Details for Patent: 7,718,163

Title:	Carrier particles for use in dry powder inhalers
Abstract:	A powder for use in a dry powder inhaler includes active particles and carrier particles for carrying the active particles. The powder further includes additive material (4) on the surfaces of the carrier particles to promote the release of the active particles from the carrier particles on actuation of the inhaler. The powder is such that the active particles are not liable to be release from the carrier particles before actuation of the inhaler. The inclusion of additive material (4) in the powder has been found to give an increased respirable fraction of the active material.
Inventor(s):	Staniforth; John Nicholas (Bath, GB)
Assignee:	Vectura Limited (01696917) (Wiltshire, GB)
Filing Date:	Aug 11, 2005
Application Number:	11/202,741
Claims:	1. A method of preparing a powder for use in a dry powder inhaler, the powder comprising active particles, carrier particles for carrying active particles, and particles of additive material; said method comprising: (a) mixing carrier particles of a size suitable for use in dry powder inhalers with particles of additive material, so that the particles of additive material become attached to the surfaces of the carrier particles; and then (b) mixing active particles with the carrier particles and additive material from step (a), so that the active particles adhere to the surfaces of the carrier particles and/or additive material; wherein the additive material is a physiologically acceptable material and promotes the release of the active particles from the carrier particles on actuation of the inhaler, wherein some of the particles of additive material may act as carriers of active particles and may be separate from or may separate from the surfaces of the carrier particles with active particles attached to their surfaces, and wherein the powder has a post-vibration homogeneity measured as a percentage coefficient of variation of less than about 5%. 2. A method as claimed in claim 1, wherein the method further includes the step of selecting from a sample of carrier particles an advantageous range of size of carrier particles prior to the mixing step (a). 3. A method as claimed in claim 1, wherein the method further includes the step of selecting from a sample of additive particles an advantageous range of size of particles of additive material prior to the mixing step (a). 4. A method as claimed in claim 1, wherein the additive material is added in the form of a suspension. 5. A method as claimed in claim 1, wherein the additive material includes one or more water soluble substances. 6. A method as claimed in claim 1, wherein the additive material and the carrier particles are mixed for between 0.1 hours and 0.5 hours. 7. A method as claimed in claim 1, wherein the carrier particles are mixed with the additive material using a tumbling blender. 8. A method as claimed in claim 1, wherein the method further includes the step of treating the carrier particles to dislodge small grains from the surfaces of the carrier particles, without substantially changing the size of the carrier particles during the treatment. 9. A method as claimed in claim 8, wherein the mixing step (a) is prior to the treatment step. 10. A method as claimed in claim 8,wherein many of the small grains become reattached to the surfaces of the carrier particles. 11. A method as claimed in claim 8, wherein the treatment is a milling step. 12. A method as claimed in claim 11, wherein the milling step is performed in a ball mill. 13. A method as claimed in claim 12, wherein the carrier particles are milled using plastic balls. 14. A method as claimed in claim 8, wherein the treatment step is carried out in a recirculated low fluid energy mill. 15. A method as claimed in claim 11, wherein the carrier particles are milled for between about 0.25 hours and 6 hours. 16. A method as claimed in claim 1, wherein the powder includes not more than 10% by weight of additive material based on the weight of the powder. 17. A method as claimed in claim 16, wherein the powder includes not more than 5% by weight of additive material based on the weight of the powder. 18. A method as claimed in claim 17, wherein the powder includes not more than 2% by weight of additive material based on the weight of the powder. 19. A method as claimed in claim 1, wherein the particles of additive material have a mass median diameter of not more than 10.mu.m. 20. A method as claimed in claim 1, wherein the particles of additive material have a surface of at least 5 m.sup.2g.sup.-1. 21. A method as claimed in claim 1, wherein the carrier particles are comprised of one or more crystalline sugars. 22. A method as claimed in claim 21, wherein the carrier particles are particles of lactose. 23. A method as claimed in claim 1, wherein substantially all (by weight) of the carrier particles have a diameter which lies between 20 .mu.m and 1000 .mu.m. 24. A method as claimed in claim 1, wherein the additive material consists of surface active material. 25. A method as claimed in claim 1, wherein the additive material includes one or more compounds selected from amino acids and derivatives thereof, and peptides and polypeptides having a molecular weight from 0.25 to 1000 KDa, and derivatives thereof. 26. A method as claimed in claim 25, wherein the additive material includes an amino acid. 27. A method as claimed in claim 26, wherein the additive material includes or consists of leucine. 28. A method as claimed in claim 1, wherein the additive material includes one or more water soluble materials. 29. A method as claimed in claim 1, wherein the additive material comprises a phospholipid or a derivative thereof. 30. A method as claimed in claim 29, wherein the additive material comprises lecithin. 31. A method as claimed in claim 30, wherein the additive material comprises soya lecithin. 32. A method as claimed in claim 1, wherein the additive material comprises palmitic acid, stearic acid, erucic acid, behenic acid, magnesium stearate, sodium stearyl fumarate, sodium stearyl lactylate, a phosphatidylcholine, a phosphatidylglycerol, a liposomal formulation, lauric acid or a lauric acid salt, or a triglyceride. 33. A method as claimed in claim 1, wherein the additive material comprises magnesium stearate in an amount that forms less than 1.5% by weight of the powder. 34. A method as claimed in claim 1, wherein the additive material includes a plurality of surface active materials. 35. A method as claimed in claim 1, wherein the additive material is an anti-adherent material. 36. A method as claimed in claim 1, wherein the additive material is an anti-friction agent. 37. A method as claimed in claim 1, wherein the additive material includes dipolar ions. 38. A method as claimed in claim 37, wherein the additive material consists of zwitterions. 39. A method as claimed in claim 1, wherein the powder consists of not less than 0.1% by weight of additive particles based on the weight of the carrier particles. 40. A method as claimed in claim 1, wherein the particles of additive material form a discontinuous covering on the surfaces of the carrier particles. 41. A method as claimed in claim 40, wherein the particles of additive material, whilst forming a discontinuous covering on the surfaces of the carrier particles, saturate the surfaces of the carrier particles. 42. A method as claimed in claim 1, wherein the mass median diameter of the active particles is not more than 10.mu.m. 43. A method as claimed in claim 1, wherein the active particles include a .beta..sub.2-agonist. 44. A method as claimed in claim 43, wherein the active particles include salbutamol, a salt of salbutamol, salmeterol and/or a salt of salmeterol. 45. A method as claimed in claim 1, wherein the active particles include beclomethasone dipropionate.