Guanfacine exposure in paediatric and adolescent patients: A multicentre retrospective review

To describe the frequency, severity, management and complications of guanfacine exposures in paediatric and adolescent patients referred to a state Poisons Information Centre or presenting to two EDs.

A multicentre, retrospective review of guanfacine exposures from July 2017 to October 2023 in patients aged ≤19 years that were discussed with the Victorian Poisons Information Centre or presented to the Royal Children's Hospital or Austin Health EDs, Melbourne. Demographic, clinical, management and outcome data were examined.

There were 275 guanfacine exposures reported to the Poisons Information Centre, with a 16-fold increase in exposures over the study period. Of these, 173 (63%) were unintentional therapeutic errors, the majority (103) involving accidental double-dosing. Twenty-four cases presented to either of the study EDs and 38 cases from other hospitals were discussed with a clinical toxicologist. Of these 62 cases with a medical assessment, 32 reported lone guanfacine exposure. Hypotension, bradycardia and drowsiness were present in 9/32, 17/32 and 13/32 cases, respectively. Five (16%) patients received i.v. fluids. No patients required intubation, inotropic or vasopressor support. One patient who was co-exposed to marijuana required atropine. Prolonged orthostatic hypotension was observed in three of 32 cases, lasting a median of 36 h (range 24-42 h).

Paediatric guanfacine exposures increased significantly over the study period. Isolated guanfacine ingestions were well tolerated, seldom requiring specific intervention. Clinicians need to be cognisant of the risk of prolonged orthostatic hypotension, and this must be excluded prior to discharge.