapeutic interventions and caused a higher incidence of serious toxicity. Unintentional exposures did not result in clinically significant adverse effects. Although benzonatate can result in serious toxicity, adults with unintentional exposures may be candidates for home management.