Unintentional ingestion of brimonidine antiglaucoma drops: a case report and review of the literature

A previously healthy, 1-year 7-month-old boy was brought to the emergency department after having unintentionally ingested topical brimonidine antiglaucoma drops. He was pale and lethargic and had brief periods of apnea and bradycardia. Activated charcoal was administered, and supportive measures were initiated, achieving complete resolution of the symptoms 4 hours after admission. Brimonidine poisoning is very rare, and a high index of suspicion is necessary to identify its signs and symptoms in the pediatric emergency department. To our knowledge, only 1 case of brimonidine poisoning after oral ingestion of this topical drug has been previously reported in the literature.

Adrenoceptor agonist poisoning after accidental oral ingestion of brimonidine eye drops

OBJECTIVE

Brimonidine tartrate is a relatively selective alpha(2) adrenic agonist that lowers elevated intraocular pressure. A 2-yr-old boy presented with severe cardiorespiratory symptoms of systemic alpha(2) adrenergic intoxication after accidentally ingesting 2 mL of brimonidine ophthalmic solution (0.2%) orally. At 20 mins after ingestion, he became acutely pale and lethargic, with shallow infrequent respirations. The symptoms resolved completely within the next 10 hrs.

METHODS

The pharmacokinetics of brimonidine in plasma and urine were analyzed using gas chromatography and mass spectrometry.

RESULTS

Maximum plasma concentrations were 40 ng/mL 5 hrs after ingestion. The plasma elimination half-life value was 2.7 hrs. Elimination via urine was calculated as having a terminal half-life value of 3.2 hrs.

CONCLUSIONS

This case illustrates the ability of brimonidine to gain rapid access to the central nervous system. This first passage is followed by a redistribution phase with rising plasma concentrations. Children who accidentally ingest brimonidine orally should be admitted to a pediatric intensive care unit.

Clinical effects of brimonidine ophthalmic drops ingestion in 52 dogs

Brimonidine is an ophthalmic solution of 0.2% brimonidine tartrate used to lower intraocular pressure in human glaucoma patients. A retrospective study was conducted of brimonidine ophthalmic solution ingestion in 52 dogs reported to the ASPCA Animal Poison Control Center between January 1998 and December 2000. Eighty percent of the dogs were < 1-y of age. Approximate ingested dosages ranged from 0.18-5.55 mg/kg. Incidence of clinical signs were bradycardia (67%), depression (46%), ataxia (27%), hypotension (25%), pallor (23%), weakness (17%), change in mucous membrane color (17%), hypothermia (13%), vomiting or retching (13%.). Shock, weak pulses, and poor capillary refill time were also reported. Treatment involved early decontamination, supportive care, andyohimbine and atipamezole as specific alpha-2 antagonists that could be helpful in reversing the effects of brimonidine. Due to the possibility of severe cardiovascular effects developing, the ingestion of brimonidine ophthalmic solution in dogs should be considered dangerous.

Ophthalmic drops causing coma in an infant

A 1-month-old infant with Peters anomaly had recurrent episodes of unresponsiveness, hypotension, hypotonia, hypothermia, and bradycardia. An extensive medical evaluation determined these episodes to be caused by brimonidine, an anti-glaucoma agent. There is the potential for serious toxic effects from the systemic absorption of topically applied ophthalmic agents in children.

[Pathomorphologic course study in fattening pigs after olaquindox poisoning]

In an investigation over five months the adrenal toxic effect of the quinoxaline derivate olaquindox in pigs of different ages (10 and 16 weeks) after accidental feeding of a 15-fold overdosage of olaquindox is demonstrated. The substance induced clinical and hematological changes comparable with Addison's disease. A reduced gain of body weight was observed, predominant hematological findings were a hyperkalemia and a hyponatremia, which reversed to normal values after 17 weeks in the younger group and after 14 weeks in the older group. Whereas five weeks after the first intake of the feed, degenerative changes of the zona arcuata were most prominent, a destructive fibrosis and a reduction of the adrenal cortex were more marked 12 and 13 weeks later. Due to the loss of aldosterone the electrolyte imbalances led to degenerative changes in the skeletal muscles and in the myocardium. Pigs of younger age were more affected than elder ones. Subcapsular cells with basophilic nuclei resembling normal cells of the zona arcuata appear 18 to 22 weeks after the first overdosage of olaquindox and are suggestive in combination with normal electrolyte values of a regeneration of the zona arcuata.

[Clinical and hematological changes after olaquindox poisoning in fattening pigs]

A pig grower ration containing olaquindox at a concentration of 778 mg/kg was accidentally fed to 10 respectively 16 weeks old weaner pigs. The subsequent intoxication was characterized by poor growth and long-term disturbances of renal function and electrolyte metabolism. A deficiency of aldosterone, produced by a selective degeneration of the arcuate zone of the adrenal cortex, is probably the cause of the hyponatremia, hyperkalemia and hemoconcentration observed. Simultaneously plasma levels of urea and creatinine were elevated five- to eightfold. Due to hyperkalemia episodes with collapse, paralysis and severe electrocardiographic changes occurred several times. Two pigs died in the course of such attacks. Individuals, which transiently showed distinct clinical symptoms of intoxication, did not show any signs of disease 15 or 18 weeks later. Therefore it may be assumed, that the lesions of the adrenals, heart and skeletal muscle caused by olaquindox intoxication are reversible in some cases.

Accidental carbadox overdosage in pigs in an Irish weaner-producing herd

A weaner ration containing carbadox at concentrations of 331 to 363 mg/kg was accidentally fed to suckling and weaned pigs in an 84 sow herd. Discarded ration was fed to 36 sows. One hundred and sixty five weaner pigs died in a 10 week period with clinical signs including refusal to eat, ill thrift, the passing of hard pelleted faeces, posterior paresis and death in seven to nine days. The surviving weaners did not thrive and some males showed poor testicular development. Sows and suckling pigs that consumed the ration also failed to thrive as did the progeny of affected sows. The main pathological finding was obliteration of the zona glomerulosa of the adrenal cortex. Increased potassium and decreased sodium concentrations in serum were the most notable and consistent biochemical findings.