Spray Drying Enhances Solubility And Bioavailability Of Poorly Soluble Drugs

In spray drying, a liquid feed (solution or suspension) is sprayed into a hot gas stream with the intent to isolate products in a solid form state as well-defined powder. By application of spraying, the liquid evolves as small droplets with precisely defined volume(s). These droplets are then transported with the gas flow along a drying chamber (referred to as ‘flight time’). During the flight time, the solvent evaporates from the droplets until only residual solids remain. The hot gas becomes saturated with solvent vapor during this process. The powder is then separated from the drying gas stream and collected. Evaporating solvent from the droplets consumes energy which is delivered by the hot gas around the droplet, so that the droplet stays cold and the gas becomes cooled. Due to these physical principles, the product stays at a well-defined temperature range during the drying process even though the gas temperature at the inlet is much higher. Temperature is only applied for a short period of the flight time to the product allowing spray drying to run as a gentle continuous drying operation, with minimal thermal stress on a product.