Enhancement of bupivacaine toxicity by diltiazem in anaesthetized dogs

Safety of amide local anesthetics: new trends

IMPORTANCE OF THE FIELD

Local anesthetics have become one of the most common drugs used in daily practice worldwide. Neurologic and cardiovascular events are the most frequent adverse reactions related to local anesthetics use. Recently, new trends have been developed on this topic.

AREAS COVERED IN THIS REVIEW

We performed an overview of the data available so far on local anesthetics adverse reactions. Relevant literature was identified using PubMed search of articles published up to November 2009, including experimental studies, case reports or clinical studies when available. Search terms included: 'local anaesthetics', 'adverse drug reaction', 'pharmacovigilance' and 'complication'.

WHAT THE READER WILL GAIN

Neurologic, cardiovascular and allergic reactions remain the most frequent adverse drug reactions related to local anesthetics in the literature. Studies based on pharmacovigilance systems have highlighted the frequency of adverse reactions little known until now, such as failure of block. Lipid emulsions are included into algorithm for cardiac resuscitation. Recent studies have demonstrated the myotoxicity and chondrotoxic effects of long-acting local anesthetics.

TAKE HOME MESSAGE

Physicians must keep in mind all these adverse reactions to better prevent their occurrence and give the most appropriate treatment.

The effects of verapamil and nimodipine on bupivacaine-induced cardiotoxicity in rats: an in vivo and in vitro study

The purpose of this in vivo and in vitro study was to compare the effects of verapamil or nimodipine pretreatment on bupivacaine-induced cardiotoxicity. In the in vivo study, the dose-response curve for the 50% lethal dose (LD50) of bupivacaine was determined for rats. Two separate groups of rats were pretreated with i.v. verapamil 150 microg/kg (n = 35) or i.v. nimodipine 200 microg/kg (n = 35). Each pretreatment group was then subdivided into four groups of at least four rats each. Three minutes after pretreatment, bupivacaine was administered to each of four groups in doses of 2.5, 3.0, 3.25, and 3.5 mg/kg, respectively. Both verapamil and nimodipine pretreatment increased the LD50 and 95% confidence intervals for bupivacaine and increased survival. In the in vitro study, the effects of verapamil or nimodipine perfusion on bupivacaine cardiotoxicity (negative chronotropic, negative inotropic, and arrhythmogenic effects) and coronary perfusion pressure (CPP) were investigated in isolated, perfused rat heart preparations. Depression of heart rate, contractile force, and CPP, and the incidence of arrhythmias caused by bupivacaine alone were similar to those caused by bupivacaine after verapamil pretreatment. In contrast, bupivacaine induced less negative chronotropic effects (P < 0.05, paired t-test) and arrhythmias (P < 0.05, chi2 analysis) after nimodipine pretreatment. The results of this study demonstrate that both verapamil and nimodipine pretreatment decrease bupivacaine-induced cardiotoxicity in vivo, whereas only nimodipine pretreatment decreased bupivacaine-induced cardiotoxicity and arrhythmias in vitro.

IMPLICATIONS

In this experimental study consisting of two stages (in vivo and in vitro), we compared the effects of two calcium channel-blocking drugs (verapamil and nimodipine) on bupivacaine toxicity. Bupivacaine is a local anesthetic frequently used in clinical practice, and cardiotoxicity is one of its severe side effects. Verapamil and nimodipine were both effective in decreasing bupivacaine cardiotoxicity in this rat model.

Effects of calcium channel blockers on bupivacaine-induced toxicity

The purpose of this study was to investigate the influence of calcium channel blockers on bupivacaine-induced acute toxicity. For each of the three tested calcium channel blockers (diltiazem, verapamil and bepridil) 6 groups of mice were treated by two different doses, i.e. 2 and 10 mg/kg/i.p., or an equal volume of saline for the control group (n = 20); 15 minutes later, all the animals were injected with a single 50 mg/kg/i.p. dose of bupivacaine. The convulsant activity, the time of latency to convulse and the mortality rate were assessed in each group. The local anesthetic-induced mortality was significantly increased by the three different calcium channel blockers. The convulsant activity of bupivacaine was not significantly modified but calcium channel blockers decreased the time of latency to obtain bupivacaine-induced convulsions; this effect was less pronounced with bepridil.