Rising prescription stimulant poisoning in Australia: a retrospective case series

Abstract

With rising therapeutic use worldwide, prescription stimulants are increasingly implicated in poisonings. Most of the limited research on stimulant poisoning focuses on illicit amphetamines. We aimed to investigate the clinical effects of intentional prescription stimulant poisoning. This is a retrospective review of hospitalised patients referred to a Poisons Information Centre and a toxicology unit following intentional exposures to prescription stimulants (dexamfetamine, lisdexamfetamine and methylphenidate) from 1 January 2018 through 31 December 2021. Patients were identified from both units’ databases and data extracted from medical records. To facilitate comparison a dexamfetamine-equivalent dose was calculated. There were 186 intentional exposures in 178 patients (median age 17 years, males 54%) over the study period, consisting of 44 (24%) dexamfetamine, 50 (27%) lisdexamfetamine and 92 (49%) methylphenidate exposures. Stimulant exposures rose annually from 34 presentations in 2018 to 61 in 2021. Deliberate self-poisoning accounted for 139 (75%) presentations and the remaining 47 (25%) were recreational. Co-ingestions were taken in 101 (54%) presentations, leaving 85 (46%) single-agent exposures with a median dexamfetamine-equivalent dose ingested of 135 mg (range 15-4500 mg). Of the single-agent exposures tachycardia (69%), hypertension (47%) and agitation (58%) were the commonest clinical features. Most patients (58%) had mild-moderate symptoms, managed solely with supportive cares or oral sedation. Twenty-three (27%) patients had severe agitation receiving parenteral sedation. Rhabdomyolysis occurred in 3 single-agent exposures (4%) and 8 (9%) had an acute kidney injury. Severe cardiovascular toxicity was rare, with one patient developing hypertensive crisis and another having a supraventricular tachycardia. The median length of stay for single-agent exposures was 11 h (IQR 5-19 h). Prescription stimulant poisoning appears to be rising and commonly results in tachycardia, hypertension, and agitation. Severe cardiovascular toxicity was rare.