Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
EVZIO vs KLOXXADO
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Naloxone is an opioid antagonist that competitively binds to mu-opioid receptors, reversing opioid-induced respiratory depression and analgesia.
KLOXXADO (flumazenil) is a benzodiazepine antagonist that competitively inhibits the activity at the benzodiazepine binding site on the GABA-A receptor, thereby reversing the effects of benzodiazepines.
Emergency treatment of known or suspected opioid overdose, as manifested by respiratory and/or central nervous system depression.
Reversal of conscious sedation induced by benzodiazepines,Management of benzodiazepine overdose,Off-label: reversal of benzodiazepine effects in hepatic encephalopathy
2 mg intramuscular (IM) or subcutaneous (SC) autoinjector into anterolateral thigh; repeat every 2-3 minutes as needed for opioid overdose.
5 mg intranasally as a single dose; may repeat once after 2-3 minutes if response inadequate.
The terminal elimination half-life of naloxone in adults is approximately 1-2 hours. In neonates, half-life may be prolonged to 3-4 hours. Clinical context: Short half-life necessitates repeated dosing or continuous infusion for sustained opioid reversal, especially with long-acting opioids.
Terminal elimination half-life is approximately 2 hours (range 1-4 hours); clinical context: short half-life supports rapid reversal of opioid effects but requires monitoring for renarcotization, especially with long-acting opioids.
Primarily hepatic glucuronidation, with N-allylnoroxymorphone as the major metabolite; CYP450 system not significantly involved.
Hepatic metabolism via CYP1A2 and CYP3A4; undergoes extensive first-pass metabolism; major metabolites are inactive or less active.
Naloxone undergoes extensive hepatic metabolism primarily via glucuronidation, with approximately 70% excreted in urine as naloxone-3-glucuronide. About 25% is excreted in feces via biliary elimination. Less than 1% is excreted unchanged in urine.
Hepatic metabolism primarily via CYP3A4 to inactive metabolites; renal excretion accounts for <1% of unchanged drug; fecal excretion accounts for approximately 50-60% of the dose as metabolites.
Approximately 30-40% bound to plasma proteins, mainly albumin.
Approximately 80% bound to plasma proteins, primarily albumin.
Volume of distribution is approximately 2-3 L/kg, indicating extensive distribution into tissues beyond plasma volume. Clinical meaning: High Vd suggests rapid distribution and short half-life.
Volume of distribution is approximately 2-4 L/kg; high Vd indicates extensive tissue distribution, which is consistent with rapid redistribution from brain to peripheral tissues, contributing to its short duration of action.
Intramuscular bioavailability is approximately 100% (assumed complete absorption). Oral bioavailability is <2% due to extensive first-pass metabolism; therefore, not used orally.
Intranasal bioavailability is approximately 40-50% relative to intravenous administration; gastrointestinal absorption is limited due to first-pass metabolism, so oral bioavailability is <1%.
No dose adjustment required for renal impairment.
No dose adjustment required for renal impairment.
No dose adjustment required for hepatic impairment.
No dose adjustment required for mild to moderate hepatic impairment (Child-Pugh A or B); severe hepatic impairment (Child-Pugh C) has not been studied, use with caution.
Weight-based: <20 kg: 0.1 mg/kg IM/SC; ≥20 kg: 2 mg IM/SC; repeat every 2-3 minutes if needed.
Weight ≥30 kg: 5 mg intranasally as single dose; weight 10-30 kg: 2.5 mg intranasally as single dose; may repeat once after 2-3 minutes if needed.
No specific dose adjustment; use standard adult dosing with monitoring for adverse effects due to potential comorbidities.
No specific dose adjustment; elderly patients may be more sensitive to adverse effects, monitor for excessive sedation or respiratory depression.
Risk of recurrent respiratory depression: The duration of action of naloxone is shorter than that of most opioids, so repeat doses may be necessary. Patients should be monitored until respiratory function is fully recovered.
None.
May precipitate acute opioid withdrawal in opioid-dependent patients; risk of incomplete response or need for repeat doses due to short half-life; not effective for non-opioid overdoses; avoid in known hypersensitivity; use caution in patients with cardiovascular disease or those taking cardiotoxic drugs.
Risk of seizures, especially in patients with physical dependence on benzodiazepines, concurrent tricyclic antidepressant overdose, or history of seizures,Do not use for diagnostic purposes in suspected seizure disorders,May cause panic attacks in patients with anxiety disorders,Monitor for resedation due to shorter duration of action than benzodiazepines
Hypersensitivity to naloxone or any component of the formulation.
Known hypersensitivity to flumazenil or benzodiazepines,Patients receiving benzodiazepines for control of life-threatening conditions (e.g., increased intracranial pressure, status epilepticus),Evidence of serious tricyclic antidepressant overdose
None known; naloxone is not absorbed orally due to first-pass metabolism. No dietary restrictions.
