Chirocaine (Abbott)
10 mL ampoules containing 2.5 mg/mL, 5 mg/mL and
7.5 mg/mL
Approved indication: anaesthesia
Australian Medicines Handbook Section 2.1
Bupivacaine is an amide-type local anaesthetic. Although it blocks neuro transmission, its membrane stabilising action also affects the myocardium. This can cause fatal cardiotoxicity. As bupivacaine is widely used in surgery and obstetrics, attempts have been made to develop a safer long-acting local anaesthetic.
The bupivacaine molecule is a racemic compound. Levobupivacaine is the S-enantiomer of bupivacaine and is thought to have less cardiotoxic potential than the R-enantiomer. The pharmacokinetic parameters of levobupivacaine are similar to those of bupivacaine.
Levobupivacaine has been studied in surgical anaesthesia and for pain management. It can be used for local infiltration, epidural, intrathecal and peripheral nerve blocks. For epidural analgesia it can be given with fentanyl, morphine or clonidine. Double-blind comparisons of levobupivacaine and bupivacaine show that their anaesthetic effects are similar.
The adverse effects of the two drugs are also similar. They are influenced by how the drugs are administered, for example hypotension often occurs during epidural anaesthesia. Nausea and vomiting also occur commonly with both drugs.
To reduce adverse effects the smallest dose and concentration should be used. The 7.5 mg/mL concentration should not be used in children or in obstetrics. Like bupivacaine intravascular injection must be avoided, and levobupivacaine is contraindicated for intravenous regional anaesthesia (Bier's block) because of cardiotoxicity. It is also contraindicated as a paracervical block. Test doses with a short-acting local anaesthetic can be used before using levobupivacaine for a complete nerve block. Although animal studies suggest a benefit, it remains to be proven whether levobupivacaine has significantly less toxicity than bupivacaine.
