Liposomal bupivacaine as a single-injection peripheral nerve block: a dose-response study

Area of Science:

• Anesthesiology
• Pharmacology
• Pain Management

Background:

• Current local anesthetics for peripheral nerve blocks offer durations under 24 hours.
• A liposomal bupivacaine formulation is approved for wound infiltration, not nerve blocks.
• This study investigates its potential for extended peripheral nerve blockade.

Purpose of the Study:

• To evaluate the efficacy and duration of liposomal bupivacaine for femoral nerve blocks.
• To assess sensory and motor blockade characteristics in healthy volunteers.

Main Methods:

• Bilateral single-injection femoral nerve blocks were performed on 14 healthy volunteers.
• Liposomal bupivacaine doses (0-80 mg) were administered and mixed with saline.
• Outcomes measured included quadriceps muscle maximum voluntary isometric contraction (MVIC) and electrical current tolerance.

Main Results:

• A dose-response relationship was observed for MVIC and current tolerance, though inversely to expectations.
• Peak effects occurred within 24 hours for most subjects.
• Blockade duration exceeded 24 hours for doses above 40 mg, with MVIC and sensory recovery often delayed.

Conclusions:

• Liposomal bupivacaine may provide sensory and motor blockade exceeding 24 hours when used for femoral nerve blocks.
• High inter-subject variability and an inverse dose-response suggest caution.
• A larger Phase 3 study is required for confirmation.