Claims for Patent: 8,048,451

Summary for Patent: 8,048,451

Title:	Pharmaceutical compositions for inhalation
Abstract:	The invention provides microparticles for use in a pharmaceutical composition for pulmonary administration, each microparticle comprising a particle of an active substance having, on its surface, particles of a hydrophobic material suitable for delaying the dissolution of the active substance. The invention also provides a method for making the microparticles.
Inventor(s):	Staniforth; John Nicholas (Bath, GB), Harris; Haggis (Bristol, GB), Morton; David Alexander Vodden (Bath, GB), Bannister; Robin (Essex, GB)
Assignee:	Vectura Limited (Wiltshire, GB)
Application Number:	10/433,185
Patent Claims:	1. A method of preparing microparticles for use in a pharmaceutical composition for pulmonary administration, comprising particles of active substance having, on their surfaces, particles of a hydrophobic material suitable for delaying the dissolution of the active substance, the method comprising milling particles of the active substance, wherein particles of hydrophobic material are present during said milling, so as to ensure a sufficient break-up of agglomerates of both active and hydrophobic material, dispersal and even distribution of the hydrophobic material over the active material, so that the particles of hydrophobic material become fused to the surface of the particles of active material, said microparticles exhibiting delayed dissolution as compared to the particles of the active substance, wherein the milling is dry milling, and wherein the milling comprises: (a) passing a mixture of particles of active material and particles of hydrophobic material in a fluid, through a constriction under pressure; (b) compressing a mixture of particles of active material and particles of hydrophobic material in a gap of predetermined width; or (c) jet milling particles of active material with particles of hydrophobic material. 2. A method of pulmonary administration of an active substance comprising a step of administering microparticles prepared according to the method of claim 1 to a person in need thereof. 3. A method according to claim 1, wherein the hydrophobic material comprises a C.sub.10 to C.sub.22 carboxylic acid, which may be linear or branched, saturated or unsaturated, or an ester, amide or a salt thereof. 4. A method according to claim 3, wherein the hydrophobic material comprises magnesium stearate. 5. A method according to claim 1, wherein the hydrophobic material comprises a phospholipid. 6. A method according to claim 1, wherein the microparticles comprise not more than 90% of the hydrophobic material based on the total weight of the microparticles. 7. A method according to claim 1, wherein the microparticles have a mass median aerodynamic diameter of not more than 10 .mu.m. 8. A method according to claim 1, wherein the microparticles are agglomerated. 9. A method as claimed in claim 1, wherein the microparticles have at least a partial coating of a film-forming material. 10. A method as claimed in claim 1, in which the particles of hydrophobic material are present as a coating on the surface of the particles of active substance. 11. A method as claimed in claim 10, in which the coating is a discontinuous coating. 12. A method of preparing microparticles for use in a pharmaceutical composition for pulmonary administration, comprising particles of active substance having, on their surfaces, particles of a hydrophobic material suitable for delaying the dissolution of the active substance, the method comprising milling particles of the active substance, wherein particles of hydrophobic material are present during said milling, so as to ensure a sufficient break-up of agglomerates of both active and hydrophobic material, dispersal and even distribution of the hydrophobic material over the active material, so that the particles of hydrophobic material become fused to the surface of the particles of active material, said microparticles exhibiting delayed dissolution as compared to the particles of the active substance, wherein the milling is dry milling, and wherein the milling comprises: (a) passing a mixture of particles of active material and particles of hydrophobic material in a fluid, through a constriction under pressure; (b) compressing a mixture of particles of active material and particles of hydrophobic material in a gap of predetermined width; or (c) jet milling particles of active material with particles of hydrophobic material, wherein the microparticles do not comprise an effective amount of an antimuscarinic agent. 13. Microparticles for use in a pharmaceutical composition, as made by the method of claim 1 or claim 12. 14. Microparticles as claimed in claim 13, wherein the hydrophobic material forms at least a partial coating on the surface of the active material. 15. Microparticles as claimed in claim 14, wherein the coating is a discontinuous coating. 16. A method of delaying a dissolution rate of an active substance of a pharmaceutical composition for pulmonary administration; the method comprising milling particles of an active substance, wherein particles of hydrophobic material are present during said milling, so as to ensure a sufficient break-up of agglomerates of both active and hydrophobic material, dispersal and even distribution of the hydrophobic material over the active material, so that the particles of hydrophobic material become fused to the surface of the particles of active material and administering the pharmaceutical composition to the lung of the patient, wherein the milling is dry milling, and wherein the milling comprises: (a) passing a mixture of particles of active material and particles of hydrophobic material in a fluid, through a constriction under pressure; (b) compressing a mixture of particles of active material and particles of hydrophobic material in a gap of predetermined width; or (c) jet milling particles of active material with particles of hydrophobic material. 17. The method as claimed in claim 16 in which the dissolution rate is reduced by at least 20%. 18. A method as claimed in claim 16, wherein, upon inhalation of the microparticles, the active substance exerts its pharmaceutical effect over a period greater than the period over which the active substance exerts its pharmaceutical effect when inhaled alone. 19. The method of claim 18, wherein the active substance exerts its effect for a period greater than 12 hours.