Use of antidotes in cases of poisoning from drugs of abuse treated in Spanish emergency departments

Abstract

Objective: To analyze the use of antidotes for street-drug poisonings treated in Spanish emergency departments (EDs), the appropriateness of antidote use in these cases, and adverse events related to antidotes.

Methods: Eleven EDs belonging to the Spanish network for the study of drug poisonings treated in Spanish hospitals (REDUrHE) registered data for patients treated over a period of 24 months. Poisonings exclusively involving alcohol were excluded. Sociodemographic and clinical data (including episode severity and clinical management) were recorded. Cases were grouped for comparisons according whether or not antidotes were administered during the episode, were used in the hospital ED or out-of-hospital, and were used appropriately according to the American Heart Association and CALITOX-2006 recommendations.

Results: A total of 4481 patients were included; 351 (7.8%) were treated with an antidote (naloxone in 243 and flumazenil in 225). Both antidotes were used in 34.5% of these patients. Antidotes were most often used during outof-hospital care (in 79.3%). The use was inappropriate in 81.3% of the flumazenil-treated patients and in 70.7% of the naloxone-treated patients. Flumazenil was improperly given to patients with a score of more than 12 on the Glasgow Coma Scale in 49.7% of the patients treated with this antidote. Patients treated with an antidote had had convulsions or were under antiepileptic treatment (4.8% of the cases) or had used a proconvulsive substance (cocaine, 40.8%, or an amphetamine, 26.8%); and 25.9% required treatment with an anxiolytic or sedative. Serious neurological complications were reported after antidote administration in 5 patients (1.6%). The need for intubation and respiratory support in a critical care unit was significantly associated with inappropriate use of flumazenil (P .001); the need for sedation was associated with inappropriate use of naloxone (P = .02). Inappropriate use was not related to where the antidote was administered.

Conclusions: Antidotes, usually naloxone and flumazenil, were used to treat a high percentage of patients poisoned by drugs of abuse who are attended by Spanish EDs belonging to the REDUrHE. In a third of these cases, both antidotes were used. Use was associated with diminished consciousness. Use of the antidote, especially flumazenil, was inappropriate in most of the episodes.

Keywords: Adecuación terapéutica; Antidotes; Antídotos; Drogas de abuso; Emergency department; Flumazenil; Flumazenilo; Illicit drugs; Inappropriate prescribing; Intoxicación; Naloxona; Poisoning; Urgencias.