Ropivacaine (Naropin)

Anesthesia Implications

Classification: Amino amide local anesthetic
Therapeutic Effects: Local Anesthesia, regional anesthesia, sympathetic blockade
Time to Onset: Infiltration: 1-15 min; Epidural: 10-20 min; Spinal: less than 2 min.
Time to Peak: Infiltration: 20-45 min; Epidural: 20-45 min; Spinal: 10-13 min.
Duration: Infiltration: 120-400 min; Epidural: 120-400 min; Spinal: 120 min;

Contraindications

ABSOLUTE for epidural, caudal, or intrathecal injection: hypovolemic shock, septicemia, infection at injection site, or coagulopathy.
Relative: Hypovolemia, severe congestive heart failure, shock, or exhibiting any form of heart block.

Primary Considerations

Max dose – 3 mg/kg with or without epinephrine.

Naropin vs Bupivacaine – For motor blockade, the duration is shorter and less intense when compared to bupivacaine. For sensory blockade, the depth, duration, and onset is similar to bupivacaine. Ropivacaine has decreased risks of arrhythmias and cardiodepressant effects at RECOMMENDED doses. Above recommended doses, those advantages may be negated.

Interscalene blockade – use of 0.2% ropivacaine (vs 0.1%) results in reduced forced vital capacity (FVC) and forced expiratory volume (FEV1), with no significant differences in pain scores, length of stay, or total opioid consumption in the PACU. However, use of the 0.2% concentration does extend the duration of the block (18 vs 11.9 hours) and leads to a decreased need for opioids in the 72 hours following surgery (55mg vs 102mg of codeine).

Working IV – Ensure there’s a working IV before performing any major regional block using Naropin.

Accidental Subarachnoid Injection – if this happens while administering epidural administration, it may result in persistent anesthesia, parethesia, weakness/paralysis of lower extremeties, and loss of sphincter control. These symptoms may have slow/no recovery.

IV regional anesthesia (eg. Bier block) – NOT recommended. High plasma concentrations following the release of the tourniquet have resulted in cardiac arrest/death.

Vasoconstrictor – Amongst the array of local anesthetics, ropivacaine has a unique attribute of being a vasoconstrictor. The addition of epinephrine will improve the quality of the analgesia, but will NOT extend or reduce the duration, systemic absorption, or onset time.

OB – Dose requirements are reduced in the parturient. At high plasma levels, ropivacaine causes uterine vasoconstriction, reduced uterine blood flow, and fetal bradycardia/death. This is seen in cases such as paracervical blocks, NOT with epidurals or spinals. Therefore, ropivacaine is not recommended for paracervical blocks. When given in equally potent doses as bupivacaine, ropivacaine has not been shown to prolong the duration of labor, influence the mode of delivery, or cause adverse neonatal outcomes.

Concentrations – 0.2%, 0.5%, 0.75%, 1%.

Discard – Naropin should be discarded after use or within 24 hours after the vial/ampule has been opened. This is also true for any continuous-infusion bottles.

Renal Failure – Renal failure results in higher plasma concentrations and duration of action. Dose judiciously and watch closely for signs of toxicity.

Toxicity – Early signs: tongue/circumoral numbness, metallic taste, restlessness, tinnitus, tremors, blurred vision. Late signs include siezures, respiratory depression, and circulatory depression/arrest. See the heading “Reversal” to treat toxicity.

Hypotension and Bradycardia – Epidural or intrathecal ropivacaine administration will often result in hypotension and/or bradycardia. The degree is determined by the level of sympathetic blockade. Blockade above T5 will result in bradycardia. Treatment/prophylaxis includes fluid hydration (10-20 ml/kg of NS or LR), vasopressors (eg. ephedrine), and left uterine displacement (for the parturient). Bradycardia can be treated with muscarinic antagonists (eg. glycopyrrolate, atropine).

Drug interactions – Theophylline, imipramine, verapamil, and fluvoxamine will reduce clearance of ropivacaine. Other amide-type local anesthetics will have an additive toxic affect. Volatile anesthetics, benzodiazepines, and barbiturates will increase the seizure threshold.

Reversal

Toxicity – 20% Lipid emulsion (intralipid). 1-2 ml/kg bolus followed by a 0.25 ml/kg/min infusion for 30-60 minutes. Bolus doses can be repeated every 3-5 minutes to a max of 4 ml/kg. Administration of lipid rescue should be considered BEFORE ceasing resuscitation efforts, even if administration is late in those efforts. If sodium channel blockade is suspected as the source of cardiac toxicity, sodium bicarbonate can be administered (1-2 mEq/kg). Seizures or seizure prophylaxis can be treated with Versed (0.2 mg/kg IM, or 0.02-0.1 mg/kg IV).

Epidural MOTOR Blockade – administration of 20 mL of 0.9% saline.

Method of Action

Naropin stabilizes neuronal membranes by blocking both the generation and conduction of nerve impulses. The progression of
anesthesia is related to the diameter, myelination and conduction velocity of affected nerve fibers. Clinically, the order of loss of nerve function is as follows: (1) pain, (2) temperature, (3) touch, (4) proprioception, and (5) skeletal muscle tone.

Metabolism

Extensively hepatic (cytochrome P4501A).

Elimination

Renal

Additional Notes
Ropivacaine was developed to address the cardiotoxicity seen with bupivacaine.