Shortage of ProZinc causes a scramble for feline insulin.
Update - As of September 12th, ProZinc is available again in limited supplies.
I own a busy cat practice, and we have a lot of diabetic cats in the practice. Most diabetic cats require insulin injections to achieve good control of their diabetes. Years ago, most veterinarians administered a type of insulin called protamine zinc insulin (PZI). This insulin was derived mainly from cattle. It was 90% beef, 10% pork in origin. Cats respond well to bovine insulin, because the molecular structure of feline insulin most closely resembles bovine insulin; they differ by only one amino acid. When recombinant human insulin became available, the demand for PZI insulin in humans disappeared, and it was not feasible for companies to continue to produce PZI insulin solely for use in domestic animals. Veterinarians began using recombinant human insulin to treat diabetic cats.
Currently, there are several types of insulin products available for cats with diabetes. Every practitioner has their own personal favorite. Some people use insulin glargine (brand name Lantus), while others prefer a type called protamine zinc insulin. When Lantus became available, there were high hopes that this relatively long-acting insulin could be given only once daily. Alas, this turned out to not be the case. Cats on Lantus still require twice daily insulin.
The insulin I’ve been prescribing in the last few years is a type called ProZinc. I like it because it’s the only insulin approved by the FDA specifically for use in cats. It is recombinant human insulin; as noted above, they don’t make insulin of animal origin anymore. If a client comes to my practice with a cat that has previously been diagnosed as diabetic and is already receiving Lantus insulin, I won’t switch them to ProZinc. Lantus is fine. But for newly diagnosed diabetic cats, ProZinc is what I’ve been prescribing. Their diabetes usually comes under control fairly quickly, with most cats requiring somewhere between 1 and 4 units twice daily.
Lately, it’s been difficult managing all of the diabetic cats in my practice, because there is a nationwide shortage of ProZinc insulin. This is due to a shortage of the ingredient protamine, a protein that slows down the absorption of the insulin, increasing its duration of action.
Initially, when I ran out of ProZinc, I called some referral centers and they were kind enough to either sell me a few bottles, or to let my clients go there with a prescription and pick up a bottle. Then I called some veterinary pharmacies. They had a few bottles, but of course, they were affected by the shortage as well. A few tried to gouge me, asking an outrageous price for a bottle. I’ve made note of those pharmacies and have vowed never to deal with them again.
Now, it seems there’s not a bottle of ProZinc to be had anywhere. I’ve spoken with some veterinary pharmacies that have the ability to compound their own generic protamine zinc insulin (PZI). They tell me that it’s the same potency as ProZinc, so it’s not necessary to re-regulate the diabetes. Cats receiving 3 units of ProZinc twice daily should receive 3 units of generic PZI twice daily.