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Grünenthal announced today that the company successfully concluded a
Phase I trial evaluating the safety and tolerability of its proprietary
NOP agonist. In the trial, which involved 113 healthy participants, the
compound was demonstrated to be safe and well tolerated, with no
dose-dependent adverse event pattern observed.[1] Grünenthal is now
planning to progress its NOP agonist into a Phase II trial that aims to
enrol 400 US-based patients undergoing bunionectomy – a well-established
model for evaluating the efficacy and safety of a compound as a
treatment for acute pain. The trial will commence later this year with
results expected in the second half of 2027.
Through its specific selectivity for the nociceptin receptor,
Grünenthal's NOP agonist features a unique mechanism of action for the
treatment of acute and chronic pain and may present a first-in-class
therapy option. The compound has the potential to deliver robust pain
relief in a broad range of conditions without the side effects commonly
associated with opioids. During the Phase I trial, no such adverse
events, including somnolence, constipation or respiratory depression, or
events suggesting any abuse liability potential were observed.
"We are excited about the successful completion of our Phase I clinical
trial and double down on our efforts to bring the compound to patients",
says Uli Brödl, MD, Chief Scientific Officer at Grünenthal. "With
selective nociceptin receptor activation, Grünenthal hopes to introduce
a new mechanism of action into the pain treatment landscape and provide
patients with a much-needed alternative therapy option."
About Bunionectomy
Bunionectomy is the surgical procedure for removing a bunion, an
enlargement of bone and soft tissue that develops on the side of the
foot, which most commonly occurs in the joint at the base of the big
toe: the big toe progressively angles outwards towards the smaller toes,
creating a bony bump (hallux valgus deformity). Bunions may be caused by
hereditary factors, inflammatory arthritic conditions, or through
wearing poorly fitting or pointed shoes that constrict the toes.[2]
Bunionectomy is accepted by regulatory authorities as a postoperative
hard (bony) tissue pain model in which the analgesic effect of an
investigational compound may be evaluated as a treatment for acute
pain.[3]
About the NOP Receptor
The Nociceptin/Orphanin Receptor (NOP) is a G protein-coupled receptor
whose natural ligand is the 17-amino-acid neuropeptide nociceptin
(N/OFQ).[4] NOP agonists have been shown to act as potent analgesics
without the potential for abuse liability in pre-clinical models.[5]
Although the NOP receptor shares some sequence identity (~60%) with the
opioid receptors μ-OP (MOP), κ-OP (KOP), and δ-OP (DOP), it possesses
little or no affinity for opioid peptides or morphine-like compounds.
Likewise, opioid receptors possess little affinity towards NOP's
endogenous ligand nociceptin.[6]
About Grünenthal
Grünenthal is a global leader in pain management and related diseases.
As a science-based, fully integrated pharmaceutical company, we have a
long track record of bringing innovative treatments and state-of-the-art
technologies to patients worldwide. Our purpose is to change lives for
the better – and innovation is our passion. We focus all our activities
and efforts on working towards our vision of a World Free of Pain.
Grünenthal is headquartered in Aachen, Germany, and has affiliates in 28
countries across Europe, Latin America, and the U.S. Our products are
available in approx. 100 countries. In 2025, Grünenthal employed around
4,100 people and achieved revenues of €1.8 billion. More information: www.grunenthal.com
and follow us on LinkedIn & Instagram For further information, please
contact: Christopher Jansen, Global Communications at Grünenthal, [email protected]
[1] Grünenthal Data on File
[2] my.clevelandclinic.org (accessed 23 June 2026)
[3] Singla et al. Bunionectomy as an Acute Postoperative Pain Model:
Overview of Common Experimental Methods, and Insights from Past Clinical
Trials. Journal of Pain Research 2024; 17: 4399-4420.
[4] Henderson G, McKnight AT. The orphan opioid receptor and its
endogenous ligand-- nociceptin/orphanin FQ. Trends in Pharmacological
Sciences 1997; 18 (8): 293–300.
[5] Lin AP, Ko MC. The therapeutic potential of nociceptin/orphanin FQ
receptor agonists as analgesics without abuse liability. ACS Chem
Neurosci. 2013; 4(2): 214-24.
[6] Butour et al. Recognition and activation of the opioid receptor-like
ORL 1 receptor by nociceptin, nociceptin analogs and opioids. European
Journal of Pharmacology 1997; 321(1): 97–103.
For further information, please contact:
Christopher Jansen, Global Communications at Grünenthal, [email protected]
Distributed by Pressat
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