Injectable antibiotic formulations and their methods of use

1. A composition comprising penethamate (PNT) or a pharmaceutical equivalent thereof; and triacetin.

2. A composition as claimed in claim 1 wherein the viscosity of the composition is less than 3000 mPa·s at a temperature of 20° C. and a shear rate of 1/s, wherein the viscosity is measured with a cup cylinder method.

3. A composition as claimed in claim 1 wherein the composition comprises 55% w/v or less of penethamate (PNT) or a pharmaceutical equivalent thereof.

4. A composition as claimed in claim 3 wherein the composition comprises 15-55% w/v of penethamate (PNT) or a pharmaceutical equivalent thereof.

5. A composition as claimed in claim 4 wherein the composition comprises 20-35% w/v of penethamate (PNT) or a pharmaceutical equivalent thereof.

6. A composition as claimed in claim 1 further comprising at least one anti-caking agent.

7. A composition as claimed in claim 6 wherein the anti-caking agent is non-thickening.

8. A composition as claimed in claim 1 wherein the composition is in liquid form.

9. A composition as claimed in claim 1 comprising penethamate (PNT) having a particle diameter d 50 of 8-30 microns.

10. A composition as claimed in claim 1 further comprising a surfactant.

11. A composition as claimed in claim 10 wherein the surfactant is polysorbate 80.

12. A composition as claimed in claim 1 further comprising a preservative.

13. A composition as claimed in claim 12 wherein the preservative is benzyl alcohol.

14. A composition as claimed in claim 1 further comprising an emulsifier or dispersing agent.

15. A composition as claimed in claim 14 wherein the emulsifier or dispersing agent is phospholipon H90.

16. A pre-filled syringe comprising a composition as claimed in claim 1 .

17. A pre-filled syringe as claimed in claim 16 comprising 5 g of penethamate.

18. A method for the treatment of a microbial infection comprising administering to an animal in need thereof a composition as claimed in claim 1 by intramuscular or subcutaneous injection.

19. A method as claimed in claim 18 wherein the microbial infection is pre-clinical or clinical mastitis.

20. A method as claimed in claim 18 wherein the method of treatment comprises a dosage regime of 5 g penethamate per day repeated for approximately three days.

21. A method of manufacturing the composition as claimed in claim 10 comprising:

a) mixing triacetin and a surfactant in a container to form a homogenous mixture, and

b) dispersing the penethamate (PNT) or a pharmaceutical equivalent thereof in the triacetin mixture.

22. A method of manufacturing as claimed in claim 21 further comprising adding a preservative to the triacetin in step a).

23. A method of manufacturing as claimed in claim 21 wherein high shear dispersion equipment is used in step b).