Analgesic responses to i.v. lignocaine

Area of Science:

• Anesthesiology
• Neurology
• Pharmacology

Background:

• Neuralgic pain presents diverse etiologies.
• Intravenous lignocaine is a local anesthetic with potential systemic effects.
• Understanding lignocaine's differential analgesic effects is clinically relevant.

Purpose of the Study:

• To evaluate the analgesic efficacy of intravenous lignocaine in patients with neuralgic pain.
• To compare lignocaine's effect on clinical neuralgic pain versus experimentally induced ischemic pain.
• To investigate the dose-dependent and pain-type-specific actions of lignocaine.

Main Methods:

• Five patients with neuralgic pain were administered intravenous lignocaine.
• Pain intensity was assessed for both clinical neuralgic pain and concurrently induced ischemic pain.
• Lignocaine was administered in a high-dose infusion followed by lower doses, with corresponding blood concentrations monitored.

Main Results:

• High-dose lignocaine (3 mg kg-1) reduced both clinical and ischemic pain, with a significantly greater reduction in clinical pain.
• At lower doses, lignocaine effectively suppressed clinical neuralgic pain but had no significant effect on ischemic pain.
• Clinical neuralgic pain was almost totally suppressed at lower lignocaine concentrations compared to its lack of effect on ischemic pain.

Conclusions:

• Intravenous lignocaine exhibits a differential analgesic effect based on pain etiology.
• Lignocaine appears particularly effective for deafferentation pain and central neuralgias.
• Peripheral pain of origin is largely unaffected by lignocaine, except at potentially toxic concentrations.