Trial Finds Patients Receiving CroFab Antivenom Less Likely to Use Opioids for Pain Control

BTG plc (LSE: BTG), the global healthcare company, today announced the publication of a trial, "Antivenom Treatment is Associated with Fewer Patients Using Opioids after Copperhead Envenomation" in the Western Journal of Emergency Medicine (WestJEM).

“In a randomized, double-blind, placebo-controlled, clinical trial of CroFab for treatment of copperhead snakebite, patients that received CroFab were less likely to use opioids for pain control during recovery,” said Dr. Charles Gerardo, Chief of Emergency Medicine at Duke University and expert in copperhead snake envenomation. “This is completely consistent with antivenom’s effect on tissue injury and improved recovery. No patients reported use of opioids once they had regained full function. As the CroFab patients recovered more quickly, they required a shorter duration of opioids.”

The secondary analysis was performed using data from a randomized clinical trial designed to determine the effect of CroFab on limb injury recovery following mild to moderate copperhead envenomation. The original trial results were published in the Annals of Emergency Medicine in 2017 as “The Efficacy of Crotalidae Polyvalent Immune Fab (Ovine) Antivenom Versus Placebo Plus Optional Rescue Therapy on Recovery from Copperhead snake Envenomation: A Randomized Double-Blind, Placebo-Controlled, Clinical Trial.”

“Exposure to opioids as a result of an initial prescription from the emergency department may contribute to long term opioid abuse and addiction,” said Dr. Caroline Freiermuth, Associate Professor of Emergency Medicine at the University of Cincinnati. “Patients who continue to use opioids for more than five days following an initial opioid prescription have a higher risk of ongoing opioid use at a year than those patients who have stopped. When assessing the efficacy of treatments for painful diseases such as snakebite, we should more consistently assess the treatment’s impact on opioid use as was done in this study.”

Seventy-four patients were enrolled in the parent trial. Forty-five received CroFab. Twenty-nine received a placebo. A smaller proportion of patients treated with CroFab reported opioid use, nearly 41 percent versus nearly 61 percent of those in the placebo group. The proportion of patients using opioids remained smaller in the CroFab group at every follow-up time point.

The resulting model estimated the odds of using opioids after hospital discharge among those who received placebo was nearly 6 times that of those who received CroFab.

A secondary analysis, “Early Administration of Fab Antivenom Resulted in Faster Limb Recovery in Copperhead Snake Envenomation Patients,” showing early treatment with CroFab led to faster limb recovery was published in Clinical Toxicology in 2018. Another secondary analysis, “The Validity, Reliability and Minimal Clinically Important Difference of the Patient Specific Functional Scale in Snake Envenomation,” was published in PLOS One this year.