ZIMHI
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZIMHI (ZIMHI).
Opioid receptor antagonist; reverses opioid effects by competitively binding to mu-opioid receptors.
| Metabolism | Hepatic via glucuronidation; major metabolite naloxone-3-glucuronide. |
| Excretion | Renal: 30-35% unchanged; biliary/fecal: 50-60% as metabolites. |
| Half-life | Terminal half-life: 2.5-4 hours; clinical context: short duration requires repeat dosing for sustained opioid effects. |
| Protein binding | 30-40% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Vd: 3-5 L/kg; indicates extensive tissue distribution beyond plasma volume. |
| Bioavailability | Intravenous: 100%; Intramuscular: 60-70%. |
| Onset of Action | Intravenous: 2-5 minutes; Intramuscular: 10-15 minutes. |
| Duration of Action | Intravenous: 2-4 hours; Intramuscular: 3-6 hours; note: duration increases with dose. |
5 mg intramuscularly every 2-3 minutes as needed; maximum 3 doses.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for renal impairment. |
| Liver impairment | No specific Child-Pugh based adjustments; use with caution in severe hepatic impairment. |
| Pediatric use | 0.1 mg/kg intramuscularly every 2-3 minutes as needed; maximum single dose 5 mg. |
| Geriatric use | No specific adjustment; consider lower initial doses due to increased sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ZIMHI (ZIMHI).
| Breastfeeding | Naloxone is poorly excreted into breast milk; M/P ratio unknown. Due to low oral bioavailability, exposure to the infant is minimal. No adverse effects reported in breastfed infants. Use compatible with breastfeeding when indicated for maternal opioid overdose. |
| Teratogenic Risk | ZIMHI (naloxone) is not associated with increased risk of major birth defects. No teratogenic effects observed in animal studies. Limited human data, but naloxone is not expected to cause fetal harm due to its short half-life and lack of opioid agonist activity. Use in pregnancy may be necessary for maternal opioid overdose; benefit outweighs theoretical risk. |
■ FDA Black Box Warning
Risk of recurrent respiratory depression; patient must be monitored until fully recovered and opioid effects have subsided.
| Serious Effects |
["Hypersensitivity to naloxone hydrochloride or any component of the formulation"]
| Precautions | ["Risk of acute opioid withdrawal in physically dependent patients","Limited efficacy in buprenorphine or partial agonist overdose","May precipitate withdrawal in neonates"] |
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| Fetal Monitoring | Monitor for signs of opioid withdrawal in mother and fetus (fetal distress, preterm labor). Assess respiratory status and level of consciousness. Fetal monitoring (heart rate) may be considered in cases of maternal overdose. |
| Fertility Effects | No known effects on fertility. Naloxone does not alter reproductive hormone levels or gametogenesis. Studies in animals show no impairment of fertility at doses far exceeding human therapeutic exposure. |