OBJECTIVE: Benzodiazepine (BZD) overdose (OD) continues to cause significant 
morbidity and mortality in the UK. Flumazenil is an effective antidote but there 
is a risk of seizures, particularly in those who have co-ingested tricyclic 
antidepressants. A study was undertaken to examine the frequency of use, safety 
and efficacy of flumazenil in the management of BZD OD in the UK.
METHODS: A 2-year retrospective cohort study was performed of all enquiries to 
the UK National Poisons Information Service involving BZD OD.
RESULTS: Flumazenil was administered to 80 patients in 4504 BZD-related 
enquiries, 68 of whom did not have ventilatory failure or had recognised 
contraindications to flumazenil. Factors associated with flumazenil use were 
increased age, severe poisoning and ventilatory failure. Co-ingestion of 
tricyclic antidepressants and chronic obstructive pulmonary disease did not 
influence flumazenil administration. Seizure frequency in patients not treated 
with flumazenil was 0.3%. The frequency of prior seizure in flumazenil-treated 
patients was 30 times higher (8.8%). Seven patients who had seizures prior to 
flumazenil therapy had no recurrence of their seizures. Ventilation or 
consciousness improved in 70% of flumazenil-treated patients. Flumazenil 
administration was followed by one instance each of agitation and brief seizure.
CONCLUSIONS: Flumazenil is used infrequently in the management of BZD OD in the 
UK. It was effective and associated with a low incidence of seizure. These 
results compare favourably with the results of published randomised controlled 
trials and cohort studies, although previous studies have not reported the use 
of flumazenil in such a high-risk population. This study should inform the 
continuing review of national guidance on flumazenil therapy.