January 20, 2022

Today the U.S. Food and Drug Administration approved Zorbium (buprenorphine transdermal solution), the first transdermal buprenorphine animal drug intended to control pain in cats after surgery.

Buprenorphine is an opioid pain medication that works by acting on pain receptors in the central nervous system. Zorbium is a solution that is applied to the skin at the base of the neck of the cat and is rapidly absorbed into the layers of the skin. It provides pain relief within 1 to 2 hours following administration and continually releases buprenorphine into the body over a period of days. A single application provides pain relief to the cat for four days. Because Zorbium is a long-acting transdermal solution applied in the veterinary hospital, it may eliminate or reduce the need for cat owners to administer additional pain medications.  

This approval gives veterinarians an additional option for controlling postoperative pain in cats.  The FDA previously approved Simbadol, an injectable buprenorphine, for use in cats. The FDA also previously approved a nonsteroidal anti-inflammatory drug, Onsior, as a tablet and injection for use in cats for postoperative pain. Zorbium is the first buprenorphine product the FDA has approved that is applied to the cat topically. 

Zorbium is a DEA Schedule III opioid and was approved with a boxed warning, which is the strictest warning than can be issued for a drug. The label for Zorbium highlights important human safety warnings regarding the abuse potential, human exposure risks, and additional information about drug misuse, abuse, and addiction. The label also includes detailed information regarding how to safely handle and administer Zorbium and what to do if you are accidently exposed to the drug. Zorbium should only be administered in a veterinary hospital by veterinarians or veterinary technicians who are trained in the handling of potent opioids. It is not to be dispensed for administration at home by the pet owner. 

A clinical study was conducted in client-owned cats to evaluate the effectiveness of the drug to control pain after an elective surgery. The cats were of various breeds and between 4 months and 5 years of age. The cats received either Zorbium or a placebo solution without buprenorphine 1 to 2 hours before surgery. All cats received a short-acting pain medication and a local anesthetic as well. 

Each cat was assessed for pain before surgery and at multiple timepoints after surgery, starting from the time the cat entered recovery from anesthesia to 4 days post-surgery. If the cat’s pain was not adequately controlled, it was given a different pain medication and considered a treatment failure. More cats in the treatment group were determined to have adequate pain control for 4 days following surgery compared to the control group.  

The adverse reactions observed from the time the cats were anesthetized until the cats were in recovery after surgery included high or low body temperature, high or low blood pressure, fast heartbeat, and sedation. These reactions were seen in both the treatment and control groups and are commonly seen in cats after general anesthesia and surgery. The adverse reactions noted after the cats were awake from anesthesia and surgery included high or low body temperature, high or low blood pressure, sedation, and increased breathing rate. During the days after surgery, the most common adverse reaction in cats administered Zorbium was increased body temperature. Additional findings observed in cats administered Zorbium in safety studies included dilated pupils, constipation, and abnormal behavior such as hyperactivity, agitation, restlessness, and aggression. 

Zorbium is sponsored by Elanco US Inc. based in Greenfield, Indiana. 

For more information: 

• Freedom of Information Summary 
• The Opioid Epidemic: What Veterinarians Need to Know