Development and Characterization of Andrographolide Microparticles via Spray Drying: An Aqueous-Based...

Andrographolide-loaded microparticles with an aqueous-based carrier system were developed with the aim of pulmonary drug delivery. Five formulations of andrographolide (0.6-5.8% w/w) loaded on mixed-polymer carriers containing chitosan (CHS), hydroxyethyl cellulose (HEC), Poloxamer 188, and PEG 20,000, with various ratios were produced under various spray-drying parameters: solution viscosity (5-20 cP), atomization air pressure (0.8-1.5 bar) and solution feed rate (3-6 mL/min). The physiochemical properties of the microparticles were strongly affected by carrier composition and atomization air pressure. The optimal formulation: andrographolide 0.6% w/w, CHS 62.2% w/w, HEC 15.5% w/w and Poloxamer 188 21.7% w/w, spray dried using solution viscosity 15 cP, atomization air pressure 1.1 bar and feed rate 3 mL/min, was selected according to its particle sizes (3-5 µm) with rough morphology, encapsulation efficiency (54.47%) and release behaviors (22.31%/h and 89.23% within 4 h). Good physical, chemical, and thermal stabilities under room storage condition (28 ± 2 °C, 50% relative humidity) were also proven. Importantly, it demonstrated potent antiviral activity against Influenza A/H1N1, achieving a 3.3-log₁₀ reduction in viral titer with 99.95% inhibition. Overall, this aqueous-based carrier approach and spray-drying technique offer a stable and effective inhalable formulation for localized treatment of influenza infections.