Hybrid Peptides Combining Opioid Pain Relief With Neurokinin Receptor Blocking | Research

The takeaway

New hybrid peptidomimetics combining dual opioid agonism with NK2/NK3 neurokinin receptor antagonism achieved nanomolar binding at all targets, offering a multi-target approach to pain relief with potentially fewer side effects.

Nanomolar at 4 receptors
Three hybrid compounds achieved nanomolar binding at mu-opioid, delta-opioid, NK2, and NK3 receptors simultaneously — a first for this receptor combination

What the researchers found

Three hybrid compounds (SBL-OPNK-5, -7, -9) bearing the KGOP01 scaffold achieved nanomolar μ-opioid receptor affinity, slightly reduced δ-opioid receptor affinity, and (sub)nanomolar NK2 and NK3 binding — the first designed multi-ligands targeting these receptor combinations.

Why it matters

Multi-target peptide drugs could provide effective pain relief with fewer opioid side effects by simultaneously engaging pain-suppressing opioid pathways and blocking pain-amplifying neurokinin pathways.

The numbers in context

3 successful hybrids (SBL-OPNK-5/7/9); nanomolar MOR affinity; (sub)nanomolar NK2/NK3; KGOP01 scaffold; first opioid-NK2/NK3 DMLs

How the study worked

Medicinal chemistry study. Peptidic and pseudo-peptidic NK2/NK3 ligands covalently linked to opioid pharmacophores (Dmt-DALDA and KGOP01). Opioid and neurokinin receptor binding assays performed.

Who was studied

In vitro receptor binding assays for opioid and neurokinin receptors

What this study cannot tell us

Binding assays only — no functional activity, animal testing, or pain relief measurement. In vitro receptor binding may not predict in vivo efficacy. Peptide stability and bioavailability not assessed.

How to read the evidence

Low evidence grade: in vitro binding data only. No functional, animal, or clinical testing performed. Represents early-stage drug design.

When this study was published

Published 2021. Multi-target opioid hybrids remain in early preclinical development.

The bigger picture

The opioid crisis drives urgent need for safer pain medications. Multi-target hybrid peptides represent a pharmacological strategy to maintain analgesic efficacy while potentially reducing addiction, tolerance, and other opioid side effects through complementary mechanisms.

Questions still open

Do these hybrid peptides produce effective pain relief with reduced opioid side effects in animal models?
Can the peptide bonds be modified for oral bioavailability?
Is NK2/NK3 antagonism more effective than NK1 antagonism for enhancing opioid analgesia?

Common questions

Why combine opioid and neurokinin-blocking activity in one drug?

Neurokinin receptors NK2 and NK3 amplify pain signals. Blocking them while activating opioid pain relief pathways could provide stronger analgesia with potentially lower opioid doses — reducing side effects like addiction, tolerance, and respiratory depression.

Could this replace current opioid painkillers?

Potentially, but these are very early-stage compounds. They have only been tested for receptor binding in the lab. Extensive animal testing, safety studies, and clinical trials would be needed before any could become a medication.

Read the original research

Harnessing the Anti-Nociceptive Potential of NK2 and NK3 Ligands in the Design of New Multifunctional μ/δ-Opioid Agonist-Neurokinin Antagonist Peptidomimetics.

Molecules (Basel, Switzerland), 26(17)

View on PubMed ↗Publisher’s paper ↗

Citation

Gadais, Charlène; Piekielna-Ciesielska, Justyna; De Neve, Jolien; Martin, Charlotte; Janecka, Anna; Ballet, Steven. (2021). Harnessing the Anti-Nociceptive Potential of NK2 and NK3 Ligands in the Design of New Multifunctional μ/δ-Opioid Agonist-Neurokinin Antagonist Peptidomimetics.. Molecules (Basel, Switzerland), 26(17). https://doi.org/10.3390/molecules26175406