Patent attributes
A long-lasting, controlled-release local anesthetic liposome preparation is produced by: providing a liposome composition, which is obtained by mixing, in a water-miscible organic solvent, a first aqueous phase solution with a water-miscible organic solution, in which a phospholipid and cholesterol are contained at a defined total concentration, at a defined ratio by volume thereby obtaining an emulsion wherein a total concentration of the phospholipid and cholesterol in the mixed phase is at 15 w/v % to 50 w/v %, followed by subjecting the emulsion to external solution exchange with a second aqueous phase solution to obtain a liposome composition wherein an ion gradient is formed between an internal-region aqueous phase of a liposome membrane made of the first aqueous phase solution and an external-region aqueous phase of the liposome membrane made of the second aqueous phase solution; and encapsulating a local anesthetic in the internal-region aqueous phase according to a remote loading method.
