Veterinarians who are involved with the Vetsulin Critical Need Program will need to find another source of treatment for their diabetic patients.

The company that manufactures the drug, Intervet/Schering-Plough Animal Health, issued notices to veterinarians and consumers this week, alerting them that the Critical Need Program (CNP), designed to provide the product to critical patients, will be ending as of Feb. 7, 2011.

"Quality tests showed that the sterility of the most recent batch of Vetsulin manufactured for the CNP may be compromised by bacterial contamination," the letter says. "This batch of Vetsulin has not been released and additional batches are not being manufactured at this time. We, therefore, cannot supply the program and it must be discontinued."

The contamination is not the first time there has been trouble with Vetsulin. Late in 2009, the company announced that the product, which is a porcine insulin zinc suspension used to treat diabetes in dogs and cats, was possibly unstable due to varying amounts of crystalline zinc insulin in the formulation. This latest announcement is unrelated to those stability problems, the company said.

When the stability issues were first announced, Intervet and the U.S. Food and Drug Administration (FDA) urged veterinarians to switch diabetic patients over to different insulin products. The Critical Need Program was started in May 2010 to provide a limited supply of Vetsulin to patients that were deemed unsuitable for transition to other insulin products.

The FDA said in a statement that a batch of Vetsulin intended for the Critical Need Program in November 2010 "failed critical manufacturing tests which are routinely conducted to assure consistency and quality of the drug."

Intervet said there is enough usable Vetsulin available to last through February, but after that, diabetic animals will need to be treated with different insulin products. The company apologized for the situation, and promised to provide access to an educational webinar with step-by-step instructions on transitioning patients off Vetsulin. The webinar will be available on the website www.vetsulin.com.

In response to the original 2009 product alert, the American Animal Hospital Association (AAHA) consulted members of its Diabetes Guidelines Task Force. Task force members Richard Nelson, DVM, of the University of California at Davis, and Deb Zoran, DVM, and Audrey Cook, BVM&S, of Texas A&M University developed the following recommendations for using alternative insulin products:

For dogs, use the human recombinant NPH insulin at an initial dosage of 0.25 IU/kg twice daily, and adjust insulin based on clinical response and glucose measurements. You will be starting over with diabetic regulation when you switch to a new insulin product.

For cats, you can use a long-acting insulin such as the human recombinant PZI (ProZinc, Boehringer Ingelheim) or insulin glargine (Lantus, Aventis Pharmaceuticals). Start with 1 IU per injection twice a day. The starting dose will be the same for both the PZI and glargine. Then, proceed to adjust the insulin dose based on clinical response and glucose measurements. You will be starting over with diabetic regulation when you switch to a new insulin product.

When transitioning animal patients to human insulin products, veterinarians should pay close attention to the dosages. Human insulin products and analogs have a concentration of 100 IU/ml, so U-100 syringes must be used when administering the U-100 insulin in order to provide accurate dosing. If U-40 (Vetsulin) syringes are used with U-100 insulin, the animal could receive more than double the intended dose of insulin.