Many new chemical entities (NCE) display poor aqueous solubility and hence low dissolution rates. This reduces the bioavailability of the API
, sometimes to the point of failing to cause a therapeutic effect.
With spray drying it is possible to co-precipitate an API with a polymer in a stable amorphous solid dispersion, thereby greatly improving the dissolution rate. Specifically it is the unparalleled drying rate that allows the API to be captured in amorphous form. Such powders are often referred to as “Spray Dried Solid Dispersion” (SDD).
Alternative techniques for the improvement of the dissolution rate are the creation of nano-particles or micronized API crystals. However, the very small particles are difficult to handle e.g. ensuring homogeneous blending – and they often re-crystallise or form strong agglomerates. Spray drying an appropriate feed in which the nano or micronized particles are suspended will give a stable, uniform and easy to handle powder that will reconstitute into the original particle size distribution upon dissolution in the body.