Orally disintegrating tablets (ODTs) were freeze dried in blisters using the Lyostar® II SMART™ Freeze Dryer Technology. ODT formulations either without non-water soluble particles (placebo) or containing large fractions (717 mg) of taste-masked naproxen sodium (NaS) granules were freeze dried. The process data revealed differences between ODTs with and without embedded granules in the pressure rise curves as well as in the shelf (inlet) temperature adjustments during freeze-drying. Pressure rise curves of the placebo ODTs from eight hours process time showed no distinct temperature-dominated part, and the last optimization step of the shelf temperature to achieve -24.4 °C might be prone to errors. The final shelf temperature of ODTs containing granules was -23.3 °C. The detection of primary drying endpoints using SMART™ Technology or comparative pressure measurements was reliable for both ODT formulations, whereas the application of thermocouples resulted in premature endpoint indication. Product resistance of ODTs containing granules was generally elevated in comparison to ODTs without granules, but increased only slightly over the course of the drying process. In summary, the developed freeze-drying cycle was found applicable for production of elegant ODTs with incorporated taste masked NaS granules.
Keywords: Lyophilization; manometric temperature measurement; microparticles; product resistance.