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Erschienen in:
01.12.2005 | Adis Drug Evaluation
Ropivacaine
A Review of its Use in Regional Anaesthesia and Acute Pain Management
Erschienen in: Drugs | Ausgabe 18/2005
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Abstract
Ropivacaine (Naropin®) is the pure S(−)-enantiomer of propivacaine, and is a long-acting amide local anaesthetic agent, eliciting nerve block via reversible inhibition of sodium ion influx in nerve fibres.
Ropivacaine is a well tolerated regional anaesthetic effective for surgical anaesthesia as well as the relief of postoperative and labour pain. The efficacy of ropivacaine is similar to that of bupivacaine and levobupivacaine for peripheral nerve blocks and, although it may be slightly less potent than bupivacaine when administered epidurally or intrathecally, equi-effective doses have been established. Clinically adequate doses of ropivacaine appear to be associated with a lower incidence or grade of motor block than bupivacaine. Thus ropivacaine, with its efficacy, lower propensity for motor block and reduced potential for CNS toxicity and cardiotoxicity, appears to be an important option for regional anaesthesia and for the management of postoperative and labour pain.
Pharmacological Properties
Like other local anaesthetics, ropivacaine elicits nerve block via reversible inhibition of sodium ion influx in nerve fibres. The pKa of ropivacaine is similar to that of bupivacaine and levobupivacaine (≈8.2) but, unlike racemic bupivacaine, ropivacaine is the pure S(−)-enantiomer of propivacaine. It has lower lipid solubility and is less likely than bupivacaine to penetrate large, myelinated motor fibres. The degree of ropivacaine-induced sensory and motor block are dose- and age-dependent.
Despite the lower potency (based on minimum local anaesthetic concentrations) of ropivacaine than bupivacaine or levobupivacaine at lower doses, such as those used for epidural or intrathecal analgesia, ropivacaine has similar efficacy to these agents at higher doses such as those used for peripheral nerve block.
As with other local anaesthetics, ropivacaine has the potential to induce cardiovascular toxicity (e.g. arrhythmias and reduced myocardial conductivity and contractility) and CNS toxicity (e.g. seizures) at high plasma concentrations such as those occurring after large doses or inadvertent intravascular administration. It has a significantly higher threshold for cardiovascular and CNS toxicity than bupivacaine in animals and healthy volunteers.
Ropivacaine displays linear and dose-proportional pharmacokinetics up to 80mg (when administered intravenously). Absorption from the epidural space is complete and biphasic; the first phase (half-life [t;] 14 minutes) is followed by a slower second phase (t; 4.2 hours). Ropivacaine is extensively protein bound and crosses the placenta during epidural administration for Caesarean section. It is metabolised in the liver and excreted in the urine.
Therapeutic Efficacy
Randomised, double-blind, comparative clinical trials in adults have demonstrated the efficacy of ropivacaine in providing a profound sensory and motor block suitable for anaesthesia and a sensory/motor block profile suitable for postoperative or labour pain when administered by various routes (principally epidural or intrathecal administration and peripheral nerve block).
For epidurally administered surgical anaesthesia, ropivacaine and bupivacaine have similar efficacy, whereas with epidural administration for postoperative or labour analgesia, where doses required are lower than those needed for anaesthesia, ropivacaine has a shorter-lasting sensory block as well as a lower incidence/ degree of motor block than bupivacaine; equipotent doses have been established.
The duration of analgesia was less with ropivacaine than bupivacaine when administered intrathecally for anaesthesia or labour pain relief, but the duration of sensory block is still adequate for anaesthesia and the quicker regression of the motor block encourages mobilisation and recovery.
Peripheral nerve block for anaesthesia in orthopaedic surgery and for postoperative pain relief requires the use of relatively high doses of regional anaesthetic agents and the potency differences between ropivacaine and bupivacaine that were evident with epidural or intrathecal administration were not observed with this route of administration.
Ropivacaine and levobupivacaine are generally similarly effective for the above indications and routes of administration.
In children aged <12 years, ropivacaine provided effective postoperative pain relief when administered as a caudal or lumbar epidural injection, as a continuous epidural infusion or as a peripheral nerve block. The analgesic efficacy of ropivacaine was similar to that of bupivacaine and levobupivacaine; however, postoperative motor blockade was significantly less in ropivacaine than in bupivacaine recipients.
Tolerability
Ropivacaine is generally well tolerated regardless of the route of administration. Adverse events that occurred in ≥5% of patients in clinical trials who received ropivacaine 0.125–1% via various routes of administration for surgery, labour, Caesarean section, postoperative pain management, peripheral nerve block or local infiltration were hypotension (32%), nausea (17%), vomiting (7%), brady-cardia (6%) and headache (5%). Epidural administration of ropivacaine for surgery produced dose-dependent adverse events similar to those observed with equal doses of bupivacaine. Ropivacaine is generally well tolerated in the fetus or neonate following maternal epidural administration. The incidence of cardiovascular and CNS toxicity as a result of inadvertent intravascular injection of ropivacaine appears to be low.
The tolerability of ropivacaine in children (aged from 1 month to 15 years) appears to be at least similar to that of bupivacaine or levobupivacaine and is generally good, regardless of the route of administration. The most frequently occurring adverse events were nausea and vomiting.