Lignocaine vs bupivacaine in prominent ear correction: a controlled trial

In the sole direct infiltration trial, 0.25% bupivacaine halved early opioid rescue (2 of 15 versus 7 of 15 children in the first 4 hours) compared with 1% lidocaine.

“In the sole direct infiltration trial, 0.25% bupivacaine halved early opioid rescue (2 of 15 versus 7 of 15 children in the first 4 h) and maintained effective analgesia for 8 hours or more, whereas 1% lidocaine lost effect within 4 hours despite similar late-evening pain scores.16”

0.25% bupivacaine maintained effective analgesia for 8 hours or more, whereas 1% lidocaine lost effect within 4 hours despite similar late-evening pain scores.

“In the sole direct infiltration trial, 0.25% bupivacaine halved early opioid rescue (2 of 15 versus 7 of 15 children in the first 4 h) and maintained effective analgesia for 8 hours or more, whereas 1% lidocaine lost effect within 4 hours despite similar late-evening pain scores.16”

Bupivacaine's slower dissociation from axonal Na+ channels explains the extended coverage of regional nerve block, whereas lidocaine typically wears off after 2-4 hours.

“This extended coverage reflects bupivacaine’s slower dissociation from axonal Na⁺ channels, whereas lidocaine, the agent most often used for LIA, typically wears off after 2–4 hours.16”

The direct infiltration trial result is vulnerable to "duration bias," favoring the molecule rather than the infiltration technique itself.

“Because the comparator was a short-acting drug, this result is vulnerable to “duration bias,” favoring the molecule rather than the infiltration technique itself.16”

Bupivacaine's slower voltage-gated Na+ channel off-rate (τ ≈ 50 versus ≈ 10 min for lidocaine) produces a 4- to 8-hour sensory block and explains the "duration bias" noted by Roberts et al.

“The pharmacological advantage derives from bupivacaine’s slower voltage-gated Na⁺ channel off-rate (τ ≈ 50 versus ≈ 10 min for lidocaine), producing a 4- to 8-hour sensory block and explaining the “duration bias” noted by Roberts et al.16,24,25”

The single lidocaine-versus-bupivacaine trial is subject to "duration bias," as distinct Na+-channel binding kinetics confound any anatomical effect.

“Finally, the single lidocaine-versus-bupivacaine trial is subject to “duration bias,” as distinct Na⁺-channel binding kinetics confound any anatomical effect, and the favorable safety signal for transdermal hyoscine derives from just 1 pediatric RCT.”