Nektar Therapeutics (NKTR) - Get Report Tuesday morning released results from a new study showing its candidate to treat chronic pain carries significantly less abuse potential than oxycodone. 

Nektar shares were up 94 cents, or 4.55%, to $21.60 Tuesday, July 18.

Nektar, which released results from a Phase 3 study in March that showed the drug met its endpoints in the treatment of chronic pain, announced positive topline results from an oral Human Abuse Potential (HAP) study of NKTR-181.

NKTR-181 is the first full mu-opioid agonist molecule designed to provide potent pain relief without the high levels of euphoria that can lead to abuse and addiction with standard opioids.

In an interview, Nektar's chief science officer, Steve Doberstein, said that unlike other recent efforts to make opioids less susceptible to abuse, NKTR-181 was designed to offer less euphoria than other painkillers on the market. Efforts to make existing painkillers less likely to be abused have focused on making the drugs harder to snort or inject but little can be done to make the molecules themselves less likely to cause an addictive high.

NKTR-181 relies on its inherent molecular properties to get into the brain more slowly.

The U.S. Food and Drug Administration (FDA) has granted the NKTR-181 Fast Track designation for the treatment of moderate to severe chronic pain. Nektar is wrapping up safety testing on NKTR-181 and will meet with FDA officials later this year to prepare for the company's filing of a New Drug Application to market the drug.

The addiction study was designed to assess the oral abuse potential of NKTR-181 at its maximum analgesic or therapeutic dose, 400 mg, and at a dose three times to 12 times greater than its analgesic dose range of 100 mg to 400 mg compared to common therapeutic doses of a oxycodone.

"Today's opioid abuse epidemic has created a pressing need for a better pain medicine that does not possess the euphorigenic qualities of conventional opioids," said Dr. Ivan Gergel, chief medical officer of Nektar, in a prepared statement. "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."

Nektar officials said that the addictiveness of opioids currently on the market not only fuels abuse of painkillers and illegal drugs but harms suffers of chronic pains who often under-medicate and endure pain rather than increase their odds of addiction by taking full dosages.

"Many patients do not receive adequate pain relief because they fear taking conventional opioids, including abuse-deterrent formulations, because of their potential for abuse and addiction. We believe NKTR-181 is a transformational pain medicine that should significantly advance the treatment of chronic pain and could be a fundamental building block in the fight against prescription opioid abuse," Gergel said. "We are committed to bringing this new pain treatment to patients and physicians as quickly as possible."

Opioids act on specific receptors in the brain to provide pain relief, but they also target the dopamine reward system in the brain to produce euphoria and other psychoactive effects, which leads to addiction and abuse. NKTR-181 was designed to delay the euphoric and other psychoactive effects to avoid the "rush" that dug abusers seek.