When the victims were struggling to breathe and the medics were working over them, there was no time to think about the journey of a synthetic drug as it traveled from the trash bin of a Connecticut pharmaceutical giant to clandestine overseas labs to the center of the recent mass overdose on the New Haven Green.

But a whole group of people, from recovery counselors and doctors, to lawmakers and law enforcers, are troubled by the presence of the iterations of Fubinaca and similar synthetic compounds in cities with populations drawn to their cheap price, growing availability, and the ease in which the drugs are mixed with the potpourri-like synthetic K2 and smoked in what looks like its less insidious sister, a marijuana cigarette.

The route that versions of the substance took to surface on a Brooklyn sidewalk in July 2016 where it knocked down 33 people, or the New Haven Green, where it led to 114 ambulance transports, or in Texas, or in Pennsylvania, is in itself a demonstration of the daunting challenges they present to law enforcement and to health care.

Ab-Fubinaca was formed in 2009 in a lab at Pfizer Pharmaceutical, the massive drug company with an extensive research and laboratory operation in Groton.

Pfizer scientists thought they may have had a fix on a new drug to relieve pain and suffering in cancer patients, oncology being one of the fields that the drug giant is focusing on, along with vaccines, immunotherapy and gene therapy.

The company applied for a patent, outlining in the application form the chemical “entity” — the structure of, and formula for the compound they hoped to produce. The scientists conducted laboratory experiments.

It wasn’t working.

In short order, the research was halted and the drug was abandoned by Pfizer even before it was tested on humans, spokeswoman Sally Beatty said. These starts and stops aren’t unusual in a research lab.

“It’s the way science works,” Beatty said.

All work on the drug was stopped before the application had a chance to advance in the U.S. Patent Office, and a patent was never issued. Pfizer would receive a notice from the office in 2013 that the application had been abandoned.

But a blueprint was out in the world. There is enough information in these drug-patent applications, which are in the public domain, for other scientists in other labs to continue the development. This information sharing is also the way science works, and most of the time, it is for the good.

But not always.

“It’s a balancing act,” said Rod Marriott, drug-control chief for the Connecticut Department of Consumer Protection. “Public information versus the harm the information might cause to the public.”

Nefarious scientists in clandestine labs are forever looking for abandoned research drugs they can exploit, especially in the area of synthetic narcotics.

Consider the plight of John W. Huffman, a highly regarded professor and organic chemist at Clemson University. He and his team blended THC, the ingredient in marijuana that makes the smoker high, with synthetic “cannabinoid” compounds to research the effect on receptors in the human nervous system. It didn’t take long for people in Germany to start mixing the new compounds with “Spice,” their version of K2, to produce a dangerously potent high.

Born with good intent the “JWH” series of synthetic compounds is now illegal in the U.S., classified as a controlled substance. As for Huffman, he has served as an expert witness and has cooperated with law enforcement.

In Connecticut, three of the JWH compounds are expressly banned and designated as “schedule 1 drugs” — with no medical purpose.

Nationally, AB-Fubinaca is also a designated schedule 1 controlled substance. Among the effects of the group of related Fubinaca compounds are drowsiness, lightheadedness, and fast or irregular heartbeat. The more severe reactions include psychosis, seizures, kidney injury, hyperthermia and death.

But the various Fubinaca compounds have long been stars in the black-market labs of China and other locations in Asia.

Sen. Richard Blumenthal of Connecticut, speaking after the New Haven outbreak, said K2 laced with versions of Fubinaca and other compounds flow across the Mexican border, and is also available cheap on the internet.

“China is the enemy when it comes to synthetics,” Blumenthal said. “It’s not happening without the tolerance” of the Chinese government.

And with the drugs now prevalent in the U.S., “we’re not going to arrest our way out of the problem,” Blumenthal said.

Since there were no laboratory trials for the Fubinaca group, overdose victims have served as the test groups.

After the Brooklyn outbreak in 2016, Roy Gerona, a research scientist at the University of California, San Francisco, and several colleagues tested blood and urine samples of eight of the overdose victims, most of whom had displayed “zombie-like” symptoms after smoking synthetic cannabis.

Writing in the New England Journal of Medicine in January 2017, Gerona and his co-authors reported that AMB-Fubinaca, another iteration of the Pfizer research drug, was identified in all eight patients. It had acted like a “strong depressant” that accounted for the zombie-like behavior, and was “an example of the emerging class of ultrapotent” synthetic drugs that pose a public-health concern .

These synthetics, the researchers wrote, “shifted from research tools to drugs of abuse in 2008.” That’s when samples of K2, or “Spice” as it is known in Europe, were first found to contain one or more of the “JWH” compounds.

“Since then, new synthetic cannabinoids have been developed in clandestine laboratories in China and South Asia and distributed by ‘dark net’ retailers, street drug dealers, and organized crime groups as inexpensive alternatives” to cocaine and other traditional drugs of abuse,” the team wrote in the New England Journal.

And what makes reining in the synthetic menace so difficult for law enforcement and regulators is that one tiny change in the formula produces a whole new drug, noted Marriott, consumer protection’s drug-control chief.

“In the synthetic world, there are many iterations of the same drug — Fubinaca may not be Fubinaca anymore, simply because small components were changed,” said Marriott.

He said these drugs can defy urine screens and other drug tests, and developing new tests that can keep up with the latest synthetic concoctions is expensive and challenging, Marriott said.

The rapid changes “make it hard to track down the source or write laws that encompass all of the compounds,” he said.