Unintentional overdose of an opioid can usually be managed expectantly; however, if partial reversal is necessary, very low-dose naloxone (formerly Narcan) can be quickly administered by giving - to -mg (or mcg per kg) intravenous or intramuscular boluses every three to five minutes, titrated to respiratory rate or mental status (mix one mg per mL ampule of naloxone with saline to make 10 mL, which equals mg per mL). 27 Continued close monitoring is necessary because duration of opioid effect may outlast naloxone.
The intravenous route is not FDA approved and is generally not recommended except when no other alternatives are available. Intravenous administration appears to be associated with a higher risk of QT prolongation and torsade de pointes (TdP) than other forms of administration. The manufacturer recommends ECG monitoring for QT prolongation and arrhythmias if IV administration is required. A dose in the range of 1 to 5 mg IV has been suggested, with the dose being repeated at 30 to 60 minute intervals, if needed. A maximum IV dose has not been established. The lowest effective dose should be used in conjunction with conversion to oral therapy as soon as possible.