Patent ID: 9724300
Date: 2017-08-08
CPC Classifications: A61K,A61P

Claim:
1. A long-lasting, controlled-release local anesthetic liposome preparation, which is prepared by: providing a liposome composition 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 total concentration of 100 w/v % to 200 w/v %, at a ratio by volume of 3/1 to 12/1 in terms of the unit volume to the water-miscible organic solution 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 of empty liposomes formed from the phospholipid and cholesterol, wherein the internal-region aqueous phase is in a multilayer membrane having a layered structure of at least 12 layers.