Nektar Therapeutics (NASDAQ: NKTR) has enrolled the first patient in a Phase II clinical study of a new opioid analgesic that is designed to enter the brain slowly, reducing the potential for the drug to be abused or misused. The drug, called NKTR-181, has been designated by the Food and Drug Administration for “Fast Track” development for the treatment of moderate to severe chronic pain.
NKTR-181 crosses the blood-brain barrier at a rate about ten times slower than oxycodone and other opioids. Because it has a slower rate of entry into the brain, Nektar says the drug has the potential to reduce the euphoria that leads to abuse and addiction. Side effects such as respiratory depression and sedation may also be reduced.
“NKTR-181 has the potential to transform the treatment of chronic pain by using a molecular approach to reduce the risk of traditional opioid therapy while preserving its analgesic benefit,” said Robert Medve, MD, Senior Vice President and Chief Medical Officer of Nektar.
Earlier this year, the company completed a Phase I clinical study of NKTR-181 involving more than 180 patients, which showed it controlled pain with no evidence of drug tolerance after 8 days of twice-daily dosing.
The Phase II study will involve about 200 patients with moderate to severe pain from osteoarthritis of the knee who are not getting adequate pain relief from non-opioid medications. Patients in the study will receive either NKTR-181 or a placebo twice daily for up to 25 days. In addition to pain levels, the patients’ quality of life, sleep and motor activities will also be assessed.
NKTR-181 was created using Nektar’s proprietary small molecule polymer conjugate technology. As a new molecular structure, NTKR-181 does not need to be reformulated, a method used by some pharmaceutical companies to discourage drug abuse. In 2010, Purdue Pharma changed the formula for its widely abused painkiller OxyContin, making the drug harder to crush or dissolve.
As part of its Phase II development of NKTR-181, Nektar is also planning a separate human abuse liability study. The study will measure “liking” scores for NKTR-181 when compared to another opioid in approximately 20 recreational drug users.