Figure 2.

Rate of posts discussing fentanyl analogs on substance message boards, 2010–2017. Note: The fentanyl analogs examined were those identified from the list of terms used in Figure1. The word2vec and fastText algorithms were then run for each of the analogs to identify any spelling variants that existed. Terms used to identify the various fentanyl analogs underwent expert review and included carfentanil, carfentanyl, carfentanils carfent, csrfentanil, carefentanil, carfentnyl, carfentail, carfentenil, carfentenyl, carfentinil, carfentynal, carf; butyrfentanyl, butyrfent, butyrylfentanyl, butyr, butyryl, butryfentanyl; furanylfentanyl, furanylfent, furanyl, fuf; acrylfentanyl, acryloylfentanyl, acrylfent, acryl; sufentanyl, sufentanyl, sufenta; lofentanil, lofentanyl, lofent, ocfentanyl, ocfentanil, acetylfentanyl, acetylfent.