Bacterial contamination dealt Vetsulin a blow late last week, with the U.S. Food and Drug Administration (FDA) sending out notice that starting in March, the drug no longer will be manufactured. 

The notice came nearly a year-and-a-half after Vetsulin stability issues surfaced, inciting warnings of “unpredictable onset and duration of action” for the only FDA-approved insulin to treat diabetes mellitus in dogs and cats. The problem, regulatory officials reported, stemmed from varying amounts of crystalline zinc insulin in the formulation.

Despite the sterility and stability troubles, an insider with the Intervet/Schering Plough Animal Health is optimistic that Vetsulin will reemerge, provided the drug receives a nod from the FDA. 

“Our dedicated team has been and still is working diligently to verify and appropriately correct the original stability issue, and we have made progress,” writes company spokeswoman Sharon Dilling in an e-mail to the VIN News Service. “Further activity is needed before we make the necessary regulatory submissions.”

That’s good news for veterinarians who swear by this insulin, though it’s unclear how long it will take Vetsulin to come back to market or if it ever will.

On Friday, the FDA alerted the public to suspicions that new batches of Vetsulin could be contaminated with bacteria, according to internal sterility tests. The problem is not believed to affect distributed product.

Intervet officials followed with a news release this morning, reiterating the contamination concerns and requesting that veterinarians change their patients from  Vetsulin, to one of the human insulins by the end of February.

The FDA has been advising veterinarians to discontinue using Vetsulin since the stability issues arose in November 2009.  The agency asked practitioners to closely monitor their diabetic patients on Vetsulin for signs of hyperglycemia or hypoglycemia.

But with few insulin options for canine patients in particular, veterinarians pushed for continued access to the drug. Last May, the Vetsulin Critical Need Program was born — intended for animals that, in the medical judgment of a veterinarian, could not be effectively managed by other insulin products.

For the last nine months, the Vetsulin Critical Need Program has been veterinarians’ only access point to the drug. Now that loophole is being closed, at least temporarily.

Members of the Veterinary Information Network (VIN), an online community for the profession, are lamenting the demise of an insulin that was one of the few choices for canine diabetic patients.   

“If you can’t get a diabetic dog regulated, they’re dead, as owners won’t tolerate urination in the house,” says Dr. Sherri Wilson, a VIN consultant who’s boarded in internal medicine. “And it’s expensive to get a dog re-regulated on an insulin. Having to change to a different insulin could mean the difference of a dog living or dying.”

Testing blood glucose curves can cost owners hundreds of dollars over multiple attempts. The process involves testing an animal’s blood sugar levels during the course of a day following an insulin injection.

“It can take at least three or four blood glucose curves before you can find an insulin and dosage that works,” Wilson says. “You can teach an owner to do this at home, but they have to buy a glucometer and testing strips. There’s no way around it. It’s expensive.”

The goal is to find an insulin that will regulate a pet’s blood sugar with twice-daily injections. Anything more than that often is unmanageable for owners, Wilson says.

While many DVMs have turned to a human insulin called NPH, its intermediate duration of action has proven to be too short for many canine patients. Frustrated and looking for alternatives, practitioners have been trying the long-acting human insulin Detemir (brand name Levemir), an insulin often used to manage diabetes in cats.

Wilson has shared her experience using Detemir in dogs with her colleagues on VIN. In an online discussion, she notes that Detemir often provides the longer duration of action that veterinarians and owners are seeking. At the same time, she issues a warning:

“Note that it is really potent stuff and the starting dose is different than other insulins. Start Detemir at 0.1 unit/kg BID. Wait one week, then do the first curve and adjust from there. It is so potent that it may not be useable in some small dogs (for whom the starting dose is lower than can be measured accurately).”