| Structure/Class |
- Pure competitive antagonist at the opioid receptor.
|
| Pharmacodynamics |
- High affinity for the µ receptor. Limited affinity for κ and δ receptors.
- When given alone (i.e. no agonist present) the drug is inert.
- When given with an agonist, it reverses the opioid effect completely in 1-3 minutes.
- Respirations, level of consciousness, pupil size and awareness of pain are normalized.
- No tolerance nor withdrawal will develop.
|
| Absorption/administration |
- IV. IM may be used to prolonged duration of action.
|
| Distribution |
- Localised in highly perfused tissues.
- Short T ½ – 60 to 90 minutes.
|
| Metabolism |
- Hepatic
|
| Excretion |
- Renal
|
| Indications |
- Reverses opioid toxicity
- Diagnostic tool
|
| Contraindications |
|
| Special precautions |
- Short T ½ – therefore, patient requires close monitoring and may need repeated doses.
- Can precipitate withdrawal symptoms.
- May precipitate APO due to sympathetic surge.
|
| Interactions |
|
| Adverse events |
|
| Dosing/administration |
- 0.1 to 0.4 mg, repeat as necessary. Also may be given IM.
|
| Toxicology |
|
| Withdrawal syndrome |
|
| Special notes |
|
