Naloxone

Naloxone is an emergency opioid-reversal medicine available in several products, forms, and routes. Here is the full range of supported uses:

• Emergency treatment of known or suspected opioid overdose (slowed or stopped breathing, unresponsiveness) — supported by all nasal spray products (Narcan, Kloxxado, Rextovy, Rezenopy, Naloxone HCl Nasal Spray) and by Zimhi injection, for adults and pediatric patients
• Complete or partial reversal of opioid depression — including breathing depression caused by natural opioids, synthetic opioids, methadone, propoxyphene, and certain mixed opioid agents (nalbuphine, pentazocine, butorphanol, cyclazocine) — supported by Naloxone Hydrochloride injection (intramuscular, intravenous, or subcutaneous)
• Diagnosis of suspected or known acute opioid overdose — supported by Naloxone Hydrochloride injection
• Supporting treatment to help raise blood pressure in septic shock — Naloxone Hydrochloride injection may be useful as an add-on therapy in this setting
• Emergency treatment of patients 12 years and older when exposure to high-potency opioids (such as fentanyl analogues) used as a chemical weapon is suspected — specific to the Naloxone Hydrochloride Auto-Injector, for use by military personnel and chemical incident responders
• Temporary prevention of breathing or nervous system depression in military personnel and chemical incident responders entering areas contaminated with high-potency opioids — specific to the Naloxone Hydrochloride Auto-Injector

Naloxone is an opioid antagonist — meaning it directly competes with opioids for the same receptor sites in the brain and body. When it wins that competition and binds to the receptors, it rapidly knocks the opioid off and reverses its dangerous effects: breathing normalizes, sedation lifts, and blood pressure stabilizes. It can also reverse unusual mental effects (such as hallucinations or agitation) caused by certain mixed opioid agents like pentazocine.

Naloxone is an emergency-only medicine, not taken on a schedule. Nasal spray products are given as a single spray into one nostril; if the person doesn't respond within 2 to 3 minutes, an additional spray with a new device can be given into the other nostril — repeating every 2 to 3 minutes as needed until paramedics arrive. Injectable forms may be given into the muscle, under the skin, or into a vein depending on the specific product and clinical setting; intravenous administration works fastest and is preferred in emergencies when possible. There is no food restriction, as naloxone is given in emergencies and not taken orally. Always follow the prescriber's instructions and the product's specific Instructions for Use.

When naloxone reverses an opioid overdose, some side effects are expected — many are signs that the opioid is being rapidly cleared from the receptors:

• Shaking or trembling
• Sweating
• Nausea or vomiting
• Agitation or irritability upon waking
• Headache
• Dizziness
• Nasal discomfort or congestion (with nasal spray forms)
• Abdominal pain

More serious reactions — including dangerous changes in heart rhythm, very high or very low blood pressure, fluid in the lungs, or seizures (especially in newborns) — require immediate emergency care. These are most likely to occur in people with existing heart problems or in those who are heavily opioid-dependent.

• Opioid effects can return: Naloxone wears off faster than many opioids. Breathing problems can come back — always call 911 immediately after giving a dose and watch the person continuously.
• Severe opioid withdrawal: In people dependent on opioids, naloxone causes sudden, intense withdrawal — rapid heartbeat, high blood pressure, vomiting, severe body aches, and more. In newborns, this can include seizures and is potentially life-threatening.
• Cardiovascular risks after reversal: Abrupt reversal of opioids, especially after surgery, can trigger dangerous heart rhythms, very high blood pressure, fluid buildup in the lungs (pulmonary edema), and cardiac arrest — particularly in people with pre-existing heart disease.
• Incomplete reversal with some opioids: Buprenorphine and similar partial or mixed opioid agents may not be fully reversed by a single dose — larger or repeated doses may be needed.
• Needlestick risk (Zimhi): After use, the needle on Zimhi is exposed until the safety guard deploys. An accidental needlestick carries risk of bloodborne illness — seek immediate medical evaluation if this occurs.

The most important interactions with naloxone relate to opioids and opioid-like medicines:

• All opioids (natural, synthetic, and mixed): Naloxone directly reverses their effects — this is the intended action in overdose, but it will also remove pain relief in patients using opioids therapeutically
• Buprenorphine and pentazocine (partial or mixed opioid agents): These may be harder to reverse because of how tightly they bind to opioid receptors — more or larger doses of naloxone may be needed
• Medications with cardiovascular effects: When used with drugs that also affect heart rate or blood pressure, the abrupt opioid reversal caused by naloxone can increase the risk of serious heart-related events

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• Do not use naloxone if you have a known allergy to naloxone hydrochloride or any ingredient in the specific product
• If you are physically dependent on opioids, naloxone will trigger sudden, severe withdrawal — tell emergency responders so they can monitor and manage this
• Pregnancy: naloxone crosses the placenta and can cause withdrawal in the fetus; the fetus must be evaluated for signs of distress after use and both mother and baby need close monitoring
• Breastfeeding: naloxone is unlikely to reach the breastfed baby in meaningful amounts, but discuss with your provider
• Children: Kloxxado, Rextovy, and Rezenopy nasal sprays are established for pediatric use of all ages; however, absorption through the nose in young children may be unpredictable, and the child should be monitored for at least 24 hours after use
• Newborns exposed to maternal opioids: abrupt reversal can cause life-threatening seizures; a weight-adjusted injectable form that can be carefully titrated may be preferred
• Older adults: use cautiously, as decreased liver, kidney, or heart function is more common with age
• Pre-existing heart disease: patients with cardiac conditions need close monitoring in a healthcare setting after naloxone is given, due to risk of serious cardiovascular effects from rapid opioid reversal

When given intravenously, naloxone's effects are generally apparent within two minutes. The intravenous route works faster than intramuscular or subcutaneous injection. How long naloxone's effects last depends on the dose used and the route of administration — this is why repeated doses are often needed, since many opioids outlast it.

Naloxone is absorbed quickly after nasal administration, with peak blood levels typically reached within about 10 to 15 minutes for nasal spray forms. After parenteral (injected) administration, it is distributed widely throughout the body and readily crosses the placenta. It binds weakly to plasma proteins, primarily albumin. Naloxone has a relatively short half-life (the time it takes the body to clear half the drug) — roughly 1 to 2.5 hours depending on the route and product — which is why opioid effects can return after a single dose and repeat dosing is often necessary. It is not known whether naloxone passes into human breast milk.

and Shipping Store at controlled room temperature 15°C - 25°C (59°F - 77°F); excursions permitted between 4°C and 40°C (39°F and 104°F). Do not freeze. Protect from heat.