Opioid overdose medications may be more effective in women, according to new PET imaging study
Using whole-body PET imaging, researchers recently determined that drugs developed to treat overdoses may be more effective in certain individuals.
Specifically, experts observed imaging findings suggesting that drugs like Narcan may be more beneficial in women. PET scans revealed that μ-opioid receptor (MOR) availability in women was more markedly reduced after administration compared to men, indicating higher efficacy. Experts involved in the study suggested that their findings could bring about more effective treatments for opioid use disorders.
“A better understanding of the interactions of opioid drugs with the MOR could help to elucidate the etiology, prevention, and treatment of opioid use disorder,” Jacob Dubroff, MD, PhD, associate professor of radiology in the division of nuclear medicine imaging & therapy at Perelman School of Medicine at the University of Pennsylvania in Philadelphia, noted in a news release. “MORs have a high affinity for both endogenous opioids such as β-endorphins and exogenous opioids such as fentanyl. They mediate pain and reward and have been implicated in the pathophysiology of opioid, cocaine, and other substance use disorders.”
The central nervous system, peripheral organs and immune system all express MORs, making them a suitable target for drugs that treat opioid disorders. Dubroff and colleagues sought to understand how the administration these medications affect individuals on a physiological level.
Using a MOR-selective radioligand, [11C]carfentanil, the team measured the whole-body distribution of MORs in a group of 13 healthy participants, taking note of sex differences at baseline and after taking the medication.
During the two imaging sessions, researchers calculated brain distribution and peripheral organ distribution volume ratios using the occipital cortex and visual cortex (for the brain) and the descending aorta and biceps/triceps (for peripheral distribution) as reference regions. Through this, the team noted a naloxone-induced reduction in MOR availability in 40-50% of brain regions know to express high levels of MORs in women. Both the descending aorta and biceps/triceps measurements indicated greater blocking effects in women as well.
The team suggested their findings could be beneficial in future drug development targeting opioid disorders.
“This research is significant because it suggests that there may be sex-based differences in how men and women respond to opioid overdose treatments,” Dubroff said. “Additionally, we showed how regions outside the brain can be used to help measure radiotracer binding in the brain. This strategy could be applied to other radiotracers used for PET brain imaging and boost the development of new ones.”
Read more about the findings in The Journal of Nuclear Medicine.
In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.