Phentermine involvement in fatal drug overdoses in Tennessee, 2019-2022

Phentermine, one of the most-commonly prescribed pharmaceuticals for weight-loss in the United States (US), has appeared on toxicology and listed as a cause of death in fatal drug overdoses in the state of Tennessee. This study aims to evaluate phentermine's involvement in fatal drug overdoses in the state of Tennessee.

We used Tennessee State Unintentional Drug Overdose Reporting System (SUDORS) data and controlled substances monitoring program data (CSMD) to evaluate demographics, prescription history and co-occurring substances on toxicology in phentermine-positive cases compared with all other SUDORS cases from January 1, 2019 to June 30, 2022. A subset of these cases which listed phentermine as a cause of death was also assessed.

We identified 51 phentermine-positive cases, with a subset of 20 that listed phentermine as a cause of death. When compared to all SUDORS cases, a higher proportion of cases that listed phentermine as a cause of death were White race, females, and aged 35-44. Additionally, in all phentermine-positive cases, 41% (21) of decedents had not had a phentermine prescription dating back to 2012 and 20% (Lee et al., 1998) did not have one within the last 30 days. While there was a slight decline each year in the number of phentermine-positive cases, the number of cases that listed phentermine as a cause of death remained relatively consistent, with 95% (19) of cases having different prescriptions and/or illicit drugs listed as a cause of death along with phentermine.

Phentermine was listed as a cause of death in 20 fatal drug overdoses in TN. Our findings suggest there may be differences in the characteristics of these decedents when compared to all SUDORS decedents, including distribution of age, gender, and race. We also found a large presence of other prescription and illicit drugs in toxicology and cause of death along with phentermine, as well as evidence of use of the drug without a prescription. Given the lack of currently available data about non-prescribed phentermine use and its involvement in fatal drug overdoses elsewhere, a need exists to both expand surveillance capabilities and broaden research to better inform policies governing this drug in the US and internationally.