(Reuters) – Independent advisers to the U.S. Food and Drug Administration on Tuesday unanimously voted against Nektar Therapeutics’ opioid painkiller for adults with chronic low back pain, sending the drug developer’s shares down 12% in extended trading. The panel voted 27-0 against approval of the oral pill, NKTR-181, flagging concerns over the chances of misuse or abuse, the lack of data to determine the possible abuse when snorted or injected as well as the potential for liver toxicity. By reducing the rate at which the drug enters the brain, Nektar said it aims to relieve pain without triggering the euphoric effect of opioids that could lead to abuse and addiction. The company has said if snorted or injected, the rate of the drug’s entry into the brain would be similar to when the pills are taken orally. “Just too much (data) was missing… I couldn’t say the benefits outweighed the risks,” said panel member Lee Hoffer from Case Western Reserve University in Cleveland, Ohio. As the United States grapples with the problem of opioid addiction that has claimed the lives of over 47,000 people, the FDA has been increasingly reluctant to greenlight new opioid-based drugs. Compared to commercially available opioids, the more gradual effects of NKTR-181 may make it less attractive as a drug of abuse for people seeking a rapid onset of a “high”, according to the company. Low back pain is generally treated with anti-inflammatory drugs, acetaminophen and opioids based on the severity of pain. “I voted no even though I liked the idea of what they are trying to do. The data, I don’t think at the end of the day was sufficient from the standpoint of efficacy and safety,” said panel member Dr. Sherif Zaafran, vice chairman of the clinical governance board at U.S. Anesthesia Partners. The FDA is expected to make a final decision on the treatment’s approval this year. While the agency is not bound to follow the recommendation of its advisory panel, it usually does.