Production and characterization of spray-dried theophylline powders prepared from fresh milk for potential use in paediatrics

Objective: This work evaluates the potential of using fresh milk to deliver theophylline to children. Methods: Theophylline–fresh milk systems were prepared using different solids ratios (0 : 1–1 : 0) and three fat contents in commercial milks (low, medium and high), which were spray-dried at different inlet air temperatures (T_inlet – 105, 130 and 150 °C). The process was evaluated for yield and the resulting powders for moisture content (MC), particle size and shape, density and wettability. Theophylline–milk potential interactions (differential scanning calorimetry (DSC) and FT-IR) and chemical (theophylline content) and microbiological stability of powders (shelf and in-use) were also evaluated. Key Findings: The production yield (13.6–76.0%), MC (0.0–10.3%) and contact angles in water (77.29–93.51°) were significantly (P < 0.05) affected by T_inlet, but no differences were found concerning the mean particle size (3.0–4.3 μm) of the different powders. The milk fat content significantly (P < 0.05) impacted on the density (1.244–1.552 g/cm³). Theophylline content remained stable after 6 months of storage, before extemporaneous reconstitution. After reconstitution in water, low-fat milk samples (stored at 4 °C) met the microbial pharmacopoeia criteria for up to 7 days. No theophylline–milk components interaction was observed. Conclusion: Spray-dried milk-composed powders may be used as vehicles for theophylline delivery in paediatrics following further characterization and in-vivo evaluation.