ZURNAI (AUTOINJECTOR)
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ZURNAI (AUTOINJECTOR) (ZURNAI (AUTOINJECTOR)).
Hyaluronidase degradation of interstitial hyaluronan, increasing tissue permeability to facilitate fluid dispersion and drug absorption.
| Metabolism | Primarily hepatic via proteolysis; renally excreted as small peptides. |
| Excretion | Primarily renal excretion as unchanged drug or acetylated metabolite (about 70-80% of the dose). A small fraction undergoes biliary/fecal excretion (<10%). |
| Half-life | Terminal elimination half-life is approximately 2.5 hours in adults. In renal impairment, half-life may extend up to 6 hours, necessitating dosing adjustments. |
| Protein binding | Approximately 20-30% bound to plasma proteins (mainly albumin). |
| Volume of Distribution | Volume of distribution (Vd) is approximately 2-4 L/kg, suggesting extensive tissue distribution beyond plasma volume. |
| Bioavailability | Subcutaneous injection: Approximately 100% (complete bioavailability). |
| Onset of Action | Subcutaneous: Muscarinic effects (e.g., sweating) appear within 15-30 minutes; clinical therapeutic effect (e.g., cognitive improvement) may require 4-6 weeks of chronic dosing. |
| Duration of Action | Subcutaneous: Duration of peripheral muscarinic effects (e.g., increased secretions) is 3-6 hours. Cognitive benefits from chronic therapy persist as long as dosing continues. |
Epinephrine 0.3 mg intramuscularly (into anterolateral thigh) every 5-15 minutes as needed for anaphylaxis.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for renal impairment; epinephrine is rapidly metabolized and not renally cleared. |
| Liver impairment | No specific dose adjustment for hepatic impairment; use with caution in severe hepatic disease due to potential increased sensitivity. |
| Pediatric use | Children 15-30 kg: 0.15 mg intramuscularly (anterolateral thigh) every 5-15 minutes as needed; children >30 kg: 0.3 mg intramuscularly every 5-15 minutes as needed. For infants <15 kg, use epinephrine 1 mg/mL solution (0.01 mg/kg) via syringe. |
| Geriatric use | Use standard adult dose (0.3 mg intramuscularly) with caution due to increased risk of adverse cardiovascular effects; monitor for hypertension, tachycardia, and myocardial ischemia. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ZURNAI (AUTOINJECTOR) (ZURNAI (AUTOINJECTOR)).
| Breastfeeding | Naloxone is excreted into human milk in low amounts; the milk-to-plasma ratio is estimated to be approximately 0.13 to 0.8. Due to poor oral bioavailability, it is unlikely to cause systemic effects in the breastfed infant. However, caution is advised, especially if the mother is opioid-dependent, as use of naloxone may precipitate withdrawal in the mother and potentially in the infant. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for naloxone. |
| Teratogenic Risk | FDA Pregnancy Category C: Zurnai (naloxone autoinjector) has not been studied in pregnant women. In animal reproduction studies, naloxone administered during organogenesis at doses up to 100 times the human dose showed no evidence of teratogenicity or fetotoxicity. However, naloxone crosses the placenta and may precipitate opioid withdrawal in the fetus, potentially leading to adverse effects such as preterm labor, fetal distress, or stillbirth. Use during pregnancy only if the potential benefit justifies the risk to the fetus. |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
Hypersensitivity to hyaluronidase; injection into infected or cancerous sites; for enhancing absorption of dopamine or alpha-adrenergic agonists.
| Precautions | Do not use in infected or inflamed injection sites; risk of hypersensitivity reactions; avoid for intraocular injection or venom dispersal. |
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| Fetal Monitoring | Monitor the pregnant patient for signs of opioid withdrawal, including fetal heart rate abnormalities, preterm labor, and changes in fetal movement. Continuous fetal monitoring is recommended after administration of naloxone during pregnancy, especially in opioid-dependent patients. Also monitor maternal vital signs and level of consciousness. |
| Fertility Effects | There are no controlled studies on the effects of naloxone on human fertility. In animal studies, naloxone at high doses did not impair fertility in rats. However, naloxone can interfere with endogenous opioid systems, which may affect reproductive hormone regulation. Opioid withdrawal induced by naloxone may temporarily disrupt menstrual cyclicity or spermatogenesis, but long-term effects on fertility are not well characterized. |