The makers of the veterinary insulin product Vetsulin are stressing the need to transition diabetic animals off of the drug “as soon as possible.”

The U.S. Food and Drug Administration recently issued a product alert on Vetsulin when amounts of crystalline insulin in the formulation were found to be out of specification in some batches of the product. Vetsulin manufacturer Intervet/Schering Plough Animal Health sent a letter to veterinarians in November urging them to begin transitioning diabetic patients off Vetsulin due to predicted shortages in product availability.

Last week, Intervet issued a follow-up letter to veterinarians, which had a more urgent tone than the first communication from the company. In the letter, Intervet Director of Technical Services Christopher Pappas Jr., DVM, emphasized that veterinarians should transition dogs and cats from Vetsulin to other products as soon as possible, and to start new patients on other drugs.

“Going forward, we will have very limited supplies of Vetsulin and will have to employ tight product allocations,” Pappas wrote. “It is likely there will not be sufficient product available to meet the needs of the market as soon as early 2010. We strongly encourage you to take action to inform and meet with your clients to set-up an orderly conversion to other insulin products for all your canine and feline diabetic patients.”

In response to the 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 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.

Intervet reiterated the need for vigilance when transitioning patients to human insulin products, especially in terms of dosage.

“As NPH insulin, insulin glargine and insulin detemir are human insulin products and analogs, they have a concentration of 100 IU/ml,” the company said. “It is therefore imperative that U-100 syringes are used when administering the U-100 insulin, for dosing accuracy. If U-40 (Vetsulin) syringes are used with U-100 insulin, the animal could receive 2.5 times the intended dose of insulin.”

The exception is Prozinc, recently approved by the FDA for use in cats. Prozinc has a concentration of 40 IU/ml, the same as Vetsulin, according to Intervet.

Vetsulin is sold as Caninsulin outside of the United States. So far no other countries have issued product alerts on Caninsulin, but Health Canada did publish an advisory on its website. Health Canada said it is requesting that veterinarians “monitor their patients receiving Caninsulin for any changes in onset or duration of activity, or for any signs of hyperglycemia or hypoglycemia.” However, the Canadian agency stopped short of recommending that veterinarians transition their patients to other drugs.

For more information on Vetsulin, see www.vetsulin.com. Or call Intervet’s technical services department at (800) 224-5318.