Shawn Flynn, a student in the Physiology and Pharmacology discipline of the Integrated Biomedical Sciences Ph.D. program has just published a first-author paper in Drug and Alcohol Dependence. The paper, “Discriminative stimulus effects of carfentanil in rats discriminating fentanyl: Differential antagonism by naltrexone” looks at carfentanil, a derivative of fentanyl that is believed to be over 1000 times more potent than heroin. He is in the lab of Dr. Charles France.

Flynn explained that the number of opioid overdose deaths in the United States continues to rise each year.

“In recent years there have been dramatic increases in the number of opioid overdose deaths involving synthetic opioids such as fentanyl,” he said. “These drugs [like carfentanil] are particularly dangerous because even extremely small amounts of the drug can cause grave consequences.”

This paper compares the ability of naltrexone, an opioid antagonist, to block the effects of three different opioid drugs: heroin, fentanyl, and carfentanil.

“We find that that the ability of naltrexone to block the effects of carfentanil is diminished compared with heroin and fentanyl, though the reason for this discrepancy is unclear,” Flynn said.

He explained that the next steps for this project are to determine whether this difference also exists when measuring clinically relevant effects of opioids such as respiration, and to start to figure out what mechanism might underlie the difference that were observed.

“These findings will end up providing important information that will improve the treatment of opioid overdoses involving carfentanil, and the development of more effective compounds for reversing opioid overdose,” he said.

A visual comparison of the lethal dose of each of the drugs studied in the paper. Photo Credit: NH Register

Flynn would like to thank the France lab and his colleagues.

“It’s exciting to have published my first paper since joining the France lab here at UT Health San Antonio. I’m thankful to my mentor as well as the rest of my lab for their help and guidance.”

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In Press is a section in The Pipette Gazette that highlights publications by students. To read more In Press articles, click here.