A suspected “bad batch” of drugs that sent at least 27 people in West Baltimore to the hospital last week may have been the result of the powerful synthetic painkiller fentanyl plus at least one new drug not before found in illicit drugs, federal scientists found.

Drug samples collected from the Penn North neighborhood and believed to be tied to the mass overdoses contained N-methylclonazepam, a benzodiazepine derivative with intense sedative effects, said Edward Sisco, a research chemist at the National Institute of Standards and Technology, whose lab now partners with 80 sites, such as needle exchange centers, in 15 states including Maryland, which send in trace amounts of drugs for testing.

“N-Methylclonazepam’s highly sedative effects are consistent with the experiences of those who experienced an overdose in Penn North on 7/10. Many people remained unconscious after receiving naloxone, likely as a result of the presence of N-methylclonazepam,” Sisco wrote in an email, referring to an opioid overdose reversal medication, also often called by its brand name, Narcan, that is used to restore normal breathing.

Naloxone works to reverse the effects of fentanyl but not non-opioids such as benzodiazepines.

Sisco ssaid the federal program had not seen the derivative before in Maryland or any other states where the program tests drug samples.

The aim of the program is to rapidly test drug samples and alert providers and others in the community about what they may be dealing with. They can both warn drug users and prepare for the effects.

The program also found other drugs in the samples from Baltimore including acetaminophen, the pain and fever reducer; caffeine, the central nervous system stimulant; mannitol, a diuretic; and quinine, an antimalarial drug. Sisco said they are all commonly found in drug samples from sites in Maryland.

The lab didn’t say which sites in Baltimore provided samples, which typically come from drug wrappings or bags collected from those who used the drugs.

Experts have said that illicit drug manufacturers frequently add other substances in an attempt to prolong the drug’s effects or make them more powerful. Typically they choose those that are both cheap and available.

That can make the evolving drug supply especially dangerous and tricky for those treating overdoses.

Patients who are suffering from a suspected overdoses usually are treated with naloxone, given the prevalence of fentanyl, which has replaced heroin as a main illicit drug, said Dr. Cheyenne Falat, assistant medical director of the adult emergency department at the University of Maryland Medical Center’s Downtown Campus, which together with the Midtown Campus treated 14 suspected cases.

Falat, who had not yet seen the federal lab’s findings, said otherwise the doctors treat symptoms, which in this case were sedation followed by agitation in some people. She said that can indicate an additive uncovered after the naloxone takes effect or can just be someone’s “fight or flight” response.

“Some of it is guesswork, but guided by many years of seeing symptoms,” she said “Complicating things is we don’t know what is in the formulation.”

The methylclonazepam is a version of other compounds that have been emerging in Maryland.

According to a state report, benzodiazepine derivatives were found in less than 2% of about 400 drug samples that were tested from October to April. The report lists it as an emerging substance in Maryland. Benzodiazepines are a type of drug that can be used to treat anxiety, seizures and insomnia.

Some common types include brands like Valium and Xanax. According to the U.S. Drug Enforcement Administration, people who use opioids may also use benzodiazepines to “enhance euphoria,” but combining the two can lead to overdose, coma and death.

Combining opioids with benzodiazepines is especially dangerous because both drugs cause sedation and make it harder to breathe. In 2021, nearly 14% of fatal opioid overdoses in the U.S. involved benzodiazepines, according to the National Institute on Drug Abuse.

Dr. Enrique Oviedo, chief medical officer for MATClinics, an outpatient addiction treatment program with eight locations across Maryland, said many of his patients consistently test positive for benzodiazepines. Sometimes they are prescribed the medication, but sometimes they are likely unknowingly consuming it because dealers mix it into the illegal drug supply, he said.

“We’re talking about very potent, very sedating drugs, and it’s probably being mixed haphazardly without them really understanding how unsafe the combination is,” Oviedo said.

He said though the U.S. Food and Drug Administration has issued stern warnings about the dangers of combining opioids and benzodiazepines, he still sees some providers prescribing both. He urged health leaders in Maryland to take a closer look at prescribing practices.

“Even though what was in this drug supply wasn’t a prescribed benzo, it should remind us all that the combination of opioids plus benzos is dangerous,” he said.

In Maryland, some lawmakers have grown increasingly concerned about adulterants in the illicit drug supply. Earlier this year, Del. Jesse Pippy, a Frederick County Republican, introduced a bill to further restrict two other sedatives — animal tranquilizers — that are being mixed with fentanyl with increased frequency. The bill did not make it out of committee.

When fentanyl first became commonplace in Maryland, Pippy said the state and local jurisdictions weren’t prepared, which helped contribute to the increase in overdoses. Now that street drugs contain sedatives that naloxone cannot reverse the effects of, Pippy said he’s worried about being caught flat-footed again.

“I’m really hoping in the next legislative session that we take affirmative action to address it,” Pippy said. “It’s a big deal, I think the more research people do they’re going to realize ‘Holy cow, we have got to be all over this.’”

State health officials referred questions to the city health department, which didn’t respond to requests for comment. Mayor Brandon Scott’s office also did not respond to a request for comment.

The Baltimore Police Department continues to investigate the origin of last week’s mass overdose incident. No arrests have been publicly announced; a spokesperson did not return a request for comment.