Brimonidine Eye Drops at the Children Reach: A Possible Foe

Brimonidine, a selective alpha-2 adrenergic agonist, used for treatment of open-angle glaucoma, has been shown to cause neurological side effects such as unresponsiveness, lethargy, hypoventilation, and stupor, mimicking opioid toxicity. We report one case of transient encephalopathy in a toddler, in whom brimonidine accidental toxicity was sus-pected and then confirmed by a toxicology study. The 8-month-old healthy girl child was taken to the pediatric ER since she was drowsy and hypotonic, with miosis. Brain CT scan and toxicological work-up on blood and urine were negative. Starting from hour +4, the child progressively improved, and by hour +6, she recovered to a normal state of consciousness. A survey of available drugs at the child’s reach showed the presence of brimonidine. Thus, ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was applied to quantify brimonidine in urine and plasma samples, showing 8.40 ng/mL level and 0.79 ng/mL, respectively. To our knowledge, this is the first report for determining brimonidine levels in urine and plasma by UPLC-MS/MS. Insufficient knowledge of the family members about the potential hazards of an apparently innocuous, topical medication such as eye drops may put children at a greater risk of poisoning. Necessary warnings should be better given to parents when prescribing this medication.