March 29, 2023

Phenylbutazone (“Bute”, Phenylcare®) has been identified as an adulterant in illicit drug material. In a review of case data from NMS Labs from 2016-2021, 116 seized drug samples  from Pennsylvania were identified as containing phenylbutazone. This represents a small percentage of total samples analyzed during the time frame. Xylazine, which is now a national concern, first emerged in the northeast (principally Pennsylvania) before spreading across the United States. As phenylbutazone has been gaining prominence in Pennsylvania over a five-year period, the possibility exists that it too can spread nationwide. This adulterant was most frequently observed in samples containing heroin, fentanyl and/or fentanyl derivatives. In addition to illicit drug samples, there have been reports in the literature of adulteration of herbal medicines and supplements with phenylbutazone and self-medication with phenylbutazone prescribed by veterinarians. The serious adverse effects of phenylbutazone can include gastrointestinal bleeding, liver and kidney damage, and blood disorders.