(391e) Development of a Novel Drying Technology for Drying of Wet API’s
AIChE Annual Meeting
Tuesday, October 30, 2018 - 4:58pm to 5:20pm
In continuous manufacturing, not only the products quality but also its processability have to be considered. Active pharmaceutical ingredients (APIs) have a generally poor flowability since their particles are mostly small, making the powder very cohesive. Moreover, while the API synthesis may be a continuous process, the subsequent steps of filtration, washing and drying are still performed using batch process. This is primarily due to the lack of appropriate equipment.
In terms of linking primary and secondary production, drying is one of the most challenging process steps. Not only does it consume a vast amount of energy, it can significantly change the particle properties, which may often be problematic. In a crystallizer, for example, particle properties are tailored with high precision and should not be modified during the downstream processes. During drying, particle collision or shearing may lead to attrition or agglomeration of single particles, which may affect the final properties of the primary API particles.
In our work, ibuprofen was used as a test substance. The needle-shaped particles make processing particularly challenging and are thus perfectly suited for a processability study. In addition, ibuprofenâs poor flowability may lead to agglomeration and restricted flow in the dryer, affecting the residence time distribution (RTD). Ideally, the RTD should be narrow and no material should be found on the walls and in dead spaces. This novel drying prototype was developed for the challenges occurring when drying cohesive powders. The new drying mechanism was developed for a mass flow of 0.5- 2 kg/h of dry substance, and showed strong improvements compared to available drying equipment. It was tested with material (ibuprofen) having various moisture levels and with different process parameters. Neither the particle size of ibuprofen nor the needle-shaped structure of the primary particles changed due to the drying process, suggesting that the contact-convective drying technology is suitable for drying cohesive materials, such as ibuprofen, at low temperatures. This study indicates that the contact-convective drying technology is a gentle and effective technology, which allows to achieve a final moisture below 1%.