Identification of <i>N</i> ‐pyrrolidino protonitazene in suspect tablets encountered at an international mail facility

One of the United States Food and Drug Administration's (FDA) National Forensic Chemistry Center (NFCC) international mail facility (IMF) satellite laboratories received suspect light blue, round tablets debossed with "PERCOCET 5" on one side and half score on the other side. Although legitimate products with these characteristics contain acetaminophen and oxycodone, the suspect tablets examined in this study were found to contain caffeine by an FDA satellite laboratory. Based on the presence of this unlabeled ingredient and having markings that would indicate a controlled substance, the tablets were recommended for further analysis by NFCC's full-service laboratory. Preliminary analysis using liquid chromatography with mass spectrometric detection (LC-MS), the full-service laboratory confirmed the presence of caffeine and also determined that the tablets contained a nitazene-type compound. Qualitative method development using LC-MS permitted the ability to identify this compound as N-pyrrolidino protonitazene, while ruling out closely related compounds N-pyrrolidino isotonitazene and N-piperidinyl etonitazene. Quantitative method development using LC-MS determined that the tablets contained an average of 99 ± 16 μg N-pyrrolidino protonitazene per tablet. This finding is alarming considering that this compound reportedly has 25 times the potency of fentanyl. Although this is not the first time this nitazene analog has been reported, this case study adds additional information for identifying this compound. Since first being identified in these tablets, N-pyrrolidino protonitazene has been encountered with increasing regularity by this laboratory in other tablets with different colors, shapes, and markings. This compound has also been identified in tablets containing other drug substances.