Formulation and evaluation of multilamellar vesicles ropivacaine in pain management

Purpose: The improvement of postoperative pain control plays an important role in recovery outcomes and patient satisfaction. Multilamellar vesicles ropivacaine, MVR, is being developed to sustain the release of ropivacaine in situ while maintaining the local concentration of ropivacaine within the therapeutic window. Methods: These studies summarized the processes of MVR formulation development and the evaluation of its releasing profile in vitro and the pharmacokinetics and anesthetic effect in vivo. Results: The MVR demonstrates a sustained-release profile in an in vitro serum environment model after 24 hrs of incubation which translates in the in vivo rat pharmacokinetic profile of ropivacaine as a prolonged half-life that is 10-fold longer in duration than plain ropivacaine solution. The anesthetic effect of single-dose MVR is apparent by providing a prolonged analgesia effect compared to plain ropivacaine solution in an in vivo guinea pig pin-prick wheal model after a single intracutaneous injection. From a safety evaluation, MVR is well tolerated after a subcutaneously injection at a dose level of 20 mg/kg in rats, with no observable changes in clinical observation, body weight, organ weight, hematology and serum chemistry analysis. Conclusion: These results suggest that single administration of MVR is a promising candidate in postoperative pain management.