No known food interactions with Kloxxado. Naloxone is not affected by food intake. Avoid alcohol or sedatives as they may exacerbate opioid effects.
EVZIO (naloxone) is not associated with major congenital malformations; limited data in pregnancy. Immediate reversal of opioid effects may precipitate withdrawal in the fetus, potentially causing adverse outcomes such as preterm labor or fetal distress. Third trimester use may cause neonatal opioid withdrawal syndrome (NOWS) in opioid-dependent mothers if naloxone is administered.
Pregnancy category D: Positive evidence of human fetal risk in first trimester (increased risk of oral clefts), second and third trimesters (risk of maternal and neonatal respiratory depression, neonatal withdrawal syndrome). Avoid in pregnancy unless benefit outweighs risk.
Naloxone is unlikely to be excreted in breast milk in significant amounts due to low bioavailability. M/P ratio not established. Preterm infusion studies show minimal transfer. Consider benefits of breastfeeding against risk of maternal opioid overdose reversal.
Excreted in breast milk; M/P ratio unknown. Potential for infant sedation and withdrawal. Use caution; consider alternative agents or monitor for drowsiness and feeding difficulties.
No pharmacokinetic studies in pregnancy demonstrate need for dose adjustment. Standard dosing (0.4 mg or 2 mg intranasal/IM) is used. Pregnant patients may require higher doses due to increased volume of distribution and metabolic changes, but evidence insufficient to recommend routine dose adjustment.
No standard dose adjustment recommended; however, pharmacokinetic changes (increased volume of distribution, altered clearance) may require higher or more frequent dosing to maintain efficacy. Individualize based on response and tolerance.
EVZIO is a naloxone auto-injector for emergency treatment of opioid overdose. Administer intramuscularly or subcutaneously into outer thigh; can be given through clothing. Repeat every 2-3 minutes if no response. Onset of action within 2-5 minutes. Duration shorter than most opioids; monitor for recurrence of respiratory depression. Not for non-opioid overdoses.
Kloxxado (naloxone) 8 mg nasal spray is FDA-approved for emergency treatment of opioid overdose. Use in patients with known or suspected opioid overdose, including respiratory depression. Onset within 2-3 minutes. May require repeat dosing due to shorter half-life than many opioids. Monitor for withdrawal precipitation. Store at room temperature; protect from light. Train caregivers and patients on proper administration.
Always call 911 immediately after giving EVZIO.,Place the device against the outer thigh and press firmly; it will automatically inject.,A short, clicking sound indicates the injection has started.,Stay with the person after injection; they may become agitated due to opioid withdrawal.,Store at room temperature; check expiration date regularly.,Tell family and friends where you keep EVZIO.
Administer as soon as opioid overdose is suspected: unresponsiveness, slow/stopped breathing, or pin-point pupils.,Spray one dose into one nostril; if no response in 2-3 minutes, give second dose in other nostril using a new device.,Call 911 immediately before or after administration; Kloxxado is a temporary measure.,Stay with patient until emergency help arrives; repeat doses may be needed if opioids are long-acting (e.g., fentanyl).,Side effects include acute withdrawal symptoms (nausea, vomiting, sweating, agitation, rapid heart rate).,Store at 68-77°F (20-25°C); do not freeze. Check expiration date.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about EVZIO vs KLOXXADO, answered by our medical review team.
EVZIO is a Opioid Antagonist that works by Naloxone is an opioid antagonist that competitively binds to mu-opioid receptors, reversing opioid-induced respiratory depression and analgesia.. KLOXXADO is a Opioid Antagonist that works by KLOXXADO (flumazenil) is a benzodiazepine antagonist that competitively inhibits the activity at the benzodiazepine binding site on the GABA-A receptor, thereby reversing the effects of benzodiazepines.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between EVZIO and KLOXXADO depend on the specific clinical indication. These are both Opioid Antagonist agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of EVZIO is: 2 mg intramuscular (IM) or subcutaneous (SC) autoinjector into anterolateral thigh; repeat every 2-3 minutes as needed for opioid overdose.. The standard adult dose of KLOXXADO is: 5 mg intranasally as a single dose; may repeat once after 2-3 minutes if response inadequate.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between EVZIO and KLOXXADO in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. EVZIO is classified as Category C. EVZIO (naloxone) is not associated with major congenital malformations; limited data in pregnancy. Immediate reversal of opioid effects may precipitate withdrawal in the fetus, pot. KLOXXADO is classified as Category C. Pregnancy category D: Positive evidence of human fetal risk in first trimester (increased risk of oral clefts), second and third trimesters (risk of maternal and neonatal respirato. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.