A method of filling a capsule, the method comprising the steps of: creating a low pressure vacuum within the dosator; positioning the dosator in a bowl filled with powder and drawing the powder into the dosator chamber; maintaining the powder in the dosator chamber with the low pressure vacuum to form a slug of powder having a predetermined bulk density; and expelling the slug of powder into a capsule; wherein the dry powder has 40% or more particles that have an aerodynamic diameter of less than 5.6 μm (fine particle fraction) and the mass median geometric diameter of the particles is between 5 μm and 18 μm or between 8 μm and 18 μm; wherein the dosator comprises: a tube which tapers from the top of the dosator to the bottom of the dosator having an axial passage therein forming an elongate cavity; a stationary plunger disposed within the cavity; a removable mesh screen having a mesh size that is smaller than the mass median geometric diameter (D 50) of the dry powder disposed between the stationary plunger and the bottom of the dosator; a dosator chamber defined between the mesh screen and the bottom of the dosator of a predetermined height, for receiving powder from a powder source and holding the powder until it is expelled into the capsule; at least one vacuum pump operably linked to the dosator and capable of drawing dry powder into the dosator chamber from the bowl; and compacting the powder into a slug of powder having a predetermined bulk density prior to expelling the slug of powder into a capsule; and at least one source of positive pressure operably linked to the dosator and capable of providing positive pressure to expel the powder slug from the dosator, wherein, a) when the mass median geometric diameter of the powder particles is between 5 μm and 18 μm, the mesh screen is a 2 micron mesh, or b) when the mass median geometric diameter of the powder particles is between 8 μm and 18 μm, the mesh screen is a 2 or 5 micron mesh. creating a low pressure vacuum within the dosator; positioning the dosator in a bowl filled with powder and drawing the powder into the dosator chamber; maintaining the powder in the dosator chamber with the low pressure vacuum to form a slug of powder having a predetermined bulk density; and expelling the slug of powder into a capsule; wherein the dry powder has 40% or more particles that have an aerodynamic diameter of less than 5.6 μm (fine particle fraction) and the mass median geometric diameter of the particles is between 5 μm and 18 μm or between 8 μm and 18 μm; wherein the dosator comprises: a tube which tapers from the top of the dosator to the bottom of the dosator having an axial passage therein forming an elongate cavity; a stationary plunger disposed within the cavity; a removable mesh screen having a mesh size that is smaller than the mass median geometric diameter (D 50) of the dry powder disposed between the stationary plunger and the bottom of the dosator; a dosator chamber defined between the mesh screen and the bottom of the dosator of a predetermined height, for receiving powder from a powder source and holding the powder until it is expelled into the capsule; at least one vacuum pump operably linked to the dosator and capable of drawing dry powder into the dosator chamber from the bowl; and compacting the powder into a slug of powder having a predetermined bulk density prior to expelling the slug of powder into a capsule; and at least one source of positive pressure operably linked to the dosator and capable of providing positive pressure to expel the powder slug from the dosator, wherein, a) when the mass median geometric diameter of the powder particles is between 5 μm and 18 μm, the mesh screen is a 2 micron mesh, or b) when the mass median geometric diameter of the powder particles is between 8 μm and 18 μm, the mesh screen is a 2 or 5 micron mesh. a tube which tapers from the top of the dosator to the bottom of the dosator having an axial passage therein forming an elongate cavity; a stationary plunger disposed within the cavity; a removable mesh screen having a mesh size that is smaller than the mass median geometric diameter (D 50) of the dry powder disposed between the stationary plunger and the bottom of the dosator; a dosator chamber defined between the mesh screen and the bottom of the dosator of a predetermined height, for receiving powder from a powder source and holding the powder until it is expelled into the capsule; at least one vacuum pump operably linked to the dosator and capable of drawing dry powder into the dosator chamber from the bowl; and compacting the powder into a slug of powder having a predetermined bulk density prior to expelling the slug of powder into a capsule; and at least one source of positive pressure operably linked to the dosator and capable of providing positive pressure to expel the powder slug from the dosator, wherein, a) when the mass median geometric diameter of the powder particles is between 5 μm and 18 μm, the mesh screen is a 2 micron mesh, or b) when the mass median geometric diameter of the powder particles is between 8 μm and 18 μm, the mesh screen is a 2 or 5 micron mesh. a) when the mass median geometric diameter of the powder particles is between 5 μm and 18 μm, the mesh screen is a 2 micron mesh, or b) when the mass median geometric diameter of the powder particles is between 8 μm and 18 μm, the mesh screen is a 2 or 5 micron mesh.