(Removes reference to tramadol as a non-opioid in headline, paragraph 1, 2)
(Reuters) -Avenue Therapeutics Inc said on Monday the U.S. Food and Drug Administration (FDA) declined to approve its intravenous formulation of painkiller tramadol for a second time, sending its shares tumbling about 38%.
The health regulator in October declined to approve the intravenous formulation of the painkiller, stating it was not safe for the intended population.
The agency said on Monday the delayed and unpredictable onset of analgesia - relief from pain - with intravenous (IV) tramadol did not support its benefit as a monotherapy to treat patients with acute pain.
There was also insufficient data to support that IV tramadol was safe and effective in combination with other drugs, FDA said in its decision that came in more than two months after the scheduled date of April 12.
H.C. Wainwright analyst Joseph Pantginis, however, says that IV tramadol could still have a path forward.
The FDA did not mention any "chemistry, manufacturing and controls (CMC)" issues in its complete response letter, Avenue said, adding that it disagreed with the agency's decision and would continue to seek regulatory approval for IV tramadol.
Tramadol was approved in the United States in 1995 as a non-controlled analgesic, under the trade name of Ultram, to be sold by drugmaker Johnson & Johnson.
(Reporting by Trisha Roy in Bengaluru; Editing by Rashmi Aich and Shinjini Ganguli)