Eli Lilly starts purifying insulin, but faces yield problems

The Eli Lilly team started off with Collip’s recipe.  Within a month they were producing insulin.  On June 19th, they sent Banting their first shipment of 50 units. By the end of July, they had optimized alcohol concentrations, temperature, and other factors.  They were averaging 1,200 units of insulin per week.

Yield was an important parameter in the extraction of insulin.  Yield measured the quantity of insulin extracted per pound of pancreas.  In the very early production runs, the Eli Lily team had isolated less than ½  unit per pound of pancreas. By September, Eli Lilly was obtaining 100 units per pound of gland.  This increase in yield provided sufficient insulin for all the current patients in Toronto.  But to supply other patients, the Eli Lilly team would need to scale up their production.

Large equipment began arriving in Eli Lilly’s building 20 that August.  The equipment was installed, and its operation was scheduled to begin by the first of October.

However, Lilly ran into the same problem that Collip had at Connaught Laboratory, when he tried to scale up production.  The insulin was deteriorating rapidly and was contaminated.  Physicians reported variable patient response and an increase in abscesses, a sure sign of contamination.