Patent ID: 8182835

Claim:
A multivesicular liposome formulation comprising bupivacaine phosphate made by a process comprising: a) preparing a first aqueous component comprising at least one acid in sufficient quantity to solubilize bupivacaine or a salt thereof, said acid being phosphoric acid; b) preparing a lipid component comprising at least one organic solvent, at least one amphipathic lipid, and at least one neutral lipid lacking a hydrophilic head group; c) mixing said first aqueous component and said lipid component to form a water-in-oil emulsion, wherein at least one component comprises bupivacaine or a salt thereof; d) mixing said water-in-oil emulsion with a second aqueous component to form solvent spherules; and e) removing the organic solvent from the solvent spherules to form multivesicular liposomes.