Figure 5. Duration of nerve blockade produced by free and liposomal bupivacaine (0.75%). Recovery of tactile response was determined after administration of either free bupivacaine (closed triangle); bupivacaine in control liposomes (no pH gradient; open circle); or bupivacaine in pH gradient liposomes (closed square). Saline and empty liposome controls were also performed (not shown), and these exhibited no nerve block. The error bars indicate standard error; n = 12.