The Local Pharmacokinetics of 3H-Ropivacaine and 14C-Lidocaine After Maxillary Infiltration Anesthesia in Rats

The effects of infiltration anesthesia with ropivacaineon the dental pulp are considered to be weak. This may be partly associated with its permeation into the oral tissue. With the objective of investigating the local pharmacokinetics of ropivacaineand lidocainefollowing infiltration anesthesia, we injected 3H- ropivacaineor 14C- lidocaineto the palatalmucosa in rats, measured distributions of radioactivity in the maxilla, and compared the local pharmacokinetics of these agents. The animals were sacrificed at various times and the maxillaswere removed. The palatalmucosa and maxillary nervewere resected, and the bone was divided into 6 portions. We measured radioactivity in each tissue and calculated the level of each local anesthetic(n  =  8). Lidocainediffused to the surrounding tissue immediately after the injection, whereas ropivacainetended to remain in the palatalmucosa for a longer period. Lidocaineshowed a higher affinity for the maxillary bone than ropivacaine. There was a correlation...