Eli Lilly and Co on Tuesday said it and partner Pfizer Inc aim to seek approval by 2018 for a new type of pain drug that could be an alternative to opioids for osteoarthritis, chronic back pain and cancer pain.

The Indianapolis drugmaker said tanezumab, given by injection every eight weeks, could be a far more effective and appropriate alternative for chronic pain than opioids, without their abuse potential.

"Opioids cause addiction and (overdoses) that are killing more people than traffic accidents," Jan Lundberg, Lilly's research chief, said in an interview. "If our medicine proves effective and safe, that would be a huge opportunity."

Pfizer and Lilly, in a $1.8 billion deal, agreed in 2013 to jointly develop and sell tanezumab for several pain-related conditions, with the companies equally sharing development expenses and future sales.

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Tanezumab has proven in large trials conducted by Pfizer more effective than oxycodone, a widely used opioid, and naproxen, the active ingredient of over-the-counter painkiller Aleve.

It blocks Nerve Growth Factor (NGF), a protein involved in growth of nerve cells. U.S. regulators in 2012 put a hold on trials of medicines targeting the protein due to concerns they could worsen osteoarthritis in a small percentage of patients.

But the agency lifted the hold last year after new data suggested such risk could be greatly reduced by using lower drug doses and taking other precautions.

Opioids caused 18,893 overdose deaths in the United States in 2014, according to the American Society of Addiction Medicine. Another 10,574 overdose deaths were due to heroin, it said, an illegal opioid to which abusers of prescription opioids often turn because of its far-cheaper price.

Andrew Ahn, chief scientific officer of pain research at Lilly, said opioids are effective against acute pain. But he said they have limited and decreasing effectiveness against chronic pain. Even so, he noted many doctors prescribe opioids for patients with long-term back pain, osteoarthritis and cancer.

"So they chase relief with higher and higher doses until they stop breathing," he said on the sidelines of a company meeting in New York with industry analysts and fund managers.

Although well tolerated so far, some patients taking tanezumab have developed swelling of the extremities and other side effects.

Morningstar analyst Damien Conover said tanezumab, if approved, could generate annual sales of $1 billion. But he said the earlier FDA safety concerns have dampened enthusiasm for the emerging new class of drugs.