(189ad) Dropwise Additive Manufacturing for Pharmaceuticals

In recent years additive manufacturing (AM) technology has attracted considerable interest for its potential applications to on-demand manufacturing of dosage forms with individually adjusted doses, which is a necessity for implementation of precision medicine, and for development of a robust manufacturing platforms for early drug development or continuous manufacturing. Commensurate with the level of interest is the variety of different technologies based on two-dimensional (2D) or three-dimensional printing (3D) techniques, all of which present the common advantages of precision and flexibility in dosing inherent to AM processes. However, differences exist in the printing material requirements and in the achievable production rates for the process, both of which must be considered when proposing implementations in the context of compounding in clinical/pharmacy settings or full-scale production.

Of the AM techniques, the system based on the drop-on-demand method (2D printing) for fluid deposition/dispensing has demonstrated the capacity to serve as flexible manufacturing platform for pharmaceutical dosage forms, with doses in amounts of 1-100 mg active ingredient produced from printing materials which ranged from drug solutions to drug-polymer melts and concentrated suspensions of micronized particles [1, 2, 3]. Most recently demonstrated was the development of the system for precision dispensing of micronized powders by processing them as particle suspensions, which, as a fluid-based method, avoids powder flow issues and may readily be adapted to new particulate materials using dimensional analysis [3, 4]. For dosage units which contain 100mg of active drug, production rates of up to 2000 doses per hour, with product RSD < 2%, have been achieved with suspension processing [3, 4]. This system uses the drop-on-demand printing method to deposit drops on to a prepared substrate, wherein the content of each dose is determined by the number, volume and composition of drops; consequently, quick adjustments to dosage unit properties may be made by changing the deposited fluid volume, and/or composition.

In this work the capabilities of the dropwise additive manufacturing process for pharmaceuticals production are described, with particular emphasis given to dosage forms produced by printing of micro-particle suspensions. Applicability of the system to precision medicine is demonstrated through the production of oral solid dosage units from multiple drug compounds at low to high dosage strength levels; discussion of process monitoring tools for real-time prediction of dosage properties during production runs and characterization of drug product properties is included. In the context of process development, high speed photography of the drop formation dynamics is combined with an in-house image analysis tool to provide quantitative evaluation of performance metrics, such as process throughput and drop volume reproducibility, which are then related to particle properties in the printing materials. Presented together, these results demonstrate the capability of the dropwise AM system for dose production at multiple manufacturing scales.

References

1. Hirshfield, L., Giridhar, A., Taylor, L. S., Harris, M. T., & Reklaitis, G. V. (2014). Dropwise additive manufacturing of pharmaceutical products for solvent-based dosage forms. Journal of pharmaceutical sciences, 103(2), 496-506.
2. Içten, E., Giridhar, A., Taylor, L. S., Nagy, Z. K., & Reklaitis, G. V. (2015). Dropwise additive manufacturing of pharmaceutical products for melt-based dosage forms. Journal of pharmaceutical sciences, 104(5), 1641-1649.
3. Radcliffe, A. J., Hilden, J. L., Nagy, Z. K., & Reklaitis, G. V. (2019). Dropwise Additive Manufacturing of Pharmaceutical Products Using Particle Suspensions. Journal of pharmaceutical sciences, 108(2), 914-928.
4. Radcliffe, A. J., & Reklaitis, G. V. (2017). Dropwise additive manufacturing using particulate suspensions: feasible operating space and throughput rates. In Computer Aided Chemical Engineering (Vol. 40, pp. 1207-1212). Elsevier.