Liquid depot formulations

1. A non-liquid crystalline formulation precursor for the in vivo generation of a liquid crystalline lipid composition for the controlled release of at least one bioactive agent following parenteral administration, said formulation precursor comprising:

i) a low-viscosity, non-liquid crystalline mixture having a viscosity of 1 to 1000 mPas at 20° C. and comprising:

a) a minimum of 18 wt. % of a component consisting of at least one diacyl glycerol or at least one diacyl glycerol and at least one tocopherol;

b) at least one phosphatidylcholine; and

c) at least one biocompatible solvent comprising ethanol;

ii) at least one bioactive agent dissolved or dispersed in the low viscosity mixture;

wherein the formulation precursor forms at least one liquid crystalline phase structure in vivo upon contact with an aqueous fluid.

2. A non-liquid crystalline formulation precursor for the in vivo generation of a liquid crystalline lipid composition for the controlled release of at least one bioactive agent following parenteral administration, said formulation comprising:

i) a low-viscosity, non-liquid crystalline mixture having a viscosity of 1 to 1000 mPas at 20° C. and comprising:

a) a minimum of 18 wt. % of a component consisting of at least one tocopherol and at least one diacyl glycerol;

b) at least one phosphatidylcholine; and

c) at least one biocompatible, oxygen containing, low viscosity organic solvent;

ii) at least one bioactive agent dissolved or dispersed in the low viscosity mixture;

wherein the formulation precursor forms at least one liquid crystalline phase structure in vivo upon contact with an aqueous fluid.

3. The formulation precursor as claimed in claim 1 wherein component a) consists essentially of diacyl glycerols.

4. The formulation precursor as claimed in claim 3 wherein said diacyl glycerols comprise glycerol dioleate.

5. The formulation precursor as claimed in claim 1 wherein component a) consists essentially of a mixture of glycerol dioleate (GDO) and tocopherol.

6. The formulation precursor as claimed in claim 1 having a molecular solution, L 2 and/or L 3 phase structure.

7. The formulation precursor as claimed in claim 1 having a ratio of a) to b) of between 95:5 and 5:95 by weight.

8. The formulation precursor as claimed in claim 1 having 0.5 to 50% component c) by weight of components a)+b)+c).

9. The formulation precursor as claimed in claim 1 additionally comprising up to 10% by weight of a)+b) of a charged amphiphile.

10. The formulation precursor as claimed in claim 1 wherein said active agent is selected from drugs, antigens, nutrients, cosmetics, fragrances, flavourings, diagnostic agents, vitamins, dietary supplements and mixtures thereof.

11. The formulation precursor as claimed in claim 10 wherein said drug is selected from hydrophilic small molecule drugs, lipophilic small molecule drugs, amphiphilic small molecule drugs, peptides, proteins, oligonucleotides and mixtures thereof.

12. The formulation precursor as claimed in claim 10 wherein said drug is selected from somatostatin related peptides, interferons, glucagon-like peptides 1 and 2, GnRH agonists, GnRH antagonists, bisphosphonates, chlorhexidine and mixtures thereof.

13. The formulation precursor as claimed in claim 1 which is administrable by injection.

14. An injectable formulation precursor as claimed in claim 1 which forms a depot providing continuous release of active agent for at least two weeks, wherein said active agent comprises at least one selected from

i. octreotide

ii. human growth hormone

iii. interferon alpha

iv. leuprolide.

15. An injectable formulation precursor as claimed in claim 1 which forms a depot providing continuous release of active agent for at least two weeks, wherein said active agent comprises at least one selected from

i. risperidone

ii. olanzapine

iii. testosterone undecanoate.

16. A method of delivery of a bioactive agent to a human or non-human animal (preferably mammalian) body, this method comprising administering the formulation precursor as claimed in claim 1 whereby to form at least one liquid crystalline phase structure upon contact with an aqueous fluid in vivo following administration.

17. The method as claimed in claim 16 wherein said formulation precursor is administered by a method selected from subcutaneous injection, intramuscular injection, intra-cavity injection through tissue, intra-cavity injection into an open cavity without tissue penetration.

18. A method for the preparation of a liquid crystalline composition comprising exposing the formulation precursor as claimed in claim 1 to an aqueous fluid in vivo.

19. A process for the formation of a formulation precursor for the administration of a bioactive agent to a mammalian subject, said process comprising:

i) forming a non-liquid crystalline, low viscosity mixture having a viscosity of 1 to 1000 mPas at 20° C. and comprising:

a) a minimum of 18 wt. % of at least one neutral diacyl glycerol or at least one neutral diacyl glycerol and at least one tocopherol;

b) at least one phosphatidylcholine;

c) at least one biocompatible solvent having a viscosity of no more than 15 mPas at 20° C. comprising ethanol; and

ii) 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.

20. A process for the formation of a formulation precursor for the administration of a bioactive agent to a mammalian subject, said process comprising:

i) forming a non-liquid crystalline, low viscosity mixture having a viscosity of 1 to 1000 mPas at 20° C. and comprising:

a) a minimum of 18 wt. % of at least one tocopherol and least one diacyl glycerol;

b) at least one phosphatidylcholine;

c) at least one biocompatible, oxygen containing, low viscosity organic solvent; and

ii) 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.

21. A process as claimed in claim 19 wherein said formulation precursor is the formulation precursor as claimed in claim 1 .

22. A method of treatment or prophylaxis of a human or non human animal subject comprising parenteral administration of the formulation precursor as claimed in claim 1 .

23. The method of claim 22 for the treatment of a condition selected from bacterial infection, fungal infection, skin soreness, eye conditions, genital soreness, infections and conditions for the finger and/or toe nails, travel sickness, addiction including nicotine addiction, periodontal infection, conjunctivitis, glaucoma and hormone deficiency or imbalance.

24. The method of claim 22 for prophylaxis against at least one condition selected from infection during surgery, infection during implantation, sunburn, infection at the site of burns, cuts or abrasions, oral infections, genital infections and infections resulting from activities resulting in exposure to infective agents.