Carfentanil Is a very potent fentanyl-by-product initially circulated in the mid-eighties to be a normal anesthetic for large animals including elephants. At present, carfentanil nonetheless sees professional medical and scientific use as a radiotracer for positron emission tomography imaging, associated with its superior affinity for MORs in brain tissue [14]. https://chemicalglobe.com/product-tag/protonitazene-for-sale/