Pharmacokinetics of Levobupivacaine, Fentanyl, and Clonidine After Administration in Thoracic Paravertebral Analgesia

After paravertebral bolus and infusion administration, Cpmax levobupivacaine was within the safe range. Cpmax fentanyl and clonidine were less than the effective levels after IV administration, suggesting that their analgesic effect may be partly attributed to a peripheral mechanism of action.