Additives to local anesthetics for peripheral nerve blockade.

Many additives to local anesthetics to prolong the duration of analgesia for peripheral nerve blocks have been studied. In this review, the authors focus on the more commonly described additives, including epinephrine, clonidine, dexmedetomidine, buprenorphine, dexamethasone, tramadol, sodium bicarbonate, and midazolam. While the primary focus of this review is the effect of the additive on the duration of analgesia, neurotoxicity and other safety concerns are also discussed.