Nektar reports positive top-line results from HAP study of NKTR-181 for chronic pain


US-based biopharmaceutical firm Nektar Therapeutics has reported positive top-line results from an oral human abuse potential (HAP) study of its opioid analgesic, NKTR-181, for chronic pain.

NKTR-181 is a new chemical entity (NCE) full mu-opioid agonist molecule currently being developed to deliver potent pain relief without causing abuse and addiction via strategic alteration of brain-entry kinetics.

According to the results, NKTR-181 demonstrated significantly less abuse potential when compared to a schedule II opioid, oxycodone.

The randomised, double-blind, placebo-controlled, six-sequence crossover HAP study compared the oral abuse potential of maximum analgesic or a therapeutic dose of 400mg and a supratherapeutic dose of NKTR-181 at 1,200mg with common therapeutic oxycodone doses.

"It is clear from our new study results that NKTR-181 is highly differentiated in this respect from oxycodone, which is a choice drug of abuse."

Trial subjects included healthy non-dependent recreational drug users who were experienced in the oral abuse of opioids and could detect drug effects relevant for abuse risk assessment.

Nektar Therapeutics senior vice-president and chief medical officer Ivan Gergel said: “It is clear from our new study results that NKTR-181 is highly differentiated in this respect from oxycodone, which is a choice drug of abuse. 

“Furthermore, and critically important in the context of this public health emergency, NKTR-181's less rewarding properties and strong analgesia are inherent to its novel molecular structure and independent of any abuse-deterrent formulation.”

In each of the trial’s six test sequences, patients were administered with a single dose of 400mg, 600mg or 1,200mg of NKTR-181, or 40mg or 60mg of oxycodone with a five-day washout period between each treatment.

Effects predictive of abuse potential with opioids for all doses were monitored during the trial and aimed to identify a relative peak drug liking score difference between 60mg of oxycodone and 1,200mg of NKTR-181.