To measure blood levels of morphine and additional drugs in patients suspected of intravenous (IV) heroin abuse and to evaluate the effects of antidote treatment.

Prehospital blood sampling in 52 patients.

Forty-five patients were blood-positive for heroin, eight of whom were hospitalized. Forty-one patients also had abused additional drugs: minor tranquilizers, ethanol, amphetamine, cocaine, and/or carbamazepine. Seven patients had taken either only methadone or ketobemidione: one was admitted. Treatment with increasing doses of naloxone indicated a necessity for hospitalization. Six of 14 patients treated with naloxone (1.8 mg were hospitalized. Seven patients had an extremely high blood level of morphine (0.2 mg/kg), that could be reverted with naloxone in moderate doses.

This study indicates that under prehospital conditions, it is difficult to identify a patient intoxicated only with intravenous heroin. Nearly all patients treated were cases of multiple drug/alcohol overdoses. Even the symptoms associated with extremely high blood levels of morphine could be reversed with naloxone in moderate doses.