Abstract:
Fipronil, a broad spectrum N-phenylpyrazole insecticide
that inhibits GABAA-gated chloride channels, has been in use since the mid1990s. A high affinity for insect compared to mammalian GABA receptors results
in lower animal toxicity than other insecticides blocking this channel. To date,
only two accidental cases of fipronil poisoning in humans have been published.
Case series-We report seven patients with fipronil self-poisoning seen
prospectively in Sri Lanka together with pharmacokinetics for four patients. Nonsustained generalized tonic-clonic seizures were seen in two patients (peak
measured plasma fipronil concentrations 1600 and 3744 ìg/L); both were managed
with diazepam without complications. A patient with a peak measured plasma
concentration of 1040 ìg/L was asymptomatic throughout his stay. Plasma
concentration was still high at discharge 3-4 days post-ingestion when the patients
were well. Retrospective review of >1000 pesticide poisoning deaths since 1995
found only one death from fipronil-based products. In contrast to the good
outcome of the above cases, this patient required intubation and ventilation and
had continuous fits despite therapy with barbiturates and benzodiazepines.
Conclusions-Our experience with prospectively observed patients suggests that
fipronil poisoning is characterized by vomiting, agitation, and seizures, and
normally has a favorable outcome. Management should concentrate on supportive
care and early treatment of seizures. However, further experience is needed to
determine whether increased susceptibility to fipronil or larger doses can produce
status epilepticus.
