Effects of vasopressin on anesthetic response time and circulatory dynamics of lidocaine

This study aimed to investigate the hypothesis that vasopressin extends the anesthetic response time of lidocaine and does not affect the circulatory dynamics. Rats were sedated with isoflurane; subsequently, breathing was maintained through mechanical ventilation. We infiltrated the first molar area of the upper left jaw with saline (NS, test solution), 2% lidocaine (L), 0.025 IU vasopressin-supplemented 2% lidocaine, 0.05 IU vasopressin-supplemented 2% lidocaine, 0.1 IU vasopressin-supplemented 2% lidocaine, and 0.2 IU vasopressin-supplemented 2% lidocaine (VL(4)). Further, anesthetic response times were measured up to 30 min using electric pulp testing methods (n = 4). The anesthetic response times of NS, L, and VL(4) were measured up to 45 min with the aforementioned results as reference values (n = 7). The circulatory dynamics of NS, L, VL(4), and 0.2 IU vasopressin (V) were measured up to 45 min using a non-invasive blood pressure measuring device. VL(4) extended the anesthetic response times of lidocaine compared to L (p < 0.05). Further, V and VL(4) significantly increased the systolic and diastolic blood pressure and significantly decreased the pulse rate (p < 0.05). VL(4) is not a suitable addition to the local anesthetic solution used in dentistry. Further study is needed to determine vasopressin concentration that extends the anesthetic effect without affecting the circulatory dynamics.