Felypressin, but not epinephrine, reduces myocardial oxygen tension after an injection of dental local anesthetic solution at routine doses.

PURPOSE The aim of this study was to evaluate the effect of epinephrine (Epi) or felypressin (Fely) contained in dental local anesthetics on myocardial oxygen balance. MATERIALS AND METHODS Male Japanese White tracheotomized rabbits were anesthetized with isoflurane. Three doses of 0.18, 0.36, and 0.72 mL of 2% lidocaine hydrochloride containing 1:80,000 Epi or 3% prilocaine hydrochloride containing Fely 0.03 IU/mL were injected into the rabbit tongue muscle. These doses were equivalent to 2, 4, and 8 of dental local anesthetic cartridges in humans weighing 50 kg by body weight correction, respectively. Heart rate, blood pressure, aortic blood flow, myocardial tissue blood flow, and myocardial tissue oxygen tension were continuously monitored. Data were recorded immediately before and 10, 20, 30, and 60 minutes after the injection. RESULTS Heart rate decreased in the Fely group. Systolic blood pressure increased in the Epi group, and diastolic blood pressure increased in both groups. Aortic blood flow and myocardial tissue blood flow increased, whereas myocardial tissue oxygen tension did not change in the Epi group. In contrast, aortic blood flow, myocardial tissue blood flow, and myocardial tissue oxygen tension decreased in the Fely group. CONCLUSION It is suggested that Fely, but not Epi, decreases myocardial oxygen tension and aggravates myocardial oxygen demand/supply balance even after an injection of dental local anesthetic solution at routine doses.