Liposomal bupivacaine

Local anesthetics are encapsulated into liposomes in order to prolong their effective duration without increasing their toxicity. In this study we aimed to prepare different forms of multilamellar liposomal bupivacaine to evaluate controlled release properties for bupivacaine in artificial cerebrospinal fluid (CSF). Primarily, bupivacaine HCl, bupivacaine base, cholesterol, dipalmitoyl phosphatidyl choline and methanole were distilated with vacuum in rotavapor device. They were kept in ultrasound bath to achive homogenic distribution to get bupivacaine base with liposomal bupivacaine base and bupivacaine HCl with liposomal bupivacaine HCl. Solutions of bupivacaine base with liposomal bupivacaine base and bupivacaine HCl with liposomal bupivacaine HCl were centrifuged to get liposomal bupivacaine base and liposomal bupivacaine HCl. Artificial CSF buffered solution was prepared. The first experiment was carried out with using bupivacaine base with liposomal bupivacaine base and bupivacaine HCl with liposomal bupivacaine HCl. Bupivacaine base with liposomal bupivacaine base, bupivacaine HCl with liposomal bupivacaine HCl and bupivacaine HCl were put in franz diffusion cell. The solutions were kept in hot water bath for 24 hours. The samples were taken in the first half, 1, 3, 6, 12 and 24th hours (first experiment). Liposomal bupivacaine base and liposomal bupivacaine HCl were put in franz diffusion cell. The solutions were kept in hot water bath for 24 hours. The samples were taken in the first half, 1, 3, 6, 12 and 24th hours (second experiment). Calibration graphics were obtained for bupivacaine and bupivacaine HCl. Fifty-four sample obtained from the first experiment and 36 samples obtained from the second study were analyzed with HPLC and UPLC, respectively and the chromatographies were obtained. Consequently multilamellar liposomal bupivacaine showed slow release in artificial CSF compared to bupivacaine HCl. The liposomal formulations of the bupivacaine HCl and bupivacaine base demonstrated different releasing rate patterns.Key Words: Liposome, bupivacaine, CSF