Dose-dependent suppression of the neutrophil respiratory burst by lidocaine

Background: Oxygen radical production is thought to be fundamental to the pathogenesis of post-ischaemic reperfusion injury which is routinely managed with lidocaine. Attention has, therefore, focused on the suppression of the neutrophil respiratory burst with a therapeutic endpoint. The widest application of lidocaine remains in local analgesia. Methods: A standard chemiluminescence technique was used to assess the human neutrophil leukocyte response to increasing doses of lidocaine in the presence or absence of particulate hydroxyapatite. Results: No reduction of oxygen radical production was seen at the drug concentration of 1 mg/ml. A clear, concentration-dependent inhibition was seen at 2 mg/ml, 3 mg/ml, 4 mg/ml and 8 mg/ml concentrations. These drug concentrations may be reached at or near the site of injection in local anaesthetic use. Conclusion: Lidocaine showed profound anti-inflammatory action in this experimental system. Controlled studies in the clinical setting would identify the optimal analgesic and anti-inflammatory dosage, whilst preserving host defence without compromising tissue repair.