(Reuters) – A non-opioid painkiller developed by Pfizer Inc and Eli Lilly and Co succeeded in reducing chronic low back pain when used in a stronger dose, results from a late-stage study showed on Tuesday.

But a lower dose of the drug, tanezumab, failed to alleviate pain when compared with a placebo, the companies said in a statement.

The drug was being tested in patients who had already used three different classes of painkillers but had not experienced enough relief or were intolerant to those treatments.

Tanezumab belongs to a category of pain medications that target the nerve growth factor, a protein involved in the growth of nerve cells.

U.S. health regulators have been encouraging the development of such pain medicines rather than opioids, as the United States faces an epidemic of opioid use and abuse.

Chronic low back pain affects an estimated 33 million Americans and is a leading cause of disability, Pfizer and Lilly said. Treatment often requires painkillers such as codeine, in cases where over-the-counter medication does not help.

Last year, the two companies reported positive results from a late-stage study testing tanezumab in patients with osteoarthritis pain of the knee or hip.

(Reporting by Manas Mishra in Bengaluru; Editing by Sai Sachin Ravikumar)

tagreuters.com2019binary_LYNXNPEF1I0UV-VIEWIMAGE