NAROPIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NAROPIN (NAROPIN).
Ropivacaine blocks sodium ion channels in neuronal cell membranes, inhibiting the conduction of nerve impulses.
| Metabolism | Primarily hepatic via CYP1A2 and CYP3A4; metabolized to 3-hydroxy-ropivacaine and other metabolites. |
| Excretion | Renal: 86-93% as metabolites (including 3-hydroxyropivacaine, 4-hydroxyropivacaine, and 2',6'-pipecoloxylidide), <1% unchanged. Biliary/fecal: <10% collectively, primarily as metabolites. |
| Half-life | Terminal elimination half-life: 4.2 ± 1.1 hours (adults) for ropivacaine. Clinical context: prolonged half-life in neonates (up to 12-18 hours) due to immature hepatic clearance; consider accumulation with continuous infusion in renal impairment (though minimal unchanged drug). |
| Protein binding | 94% bound primarily to alpha-1-acid glycoprotein (AAG) and, to a lesser extent, albumin. Note: binding is concentration-dependent; at high concentrations (above 1 µg/mL), binding decreases, increasing free fraction and potential toxicity. |
| Volume of Distribution | Steady-state volume of distribution (Vdss): 0.59 L/kg (range 0.41-0.84 L/kg) in adults. Clinical meaning: moderate distribution, reflecting distribution to well-perfused tissues; higher in neonates (1.4-2.5 L/kg) due to increased body water and lower AAG levels. |
| Bioavailability | Epidural: 98% (systemic absorption is nearly complete). Intrathecal: ~100% (directly into CSF). Subcutaneous infiltration: ~100% (absorbed into systemic circulation). Oral: not available (low bioavailability due to extensive first-pass metabolism). |
| Onset of Action | Epidural (lumbar): 15-30 minutes for surgical anesthesia. Peripheral nerve block: 15-30 minutes (depending on technique). Subcutaneous infiltration: 1-5 minutes. Intrathecal: 5-15 minutes. |
| Duration of Action | Epidural (surgical anesthesia): 2-6 hours (dose-dependent). Peripheral nerve block: 4-12 hours (with epinephrine may extend to 12-18 hours). Subcutaneous infiltration: 2-4 hours. Clinical notes: duration increases with higher concentration (0.5% > 0.2%) and addition of epinephrine (prolongs sensory block but not motor). |
| Molecular Weight | 274.4 |
Epidural administration: Initial dose 20-30 mL of 0.5% solution (100-150 mg) followed by 10-15 mL/hour of 0.2% solution for continuous infusion. Maximum single dose: 200 mg. Maximum daily dose: 400 mg.
| Dosage form | SOLUTION |
| Renal impairment | No specific dose adjustment required for GFR ≥30 mL/min. For GFR <30 mL/min, use with caution and consider reducing dose by 25-50% due to potential accumulation of metabolites. |
| Liver impairment | Child-Pugh A: No adjustment necessary. Child-Pugh B: Reduce dose by 50% and monitor for toxicity. Child-Pugh C: Contraindicated due to risk of severe toxicity. |
| Pediatric use | Epidural bolus: 0.5-1 mg/kg of 0.2-0.5% solution. Continuous infusion: 0.2-0.4 mg/kg/hour of 0.1-0.2% solution. Maximum single dose: 2 mg/kg. Not recommended for infants under 1 year due to limited data. |
| Geriatric use | Initial dose should be reduced by 20-30% due to decreased clearance and increased sensitivity. Titrate carefully with lower infusion rates (e.g., 5-10 mL/hour of 0.2% solution) and monitor for hypotension and bradycardia. |
| 1st trimester | No well-controlled studies; use only if clearly needed. Local anesthetic with low systemic toxicity. Reports of teratogenicity not established. |
| 2nd trimester | Use with caution; monitor for maternal hypotension and fetal bradycardia. May cross placenta. Fetal acidosis can reduce protein binding. |
| 3rd trimester | Use with caution in labor; can cause uterine hyperactivity and fetal bradycardia. Avoid with non-reassuring fetal status. |
Clinical note
Comprehensive clinical and safety monograph for NAROPIN (NAROPIN).
| Placental transfer | Crosses placenta; fetal/maternal ratio ~0.3-0.4. Less accumulation than bupivacaine. |
| Breastfeeding | Ropivacaine is excreted into breast milk in small amounts. Risk to infant is low; minimal systemic absorption expected. Compatible with breastfeeding. |
■ FDA Black Box Warning
Not approved for use in children under 12 for neuraxial anesthesia due to risk of serious adverse effects.
| Serious Effects |
Hypersensitivity to ropivacaine or any amide-type local anestheticSevere hypotensionCardiogenic or hypovolemic shockSevere bradycardiaAdvanced heart block
| Precautions | Risk of cardiac arrest and seizures with high doses or inadvertent intravascular injection, May cause methemoglobinemia |
| Food/Dietary | No known food interactions. Grapefruit juice may theoretically increase systemic absorption via inhibition of CYP1A2, but clinical significance is minimal with single-dose administration. Maintain normal diet unless otherwise instructed. |
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| Lactation Rating |
| L2 (Limited data - probably compatible) |
| Teratogenic Risk | Naropin (ropivacaine) is a local anesthetic of the amide type. No adequate and well-controlled studies in pregnant women. Animal studies have not shown teratogenic effects at doses up to 1.3 mg/kg (rabbit) and 7.3 mg/kg (rat). However, ropivacaine crosses the placenta rapidly and may cause fetal bradycardia, acidosis, and central nervous system depression if high maternal levels occur. First trimester: risk cannot be ruled out, but no evidence of structural anomalies. Second and third trimesters: potential for fetal distress due to maternal hypotension or uterine hypoperfusion from sympathetic blockade; use only if clearly needed. |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and oxygen saturation continuously during administration. Fetal heart rate monitoring should be performed when possible, especially during epidural or spinal anesthesia. Observe for signs of maternal hypotension, which can reduce uterine blood flow. Monitor for fetal bradycardia, as local anesthetics can cross the placenta. After delivery, monitor neonate for signs of local anesthetic toxicity (e.g., apnea, bradycardia, seizures). |
| Fertility Effects | No specific studies on human fertility. Animal studies (rat) showed no significant effects on male or female fertility at doses up to 7.3 mg/kg. It is not known whether ropivacaine affects human fertility. Based on mechanism, no expected impact on fertility when used at recommended doses. |
| Clinical Pearls |
| NAROPIN (ropivacaine) is a long-acting amide local anesthetic with a reduced cardiac toxicity profile compared to bupivacaine due to lower lipophilicity. It provides differential sensory and motor block, making it ideal for labor analgesia and postoperative pain management. For epidural use, test dose with 3 mL of 0.5% ropivacaine + epinephrine 1:200,000 to rule out intravascular injection. Maximum single dose is 225 mg (3 mg/kg) for surgical anesthesia; for continuous infusion, maximum 800 mg/24 hours. Use with caution in patients with hepatic impairment due to metabolism via CYP1A2. |
| Patient Advice | Report any signs of allergic reaction such as rash, itching, or difficulty breathing immediately. · You may experience numbness or weakness in the injected area; avoid driving or operating machinery until full sensation returns. · Inform your healthcare provider if you have liver disease, heart problems, or are taking other medications, especially antiarrhythmics. · Do not apply heat or ice directly to the injection site without consulting your doctor. · Contact your doctor if numbness, pain, or redness persists beyond the expected duration. |