How is the insulin content of insulin pens synthesized? Does anyone here have any experience?
Assuming genetically engineered bacteria/yeast are used to produce the molecule, is it isolated from the cultures in large quantities in its pure form and then administered into cartridges that are in these pens?

Insulin was just a practical example. If anyone here has any experience with overall hormone synthesis I'd really like to hear the process and its restrictions. I have a project in mind for a certain insect hormone but I can't find any info. on how it could be synthesized and acquired in large quantities.