A method of preparing a pharmaceutical composition is described, comprising 1) atomizing a liquid formulation of a therapeutic agent to produce an atomized formulation; 2) freezing said atomized formulation to form solid particles; and 3) drying said solid particles at about atmospheric pressure to produce a powder, wherein said drying is performed in the presence of vibration, internals, mechanical stirring, or a combination thereof. Another method is described, comprising 1) atomizing a liquid formulation of a therapeutic agent to produce an atomized formulation; 2) freezing said atomized formulation to form solid particles; and 3) drying said solid particles to produce a powder; wherein the atomized formulation comprises droplets having an average mean diameter of between about 35μ and about 300μ, and/or the powder comprises dried particles having an average mean diameter of between about 35μ and about 300μ. Compositions made by the above methods, and methods of using the compositions, are also described.