Method of making particles for use in a pharmaceutical composition
The invention relates to a method for making composite active particles for use in a pharmaceutical composition for pulmonary administration, the method comprising a milling step in which particles of active material are milled in the presence of particles of an additive material which is suitable for the promotion of the dispersal of the composite active particles upon actuation of an inhaler. The invention also relates to compositions for inhalation prepared by the method.
1. A method for making composite active particles for use in a pharmaceutical composition for pulmonary administration, the method comprising a milling step in which particles of active material are milled in the presence of particles of an additive material so as to ensure a sufficient break-up of agglomerates of both active material and additive material, dispersal and even distribution of the additive material over the active material, and so that the particles of additive material become fused to the surface of the particles of active material; wherein the additive material is suitable for the promotion of the dispersal of the composite active particles upon actuation of an inhaler, wherein the milling step comprises:
(a) passing a mixture of particles of additive material and particles of active material, in a fluid, through a constriction under pressure;
(b) compressing a mixture of particles of additive material and particles of active material in a gap of predetermined width; or
(c) jet milling particles of additive material with particles of active material to provide a break-up of agglomerates of both active material and additive material, dispersal and distribution of the additive material over the active material, such that the particles of additive material become fused to the surface of the particles of active material, wherein the additive material is suitable for the promotion of the dispersal of the composite active particles upon actuation of an inhaler.
2. A method as claimed in claim 1 , in which the mass median aerodynamic diameter (MMAD) of the particles of active material is reduced by at least 10% during the milling step.
3. A method as claimed in claim 1 , in which the mass median aerodynamic diameter (MMAD) of the particles of additive material is reduced by at least 10% during the milling step.
4. A method as claimed in claim 1 , in which, after the milling step, the mass median aerodynamic diameter of the composite active particles is not more than 10 μm.
5. A method as claimed in claim 1 , which also comprises, after the milling step, a processing step in which the degree of aggregation of the composite active particles is changed.
6. A method as claimed in claim 5 , in which the processing step is a deagglomeration step.
7. A method as claimed in claim 1 , wherein after the milling step, liquid is added, followed by a drying step in which the mixture of the composite active particles and the liquid is dried to remove the liquid.
8. A method as claimed in claim 7 , in which the drying step is a spray drying step.
9. A method as claimed in claim 7 , in which in the drying step the liquid is evaporated.
10. A method as claimed in claim 7 , in which the drying step is a freeze drying step.
11. A method as claimed in claim 1 , in which the additive material comprises an amino acid.
12. A method as claimed in claim 1 , in which the additive material comprises a phospholipid.
13. A method as claimed in claim 1 , in which the additive material comprises a metal stearate.
14. A method according to claim 1 in which the milling step involves compressing a mixture of the active particles and additive particles in a gap not more than 10 mm wide.
15. A method as claimed in claim 1 , in which the milling step is performed using a hybridiser method.
16. Composite active particles for use in a pharmaceutical composition as made by the method of claim 1 .
17. Composite particles as claimed in claim 16 in which the additive particles form a coating on the surfaces of the particles of active material.
18. Composite active particles as claimed in claim 17 in which the coating is a discontinuous coating.
19. Composite active particles as claimed in claim 17 in which the coating is not more than 1 μm thick.
20. A pharmaceutical composition comprising composite active particles as claimed in claim 16 , which is a dry powder and is suitable for use in a dry powder inhaler.
21. A pharmaceutical composition comprising composite active particles as made by a method according to claim 1 .
22. A pharmaceutical composition as claimed in claim 21 , which further comprises a propellant and is suitable for use in a pressurized metered dose inhaler.