An investigation into the influence of a co-solvent system on the physiochemical properties of spray dried guaifenesin

Guaifenesin, a widely used expectorant, provides symptomatic relief for chest congestion and coughs associated with bronchitis, common colds, and other respiratory diseases. Pulmonary delivery via inhalation is advantageous for treating lung-related conditions, including asthma, chronic obstructive pulmonary disease (COPD), and various pulmonary infections. Spray drying, has superior particle engineering capabilities and is a well-known technique for engineering particles suitable for pulmonary delivery. This study demonstrates a route for effective spray drying of guaifenesin by exploiting a co-solvent system of methanol and water. It evaluates the interplay of co-solvent ratios, atomisation gas flow rates and the addition of an excipient on yield, particle size and density, with a view to engineering particles suitable for pulmonary delivery. Results show that particles with sizes below 5 µm (D₅₀) and densities of 1.44 g.cm⁻³ are readily attainable at high atomisation gas flow rates in all co-solvent ratios. At lower atomisation gas flow rates, the co-solvent ratio is the predominant factor influencing particle size.