Duration of action of nerve blocks produced by mixtures of local anesthetics and low molecular weight dextran: studies in rat infraorbital nerve blocks.

The duration of rat infraorbital nerve block by 1% lidocaine or 0.25% bupivacaine, and its modification by low molecular weight dextran, was investigated in a randomized, observer-blind study. The addition of low molecular weight dextran did not prolong the duration of the blocks. No evidence of slow releasing or local anesthetic binding properties attributed to low molecular weight dextran was found.