PROZINC is a new genetically-modified PZI-type insulin manufactured by Boehringer-Ingelheim and now approved in the US.
It is labelled specifically for use in cats and is reasonably effective for feline use. It has similar action profile to other PZI insulins, which is fortunate since most of these are now unavailable.
Boehringer Ingelheim Vetmedica was the purchaser of the PZI Vet franchise from IDEXX. ProZinc is a manufactured (not compounded) U-40 insulin with FDA approval for use in diabetic cats. Dosing is expected to be similar to PZI Vet insulin.
According to a BIV technical representative, during efficacy trials cats were switched from PZI Vet insulin to ProZinc in a 1:1 dosing ratio and they did "well." It comes in 10ml bottles and has a shelf life of two years from the date of manufacture. Like other insulins it must be kept refrigerated. Generally ProZinc should be given twice a day. Its characteristics (onset, peak, duration etc.) should approximate if not mirror the old PZI Vet insulin. Since this is a new insulin [Nov 2010] and the supply is on "allocation," supplies may be limited during the immediate future. It is available online, though some vets and some pharmacies.
More on it here.