Naloxone
Also known as: Narcan
- **Purpose**: Naloxone is an emergency medication used to reverse the effects of opioid pain medications or treat opioid overdoses. - **What to Expect**: Your pet may wake up quickly from sedation. Because naloxone reverses the pain medication, your pet might experience a sudden return of pain. - **Monitoring**: The effects of naloxone can wear off before the opioid does. Watch your pet closely for a return of extreme sleepiness, slow breathing, or unresponsiveness. - **Administration**: Usually given by a veterinary professional, but in some cases (like for newborn puppies or kittens), you may be instructed to place a drop under the tongue.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- Opioid reversal
- Neonatal opioid reversal (following caesarian sections)
- Adjunctive treatment of hyperthermia
- Opioid overdose / reversal
- Opioid overdose / reversal
- Prolonged opioid antagonism
- Opioid reversal
- Limit increases in locomotor activity secondary to narcotic agonists
- Treatment of opioid gastrointestinal tract dysfunction
- Opioid reversal in rodents
- Opioid reversal in rabbits
- Opioid reversal in hamsters, gerbils, mice, rats, guinea pigs, chinchillas
- Opioid reversal
How it is given
Possible side effects
- Reversal of analgesia (return of pain)
- Acute withdrawal syndrome in opioid-dependent patients
- CNS excitement (especially if used in meperidine overdose)
- Seizures (at very high doses, likely secondary to GABA antagonism)
- Acute severe discomfort or pain (due to sudden loss of analgesia)
- Antanalgesic effects in opioid-naïve subjects
- Transient elevation of unconsciousness (at low doses)
Cautions & contraindications
- Hypersensitivity to naloxone
- Indiscriminate use in animals that have undergone major surgery or trauma (due to severe pain from analgesia reversal)
- > **Important Warning:** The duration of action of naloxone (45-90 minutes) is often shorter than the opioid it is reversing. Patients may slip back into respiratory depression and require re-dosing or continuous ventilatory support. - Use with caution in animals with preexisting cardiac abnormalities. - Use cautiously in opioid-dependent animals or those that have received exceedingly large doses of narcotics, as it may precipitate an acute withdrawal syndrome. - **Meperidine Toxicity:** Naloxone is reportedly not effective for reversing meperidine-induced seizures and may elicit CNS excitement if normeperidine excitotoxicity is present. Avoid unless severe respiratory depression is present without ventilatory support. - **Buprenorphine:** Naloxone is not a good reversal agent for buprenorphine due to buprenorphine's high receptor affinity; massive doses (100X usual) may be required.
Drug interactions
- Opioid partial-agonists (butorphanol, pentazocine, nalbuphine): Naloxone may antagonize the effects of these agents (respiratory depression, analgesia). It should not be relied upon to treat respiratory depression caused by buprenorphine.
- Clonidine: Naloxone may reduce the hypotensive and bradycardic effects of clonidine; potentially useful for clonidine overdoses.
- Yohimbine: Naloxone may increase the CNS effects of yohimbine (anxiety, tremors, nausea, palpitations) and increase plasma cortisol levels.
- Opioid Agonists (e.g., Morphine, Methadone, Fentanyl): Naloxone reverses the analgesic, sedative, and respiratory depressant effects of opioid agonists.
- Buprenorphine: Buprenorphine binds tightly to opioid receptors; naloxone may not fully reverse its effects or may require much higher doses.
Frequently asked questions
What is Naloxone used for in pets?
- **Purpose**: Naloxone is an emergency medication used to reverse the effects of opioid pain medications or treat opioid overdoses. - **What to Expect**: Your pet may wake up quickly from sedation. Because naloxone reverses the pain medication, your pet might experience a sudden return of pain. - **Monitoring**: The effects of naloxone can wear off before the opioid does. Watch your pet closely for a return of extreme sleepiness, slow breathing, or unresponsiveness. - **Administration**: Usually given by a veterinary professional, but in some cases (like for newborn puppies or kittens), you may be instructed to place a drop under the tongue.
Is Naloxone safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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