The aim of this study was to investigate the role of stress (trauma, cold swimming, and adjuvant rheumatoid arthritis) on lidocaine concentrations as well as lidocaine's protein binding in the mandible.
Forty male Wistar rats were used. The animals were divided into four groups. Group A served as control. Group B underwent mandible osteotomy. Group C was submitted to cold swimming stress. Group D was subjected to experimental arthritis. Additionally, all the groups received 5 doses of lidocaine, 1 dose of lidocaine (3 mg/kg) intramuscularly every 2 hours. Two hours after the last dose, the animals were killed. Lidocaine concentrations were estimated in plasma. Furthermore, the mandible was isolated, and both lidocaine concentrations and lidocaine protein binding were assessed.
In groups under stress, lidocaine concentrations in serum showed a marked elevation. In addition, these animals demonstrated a significant decrease in the percent of lidocaine binding in the mandible.
Stress can modify local anesthetics pharmacokinetic properties, resulting in alterations both in their concentration in serum and their protein binding in mandibular bone.