Preparation of levobupivacaine hydrochloride sustained-release in-situ gel injection and its pharmacokinetic and pharmacodynamic studies in animals

The purpose of this study was to develop a novel phospholipidas-based in-situ gel sustained-release formulation of levobupivacaine hydrochloride injection. Appropriate formulation was screened based on the factors such as phospholipid type, ratio of phospholipid to ethanol, ratio of water to phospholipid-ethanol mixture, which indicated typical in-situ gel profiles. Pharmacokinetic study using beagles showed that there were delayed tmax and prolonged t_1/2 in levobupivacaine plasma-time profile after administration of the phospholipidas-based in-situ gel formulation if compared to commercially available conventional levobupivacaine hydrochloride injection. Pharmacodynamic studies conducted on guinea-pig demonstrated that it maintained 48-72 hr regional anesthesia, much longer than that of the anesthesia in the group receiving conventional injection. Hence, this novel in-situ gel intended for injection is worthy of development.