Bruce Hammock has spent a 50-year career studying insects. The professor probably wouldn't be the Ph.D. considered most likely to shake up the multibillion-dollar prescription painkiller market.

Nonetheless, he has developed a medication for chronic pain that he said has proved effective and nonaddictive in animal trials. Could his discovery put an end to the toll caused by opioid drugs that racked up $24.5 billion in sales in 2018?

Pharmaceutical researcher William Schmidt said he found Hammock's novel drug candidate so promising that he volunteered to work at no charge until they can move the technology out of the university and secure financing for Hammock's company, eicOsis.

"We have a drug candidate lacking the side effects of both opioids and nonsteroidal anti-inflammatory drugs that can potentially lead to an entirely new way to treat chronic pain," Schmidt said.

Hammock and Schmidt said they expect to launch human trials by August or September. The clinical studies have received more than $4 million in support from the National Institutes of Health, they said, and $5 million from Open Philanthropy Foundation.

"Chronic pain is an enormous emotional and economic burden for more than 100 million people in the United States alone," said Hammock of the University of California, Davis.

He traces the genesis of his drug to the 1970s when he was trying to keep brown moths from consuming as much as half of the world's food supply.

His lab discovered that an enzyme facilitated the moth's transformation from corn earworm to winged insect and if they could remove that enzyme, the caterpillar would die before it could breed. It turned out that there were more cost-effective ways to control brown moths, Hammock said, but his team's discovery proved valuable in controlling flea and mosquito development.

His team then asked: What role does this enzyme play in humans? As it turned out, it played a role in how much pain humans experience.

That finding led them to a group of compounds that naturally occur in the body and that reduce pain. Typically, these compounds are rapidly broken down in the body, Hammock said, but his team figured out a way to block their destruction.

The compounds do not prevent the warning of pain, Hammock said, so people will know if they put their hands in hot water, but the compounds can keep people from feeling pain that is out of proportion to the degree of the injury.