Lipid depot formulations

26) A method of delivery of a bioactive agent to a human or non-human animal (preferably mammalian) body, this method comprising administering a pre-formulation comprising a non-liquid crystalline, low viscosity mixture of:

• a) at least one neutral diacyl lipid and/or at least one tocopherol;
• b) at least one phospholipid;
• c) at least one biocompatible, oxygen containing, low viscosity organic solvent;
• and at least one bioactive agent is dissolved or dispersed in the low viscosity mixture, whereby to form at least one liquid crystalline phase structure upon contact with an aqueous fluid in vivo following administration.

29) A method for the preparation of a liquid crystalline composition comprising exposing a pre-formulation comprising a non-liquid crystalline, low viscosity mixture of:

• a) at least one neutral diacyl lipid and/or at least one tocopherol;
• b) at least one phospholipid;
• c) at least one biocompatible, oxygen containing, low viscosity organic solvent;
• and at least one bioactive agent dissolved or dispersed in the low viscosity mixture, to an aqueous fluid in vivo.

31) A process for the formation of a pre-formulation suitable for the administration of a bioactive agent to a (preferably mammalian) subject, said process comprising forming a non-liquid crystalline, low viscosity mixture of

• a) at least one neutral diacyl lipid and/or at least one tocopherol;
• b) at least one phospholipid;
• c) at least one biocompatible, oxygen containing low viscosity, organic solvent;
• and dissolving or dispersing at least one bioactive agent in the low viscosity mixture, or in at least one of components a, b or c prior to forming the low viscosity mixture.

33) The use of a non-liquid crystalline, low viscosity mixture of:

• a) at least one neutral diacyl lipid and/or at least one tocopherol;
• b) at least one phospholipid;
• c) at least one biocompatible, oxygen containing, low viscosity organic solvent;
• wherein at least one bioactive agent is dissolved or dispersed in the low viscosity mixture in the manufacture of a pre-formulation for use in the sustained administration of said active agent, wherein said pre-formulation is capable of forming at least one liquid crystalline phase structure upon contact with an aqueous fluid.