Development and in Vitro Characterization of a Novel Bifunctional μ-Agonist/δ-Antagonist Opioid Tetrapeptide

Medical School and College of Pharmacy, Department of Pharmacology, University of Michigan, Ann Arbor 48109, USA.
ACS Chemical Biology (Impact Factor: 5.36). 09/2011; 6(12):1375-81. DOI: 10.1021/cb200263q
Source: PubMed

ABSTRACT The development of tolerance to and dependence on opioid analgesics greatly reduces their long-term usefulness. Previous studies have demonstrated that co-administration of a μ-opioid receptor (MOR) agonist and δ-opioid receptor (DOR) antagonist can decrease MOR agonist-induced tolerance and dependence development after chronic exposure. Clinically, a single ligand displaying multiple efficacies (e.g., MOR agonism concurrently with DOR antagonism) would be of increased value over two drugs administered simultaneously. Guided by modeling of receptor-ligand complexes we have developed a series of potent non-selective opioid tetrapeptides that have differing efficacy at MOR and DOR. In particular, our lead peptide (KSK-103) binds with equal affinity to MOR and DOR but acts as a MOR agonist with similar efficacy but greater potency than morphine and a DOR antagonist in cellular assays measuring both G protein stimulation and adenylyl cyclase inhibition.


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May 21, 2014