FDA Grants Fast Track Designation for Investigational Opioid Analgesic

The FDA granted fast track designation for NKTR-181 (Nektar), a first-in-class opioid analgesic, designed to relieve pain while significantly lowering the risk for abuse compared  with oxycodone, according to a press release from the manufacturer.

The investigational drug is believed to work by creating a blood-brain barrier, allowing a slower rate of entry into the brain. This design is thought to decrease the dopamine response—a key factor in euphoria associated with opioids. 

The SUMMIT-07 study explored the effects of twice-daily doses of NKTR-181 tablets to placebo on 600 patients new to opioid therapy with moderate to severe chronic low back pain. Patients were first titrated from 100 mg to 400 mg twice daily before entering the placebo phase for 12 weeks.

Researchers determined average pain scores dropped by 65%, from a score of 6.73 during the initial screening to 2.32 at the time patients were randomly assigned to either NKTR-181 or placebo. 

Overall, 83% of patients completed the 12-week, double-blind, randomly assigned, treatment period. Average pain scores increased significantly more in the placebo treatment phase compared with the NKTR-181 phase at week 12 from baseline (P < .0001).

The most common adverse events include nausea and constipation.

The FDA determined that results from this study and others suggest NKTR-181 has a lower risk for abuse compared with oxycodone. Further studies are warranted to determine
the drug’s effects at higher doses, as well as its potential risk via intranasal and inhaled
administration. —Samantha Costa