Continuous processing is pretty much a “given” in many industries — even the larger pharmaceutical industry that makes synthetic small-molecule drugs. But the concept has only just begun to make inroads with biomanufacturers, who have until recently worked mainly in batch or fed-batch mode. Single-use technologies largely have enabled them to consider the possibility of process intensification and going continuous. In support of this month’s featured report, I asked contributor Margit Holzer, PhD (scientific director at Ulysse Consult S.a.r.L in Luxembourg) a few general questions on the topic.
One question often asked of perfusion and other continuous culture approaches is “How do you define a batch?” Some experts say it isn’t even necessary to do so. Others say you can describe batches in terms of time. What do you think?
HOLZER: It is important to recall that traceability of the whole batch history of a drug substance or product is absolutely necessary for CGMP production. So there is no choice. A batch also needs to be defined for continuous upstream operations. This becomes especially crucial during investigations or product recalls. In the case of continuous production, a batch may correspond to a defined fraction of production.
The batch size of a continuous upstream process can be defined, for example, by a fixed quantity (e.g., volume, mass, or activity units of product) of harvested product; the amount produced within a fixed time interval (e.g., hours of production, residence time) between harvests; or the number of cell generations or doubling times to be produced, collected, and further treated in downstream processing as one batch. In addition, a minimum titer and/or viability and/or other quality requirements can be specified as acceptance criteria for pooling with the harvested product to assure batch homogeneity. For all those cases, downstream processing capacity must be in line with the harvested quantity of material.
What’s the most challenging part(s) of downstream processing to do continuously? Continue reading “Continuous Processes: Disposables Integrate Upstream and Downstream Processing – Featured Report”