Preparation and characterization of a powder manufactured by spray drying milk based formulations for the delivery of theophylline for pediatric use

The study considered different fat content cow milks to deliver theophylline orally. Powders were obtained by spray drying theophylline dispersed in fresh milk according to a full factorial design of experiments. The correlation of the independent (milk fat content, skimmed to whole milk, theophylline fraction, and drying temperature) with the dependent (yield of the process and residual moisture content of the powder, particle size and distribution, density, surface polarity and theophylline content) variables enabled the construction of a mathematical model and a desirability function to predict the optimized levels of the variables. Good predictability was achieved for density, fairly good for yield, moisture content, surface polarity and yield whereas theophylline content and particle size were poorly predicted. Powders with up to 60% theophylline presented spherical (3.7 µm) and narrow sized distribution particles, with high density (1.6 g/cm−3) in high yields (>70%), stable for 6 month (25 °C/65%RH) in a closed container and for no longer than 2 day, after reconstitution in water due to bacteria growth (no pathogens) without signs of crystallinity. Preparations obtained with low fat milk were less stable than high fat content milk. Therefore, fresh milk can be transformed into stable powder compositions to prepare oral solid/liquid dosage forms to deliver individualized doses of theophylline.