Naloxone has a short duration of action (shorter than that of some opiates), and its duration of action is influenced by the pharmacology and toxicity of the overdose drug.15 The serum half-life in adults ranges from 30 to 81 mins, and clinical impact varies from minutes to an hour.15 Thus, even if a patient initially improves after administration, close observation is mandatory due to the frequent need for repeat naloxone dosing.
Adverse effects. Naloxone is considered safe, with relatively few adverse effects and doesn’t have any effects on someone who isn’t experiencing an opioid overdose or currently on opioids.15 The only downside is that naloxone administration to an opioid-dependent person often precipitates an acute withdrawal event, characterized by global pain, agitation, generalized distress, and gastrointestinal complaints, including vomiting and diarrhea. Although withdrawal is not life-threatening, it can cause great discomfort.
Getting a handle on naloxone dosing
The starting dose of naloxone used to be 0.04 mg, but this was later increased to 0.4 mg. The advent and high overdose lethality of more potent drugs like fentanyl and carfentanil has made low-dose naloxone less effective.12
Currently, 1 mg is often the initial recommendation, but doses of 2 to 4 mg are not uncommon, and multiple administrations or continuous IV administration are frequently needed to reverse severe toxicities, such as those involving fentanyl or longer-action opioids like methadone. Anyone exhibiting difficulty breathing mandates a starting naloxone dose of at least 1 to 2 mg.12,16 In addition to breathing, additional doses are indicated clinically by medical parameters such as vital signs, ocular pupil diameter, and/or alertness.6
Intranasal administration often utilizes up to 4 mg of naloxone in one nostril, followed by a titrated additional administration in the other nostril. In life-threatening circumstances, especially those in which a patient is exhibiting respiratory depression, a much larger quantity of naloxone—up to 10 mg—may be administered by trained medical personnel.12,16 In the end, all dosing varies and must be individualized to the patient’s signs and symptoms. Those who have overdosed require prolonged monitoring to treat potential complications.
Emergency assistance and transport. Because of the dangers that can result from opioid toxicities, any hint or evidence of physiologic compromise merits a 911 call for emergency medical assistance and transport to a hospital emergency department (ED). Hospitalization is at the physician’s discretion.