Warning as pentobarbital is found in counterfeit pills in US

Researchers in the US have warned that pentobarbital – a drug used to euthanise pets and to assist in suicides – is starting to appear in counterfeit pills sold on the street.

Pentobarbital is a Schedule II/III short-acting barbiturate, also used to execute people convicted of capital crimes, that has limited use in human healthcare but has been found mixed with fentanyl and other ingredients in counterfeit oxycodone or alprazolam tablets, along with other barbiturates like phenobarbital and butalbital.

The National Drug Early Warning System (NDEWS) research team, led by Joseph Palamar of NYU  Grossman School of Medicine, report in the journal Drug and Alcohol Dependence that the discovery, along with a recent seizure of 5 kg of pentobarbital smuggled into the US from Mexico, suggest that monitoring for the drug should be stepped up by enforcement agencies. As little as 2 to 10 grams of oral pentobarbital can lead to death, although there are cases of people surviving exposures of up to 20 g.

Extremely powerful synthetic opioids like fentanyl have been driving an epidemic in overdoses and opioid-related deaths in the US in recent years, often through exposure to counterfeit tablets sold on the street - but the study shows that law enforcement needs to be aware of possible shifts in illicit supply.

Earlier this year, the Drug Enforcement Administration (DEA) said it had busted a drug smuggling ring, seizing the pentobarbital shipment, which was reportedly being prepared for sale as heroin. That prompted a request from a reporter for information on pentobarbital from the NDEWS, and resulted in the just-published paper.

Across its network of 16 sentinel sites, the organisation found evidence of at least 12 fatal exposures linked to use from 2020 to 2022, but acknowledges that "toxicology and self-report data are lacking." The DEA has also recorded 259 thefts, diversions or other types of losses associated with the drug.

"We at NDEWS have established a potential signal that illicit pentobarbital availability has begun to expand in the US," write the authors, who are concerned that "unknown exposure can occur if the drug is mixed into counterfeit pills or sold in powder form represented to be another drug."

They note that pentobarbital test strips are available and could be incorporated into field-testing strategies if pentobarbital adulteration becomes widespread. Signs of pentobarbital overdose include confusion, agitation and drowsiness, shallow breathing, headaches, and slurred speech.

Image source: Global Pharma Health Fund