Accidental tiotropium overdose in a child: a case report

Objective: Tiotropium is a long-acting anticholinergic agent increasingly used via inhalation in the management of chronic obstructive pulmonary disease. Toxicity following oral ingestion of capsules intended for inhalation has not previously been reported, and has been considered unlikely unless large amounts have been ingested because of low oral bioavailability.¹ We describe a case of an accidental oral overdose of tiotropium in a paediatric patient resulting in an anticholinergic toxidrome. Case report: The National Poisons Information Service (NPIS) was contacted about a 2 year old female patient following accidental ingestion of 8 capsules (144 micrograms) of tiotropium (Spiriva®) who had presented with features of anticholinergic toxicity including dry mouth, dilated pupils, tachycardia (133 beats/minute) and localised flushing of the cheek. Conservative management was advised with observation for at least 6 hours post-exposure or until asymptomatic. The patient was discharged after observation for six hours by which time all symptoms, except flushing, had resolved. The flushing was clinically deemed to be unrelated to the ingestion. A literature search did not reveal any reports of oral toxicity with tiotropium in any age group. Anticholinergic toxicity due to accidental inhalation has been reported with a dose of 90 micrograms in a 74 year old, who developed tachycardia, urinary retention and dry mouth.² Over 5 years the UK National poisons Information Service has received enquiries about 21 episodes of accidental oral ingestion in paediatric patients (0–10 years). The majority were asymptomatic, in spite of ingesting high doses. A 3 year old ingested 216 micrograms with no symptoms reported at 6 hours. A one year old referred to hospital was asymptomatic after ingesting 180 micrograms. A 4 year old patient was reported to have a dry mouth after ingesting 18 micrograms; this was treated conservatively at home. Conclusion: Anticholinergic features can develop after ingestion of tiotropium capsules by children, but this appears uncommon. References: 1. Product Information (SPC) Spiriva 18 microgram inhalation powder, hard capsule. Boehringer Ingelheim Limited. http://www.medicines.org.uk/EMC/medicine/10039/SPC/Spiriva+18+microgram+inhalation+powder%2c+hard+capsule/#OVERDOSE (accessed on 9 November 2010). 2. Gregory MD, Mersfelder TL, Jamieson T. Accidental overdose of tiotropium in a patient with atrial fibrillation. Ann Pharmacother 2010; 44:391–3.