Naloxone HCL

(naloxone hydrochloride)


P/M Naloxone HCL, Narcan


  • Injectable: 0.02 mg/mL, 0.4 mg/mL & 1 mg/mL *Note: 0.02 mg/mL is preservative-free.


Naloxone is an opiate antagonist. It is structurally related to oxymorphone. Considered a pure antagonist, naloxone has no analgesic activity. Naloxone is believed to act competitively by binding to the mu, kappa, and sigma opioid receptor sites. It reverses the effects that are associated with opiate administration such as respiratory and CNS depression.

Naloxone is minimally absorbed when given orally due to it being rapidly destroyed in the GI tract. It is therefore given IV, IP, or IM for a more rapid onset of action. The duration of action, of naloxone, can be anywhere from 45 minutes to 3 hours.

Naloxone is rapidly distributed throughout the body with higher levels found in brain, kidneys, spleen, skeletal muscle, lung and heart. It readily crosses the placenta, however, is considered to be non-teratogenic. It is metabolized in the liver via glucuronidative conjugation with metabolites excreted in urine.


Used for reversal of opioid effects (involving respiratory depression, & sedation) in rats.

Drug Interactions or Contraindications

  • Naloxone should be used cautiously where cardiac conditions may be present.

Adverse Reactions

Relatively free of adverse effects at normal doses.

CNS: tremors, seizures

CV: tachycardia, hypertension

GI: nausea, inappetance

Dosage Recommendations

Administered, as necessary, since the duration of action of some opioids may exceed that of Narcan.

0.01 mg/kg to 0.1 mg/kg, SQ, IV or IP, as needed. 42


0.01 mg/kg to 0.1 mg/kg, SQ, IP. 26, 26, 27, 34, 41, 44


0.01 mg/kg to 0.1 mg/kg, IP or IV, as needed. 2


  • Naloxone is not effective against respiratory depression due to non-opioid drugs.
  • *Note: an incomplete response may occur when naloxone is given to reverse respiratory depression of partial agonists or mixed agonist/antagonists, such as buprenorphine and pentazocine. Adjust dosage of naloxone, monitor closely, and provide respiratory support as needed.
  • Naloxone is relatively stable having a shelf life between 18 months and two years. Injectable naloxone should be stored at room temperature between 59oF. and 86oF., and should be kept out of direct sunlight.


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