Carfentanil Is a very strong fentanyl-by-product originally circulated during the mid-eighties for a basic anesthetic for giant animals including elephants. At this time, carfentanil continue to sees clinical and scientific use for a radiotracer for positron emission tomography imaging, associated with its substantial affinity for MORs in brain tissue [14]. https://chemicalglobe.com/product-tag/protonitazene-for-sale-uk/