Absorption of injected local anesthetics depends on various factors. Fastest route of absorption of local anaesthetic is:
The rate of systemic absorption is propoionate to the vascularity of the site of injection: intravenous > tracheal > intercostal > caudal > paracervical > epidural > brachial plexus > sciatic > subcutaneous. Ref: Morgan, Jr. G.E., Mikhail M.S., Murray M.J. (2006). Chapter 14. Local Anesthetics. In G.E. Morgan, Jr., M.S. Mikhail, M.J. Murray (Eds), Clinical Anesthesiology, 4e.
Intercostal
Epidural
Brachial
Caudal