Application of high-resolution mass spectrometry to determination of baclofen in a case of fatal intoxication

Phenibut, a GABAB Agonist, Detected in a Fatality

Phenibut, a GABAB agonist structurally similar to baclofen, is not approved for medical use in the United States, but is available through internet suppliers for recreational use. Calls to poison control centers for phenibut have increased over the last five years, and there are many case reports of severe acute intoxications and withdrawals requiring hospitalization. This case report describes the autopsy and toxicology findings of a 26-year-old male found dead at home with phenibut containers on scene. Autopsy findings and routine toxicology testing were generally unremarkable. Scene findings prompted the validation of a qualitative liquid chromatography tandem mass spectrometry method that confirmed the presence of phenibut in blood and urine.

Baclofen: To Screen or Not to Screen in Postmortem Blood?

Baclofen (BLF) has been prescribed in the UK since 1972 for the alleviation of spasticity. However, evidence suggests BLF is also recreationally misused. It has been associated with ethanol, gamma-hydroxybutyric acid (GHB), pregabalin (PGL) and gabapentin (GBP) use/abuse, and deaths have been reported. With current postmortem (PM) toxicological screening approaches, BLF is not routinely included in the general drugs screen and is only screened for if specifically mentioned in the case documents. The extent of BLF misuse is thus unclear. This study was carried out to determine the prevalence and concentrations of BLF in Coroners' toxicology, to investigate whether BLF misuse with ethanol, GHB, PGL and GBP is causing death and to determine the potential extent of the underreporting of BLF-associated deaths. Between 1 January 2016 and 31 December 2017, 3,750 PM femoral vein bloods were screened for BLF; all positive cases were quantified. Only 0.56% of samples screened positive for BLF, with concentration ranging from 0.08 to 102.00 µg/mL (median = 0.28). It was determined that if routine analysis without additional screening of BLF had been performed, 43% of BLF positives cases would have been missed. However, given the low incidence of detection, this only represents 0.25% of the cohort. Likely illicit use of BLF with GHB was seen in one case only. Death from the recreational use of BLF with PGL and GBP was not observed. Only two cases positive for BLF had an ethanol concentration of ≥50 mg%. Two cases of presumed intentional overdose of BLF were observed. This study highlights that although BLF abuse may be occurring, deaths are rare. It is therefore not cost- or time-effective to screen for BLF in all PM cases. With BLF currently being investigated for the treatment of alcoholism and withdrawal symptoms of illicit drug use, BLF-related deaths may rise in the future.