Effectiveness and safety of intravenous nalmefene for emergency department patients with suspected narcotic overdose: a pilot study.

STUDY OBJECTIVE: To evaluate the efficacy and safety of nalmefene, an investigational narcotic antagonist that has potential advantages over naloxone because of its four- to eight-hour half-life, in emergency department patients with possible narcotic overdose.

DESIGN: Multi-institutional, prospective, phase II, open-label study.

TYPE OF PARTICIPANTS: Complete data were available for 53 cases from two teaching hospitals. Men 18 years old or older who would otherwise receive naloxone were eligible (two women were enrolled inadvertently).

METHODS: Over four hours, one to ten boluses (median, one) of 0.5 or 1.0 mg nalmefene IV were given as often as every two minutes based on clinical need. Respirations, blood pressure, pulse, pupil size, and overall clinical response were monitored. Overall clinical response (1, no change; 2, partial response; 3, complete response), first assessed at two minutes, was analyzed by the Mann-Whitney U test.

RESULTS: Fifteen of 25 (0.5 mg) and nine of 28 (1.0 mg) cases were opiate positive. Twelve of 15 (0.5 mg) and six of nine (1.0 mg) opiate-positive cases had a rapid complete response. Coincident causes of depressed sensorium were identified in the remaining six opiate-positive cases. No difference in initial overall clinical response was seen between 0.5-mg and 1.0-mg opiate-positive cases (P = .59). No deterioration requiring repeat nalmefene occurred in opiate-positive cases, even if methadone (four), codeine (two), or pentazocine (one) was found. No serious adverse events were judged to be related to nalmefene.

CONCLUSION: Nalmefene is effective in the reversal of opiate overdose and appears to be safe in the management of patients with altered sensorium.