Midodrine exposure trends and outcomes reported to United States poison centers: 2000-2023.

Introduction: Midodrine is an oral alpha-1 adrenergic agonist used to treat orthostatic hypotension. Its vasoconstrictive properties can lead to hypertension and reflex bradycardia. We characterized midodrine exposures reported to United States poison centers from 2000 to 2023.

Methods: We performed a retrospective analysis of single-substance midodrine exposures reported to the National Poison Data System^®. Descriptive statistics were used to characterize temporal trends, demographics, exposure reasons, level of healthcare, and medical outcomes. National estimates of retail outpatient midodrine prescriptions during 2002-2023 were obtained from IQVIA Total Patient Tracker.

Results: The number of patients dispensed midodrine from retail pharmacies increased 695%, from 55,300 in 2002 to 439,659 in 2023. There were 1,935 midodrine exposures reported to the National Poison Data System^® from 1 January 2000 to 31 December 2023. Exposures increased 714%, from 21 calls in 2000 to 171 calls in 2023. The most common features reported were hypertension in 277 (14.3%) and bradycardia in 197 (10.2%). Therapeutic errors accounted for most cases in most age groups except adolescents aged 13-19 years, in which suspected suicide was the most commonly reported reason (50.2%). Most exposures were managed at home. Among 866 patients who sought medical care, 437 (50.5%) were treated/evaluated and released, but 115 (13.3%) were admitted to a critical care unit.

Discussion: Midodrine exposures increased over time, particularly among individuals aged 20-59 years and 60 years and older, with a concomitant increase in retail midodrine dispensing. Although most exposures were managed at home, severe adverse effects have been reported, especially among patients with suspected suicidal ingestions compared to those with therapeutic errors. The National Poison Data System^® is limited by its passive surveillance design, and not all exposures are reported.

Conclusions: Better understanding of midodrine exposures and associated outcomes can inform poison center triage and medical management. Improved surveillance and clinician awareness may reduce morbidity and mortality associated with midodrine toxicity.