PPL-138

**PPL-138** is a bifunctional opioid receptor ligand developed as a naltrexone analog with high affinity across the opioid receptor family. It acts as a partial agonist at nociceptin opioid peptide (**NOP**) and mu-opioid (**MOP**) receptors, and an antagonist at kappa and delta receptors, providing potent antinociceptive effects with reduced side effects compared to traditional opioids, such as low abuse liability, no respiratory depression, and no tolerance development after chronic administration. Phoenix PharmaLabs owns the intellectual property and is advancing it through preclinical studies toward clinical trials, primarily for **pain** management, with demonstrated efficacy in reducing cocaine self-administration, reinstatement of cocaine seeking, PTSD-like symptoms (anxiety, pain), and alcohol consumption in stress-susceptible rat models via intraperitoneal or intravenous routes.[1][2][7][8]

Other names

Phoenix PharmaLabs-NOP receptor25+ Nociceptin compounds