To the Editor,
We have read carefully the interesting article on brimonidine
poisoning published by Becker et al. [1] in the last issue of
“Pediatrics”. Our team has recently reported in “Pediatric Emergency Care”
a case of accidental poisoning by brimonidine in a 16-week old infant
presenting with intracranial hypertension syndrome and which became
subsequently self-limited after intensive monitorization.
In relation to this topic, we would like to expound our experience
and contribute with some interesting comments.
We agree with the above mentioned authors in that the use of
brimonidine in children is common when there are no other therapeutic
options, despite the fact that it is not authorized either in the USA or
in Europe.
As regards the toxicity and selectivity of brimonidine, in spite of
its supposedly improved pharmacokinetic - higher water solubility and
diminished hematoencephalic barrier permeability- , we agree with the
authors in the risk of ocular administration and the increased
conjunctival permeability due to the inability to accurately control the
final dose.
We would like to highlight the necessity to intubate patients, as
reported. The therapeutic dose is so high and/or the weight of the child
so low, to produce toxicity that we must be aware of these circumstances
irrespective of their low incidence. Generally, the administration of
topic brimonidine does not provoke serious reactions, which are normally
due to accidental oral ingestion. On the other hand, there is a wide
variety of symptoms. In the case we describe, the clinical presentation in
the form of combination of hypertension, bradycardia and superficial
breathing, typical signs of intracranial hypertension, is rare. Obviously,
the diagnosis of brimonidine poisoning in children is difficult and it is
not well established.
Considering the use of naloxone as an antidote, despite the existence
of several reports on its efficacy, we have never used this drug in our
milieu. The clinical symptoms are usually mild and/or temporary. Intensive
monitorization, as was the case of our patient, is usually enough.
Moreover, naxolone therapy has some side effects [1- 3]. The literature on
the subject [4-6] shows contradictory experiences. Whenever intubation or
severe hemodynamic instability occurs, naxolone therapy could be
justified, but in most instances, this practice can be counterproductive.
As a norm, the age of the cases reported is < 5 years, but cases
of patients under this age, as the one we describe, are very uncommon. In
patients of this age group, several diseases can provoke symptoms similar
to those of brimonidine poisoning. Consequently, we should perform a great
variety of tests including glucose, sodium, potassium and the rest of
conventional ions as well as capillary gasometry, cranial and abdominal
echography, blood and urine cultures and thoracic X-rays. Also, the
complex differential diagnosis of this condition together with the scarce
information parents can provide in these situations, should prompt us to
suspect of poisoning in patients treated with brimonidine, but we must
also consider the rest of possibilities.
Finally, irrespective of the measures necessary to control
brimonidine poisoning symptoms, we must insist on the fact that this drug
is contraindicated in pediatric patients.
REFERENCES
1. Brimonidine tartrate poisoning in children: frequency, trends, and
use of naloxone as an antidote. Becker ML, Huntington N, Woolf AD.
Pediatrics. 2009 Feb;123(2):e305-11
2. Pediatric systemic poisoning resulting from brimonidine ophthalmic
drops. Fernandez MA, Rojas MD. Pediatr Emerg Care. 2009 Jan;25(1):59
3. Brimonidine intoxication in paediatrics. A presentation as intracranial
hypertension syndrome] Fernández Fernández MA, Morillo Rojas MD, Ribó
Golovart MA, Ribó Marco A. An Pediatr (Barc). 2008 Aug;69(2):159-61
4. Ocular hypertension in children treated with brimonidine 0.2%. A
clinical study] Montero-de-Espinosa I, Márquez-de-Aracena R, Morales C.
Arch Soc Esp Oftalmol. 2006 Mar;81(3):155-9.ç
5. Drug therapy of opioid withdrawal] Cortese S, Risso M. Vertex. 2008 Jan
-Feb;19(77):522-6.
6. Naloxone and cardiogenic shock]. Unzueta Merino MC, Bonnin O, Cabrera
Ruiz JC, Villar Landeira JM. Rev Esp Anestesiol Reanim. 1987 Nov-
Dec;34(6):446-9.
Conflict of Interest:
None declared
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