Liposomal Prilocaine Efficacy In Inferior Alveolar Nerve Block In Rats

Objective: This study evaluated the anesthetic efficacy of liposomal prilocaine in rats. Methods: Under general anesthesia, a cupper wire was fixed to the right and left mandibular molars of 30 Wistar rats. After the returning from the general anesthesia, the animals were sedated and the pulpal threshold of mandibular molars was assessed by the application of electric stimulus (pulp tester). The animals were randomly divided into 3 groups, which received an inferior alveolar nerve block in the right side with 0.2mL of the following formulations: 3% liposomal prilocaine; 3% plain prilocaine; and 3% prilocaine with 0.03UI/mL felypressin (Citocaina®). The contralateral side received the same volume of saline. After this procedure, the anesthesia success, onset and duration of pulpal anesthesia were evaluated by electric stimulus. Data were submitted to Kruskal-Wallis (onset and duration of anesthesia) and Log Rank (anesthesia success) tests (alpha=5%). Results: (Table). Liposomal prilocaine presented higher (p<0.05) anesthesia success than plain prilocaine at 15 and 20 minutes; prilocaine with felypressin presented higher (p<0.05) anesthesia success than plain prilocaine at 15, 20 and 25 minutes after the injection. No differences were observed between liposomal prilocaine and prilocaine with felypressin regarding anesthesia success and duration of anesthesia (p>0.05). No differences were observed among the formulations in relation to onset of anesthesia (p>0.05). Conclusion: Liposomal prilocaine presented similar anesthetic efficacy of prilocaine with felypressin and both formulations showed increased anesthesia success and duration of anesthesia when compared to the plain prilocaine solution. Supported by FAPESP (#2006/00121-9).

Table. Success (%), onset and duration (median and interquartile range, in minutes) of anesthesia.