Patent Title:
Spray freeze-dried compositions
Assignee:
Powderject Research Limited
Inventors:
Yuh-Fun Maa, Steven Prestrelski, Terry Burkoth
Patent:
Summary related to Ultrasonic Spray Freeze Drying:
Liquid formulations were delivered by a peristaltic pump at a flow rate of 2.0 mL/min into an ultrasonic atomizing system. The nozzle is equipped with a quasi-electric quartz crystal capable of vibrating at a specific frequency that determines the size of the droplets. A 60 kHz spraying nozzle produces droplets mostly within the range of 20-80 μm. Atomized droplets were sprayed into a liquid N2-containing pan (16 cm in diameter by 6 cm in height). For formulations subjected to the spray-freezing/thawing experiment, the frozen powder was transferred to a glass vial and thawed at ambient conditions. For frozen droplets undergoing drying, the pan containing frozen particles in liquid nitrogen was transferred to a pre-cooled (−55° C.) shelf freeze dryer. The liquid nitrogen evaporated in a few minutes. The freeze-drying condition was set at −25° C. for 18 hours and 20 ° C. for 10 hours. The ramping rate was 1° C./minute consistently. The vacuum pressure was 100 ml throughout the cycle. After drying, the powder-conaining pans were transferred into a dry box purged with nitrogen (at <30% relative humidity) for powder collection. The same lyophilization cycle was used for liquid formulations without SF with freezing achieved by storing in a −20° C. freezer overnight.
