CB2 receptor activation reduced fentanyl-induced respiratory depression in mice | Research

The takeaway

The CB2 cannabinoid receptor agonist LY2828360 attenuated fentanyl-induced respiratory depression in normal mice but not in CB2 knockout mice, suggesting a CB2-mediated protective effect.

Overdose prevention researchers, pharmacologists, pain medicine specialists, and harm reduction advocates.

CB2 agonist attenuated fentanyl respiratory depression in wild-type but not knockout mice

What the researchers found

Co-administration of LY2828360 (3 mg/kg) with fentanyl (0.2 mg/kg) attenuated respiratory depression in wild-type mice but not CB2 knockout mice, confirming the effect was CB2-mediated. LY2828360 alone had no effect on respiratory parameters in either genotype.

Why it matters

Opioid-induced respiratory depression is the primary cause of overdose deaths. A cannabinoid compound that reduces this risk without itself affecting breathing could be a breakthrough in harm reduction.

The numbers in context

Fentanyl doses: 0.1 and 0.2 mg/kg. LY2828360 dose: 3 mg/kg. Higher fentanyl dose produced greater respiratory suppression. CB2 agonist attenuated depression in WT but not CB2KO mice.

How the study worked

Whole-body plethysmography in wild-type and CB2 knockout mice. Measured minute ventilation, respiratory frequency, and tidal volume after fentanyl alone vs. fentanyl + LY2828360 co-administration.

What this study cannot tell us

Animal study in mice. Unknown whether CB2 agonists would have the same effect in humans. Single dose combination tested. Long-term effects unknown.

How to read the evidence

Well-designed animal study with knockout confirmation of mechanism, but requires human translation.

When this study was published

Published in 2021.

The bigger picture

With fentanyl responsible for more overdose deaths than any other opioid, finding compounds that specifically counteract its respiratory depression while potentially enhancing pain relief represents a promising harm reduction strategy.

Questions still open

Would CB2 agonists maintain opioid pain relief while reducing respiratory depression in humans? Could this approach be developed into a co-formulation with opioids?

Common questions

Can cannabinoids prevent opioid overdose?

In mice, a CB2 cannabinoid receptor agonist reduced fentanyl-induced respiratory depression, the primary cause of overdose death. The compound itself did not affect breathing.

How was the CB2 mechanism confirmed?

The protective effect occurred in normal mice but disappeared in mice genetically lacking CB2 receptors, confirming the effect was specifically mediated through CB2.

Read the original research

Cannabinoid CB2 Receptor Activation Attenuates Fentanyl-Induced Respiratory Depression.

Cannabis and cannabinoid research, 6(5), 389-400

View on PubMed ↗Publisher’s paper ↗

Citation

Zavala, Carmen A; Thomaz, Ana C; Iyer, Vishakh; Mackie, Ken; Hohmann, Andrea G. (2021). Cannabinoid CB2 Receptor Activation Attenuates Fentanyl-Induced Respiratory Depression.. Cannabis and cannabinoid research, 6(5), 389-400. https://doi.org/10.1089/can.2020.0059