KINETICfinder® provides reliable binding kinetics of mu-opioid receptor antagonists and agonists

Exploiting  the temporal dimension of GPCR signalling

Drug binding and signaling at G-Protein-Coupled Receptors (GPCRs) are dynamic events that vary dramatically over time1-7. Many reports link the kinetics of drug binding and unbinding to GPCRs to the effectiveness and safety of many drugs8-17. Profiling the drug binding kinetics with KINETICfinder® is key to:

  • Optimize in vivo receptor occupancy, ensuring therapeutic efficacy and avoiding drug-induced side effects.
  • Understand the impact of binding kinetics on the sustained signaling from internalized receptors.
  • Exploit ligand bias.
  • Design conformation-specific drugs.

KINETICfinder® provides reliable binding kinetics of mu-opioid receptor antagonists and agonists

Opioid drugs are the gold standard for the management of pain, but their use is limited by dangerous side effects. All clinically available opioid analgesics bind to and activate the mu-opioid receptor, a G-protein-coupled receptor, to produce analgesia.

In this study, we determine the binding kinetics of the clinically relevant mu-opioid receptor buprenorphine and naloxone using KINETICfinder® in living cells.

  • We employ intact cells to preserve the intracellular proteins that interact with GPCRs and may stabilise different conformations of the receptors, affecting the binding kinetics of the ligands.
  • The high and sustained stability of our GPCR assays guarantees superior quality results, enabling kinetic data to be interpreted with confidence (Fig. 2).

Figure 1. Binding kinetic profile of buprenorphine and naloxone against mu-opioid receptor using KINETICfinder®.

  • The affinity and binding kinetic values obtained for the mu-opioid receptor agonists and antagonists with KINETICfinder® are in line with previous studies (Fig. 2)18-21.
  • Buprenorphine is a FDA-approved partial agonist for chronic pain and opioid dependence.
  • Buprenorphine has high-affinity binding to the mu-opioid receptors (0.2 nM) and slow-dissociation kinetics (2.0×10-4 s-1). In this way, it differs from other full-opioid agonists like morphine and fentanyl, allowing respiratory depressant effect to be milder.
  • Naloxone is a FDA-approved antagonist for use in an opioid overdose and the reversal of respiratory depression associated with opioid use. It has 13-fold lower affinity binding (2.3 nM) for the mu-opioid receptors and rapid-dissociation kinetics (2.4×10-2 s-1).

Figure 2. Graph: Signal-to-background and Z-values were calculated based on 32 control wells over 4 hours. Table: Association rate (kon), dissociation rate (koff), residence time (τ), half-life time (T1/2) and affinity values obtained with KINETICfinder® and IC50 and T1/2 values from literature.


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