Laura Ungar

@laura_ungar

Opioid painkillers have long been the gold standard for severe pain but come with a terrible dark side: They are the main culprits in a prescription drug abuse crisis that has killed thousands and spawned a resurgence of heroin in Kentucky and across the nation.

Now, scientists say they are closing in on creating medicines that can relieve severe, chronic pain without getting people hooked — raising hopes as well as skepticism among those fighting drug abuse.

Connecticut-based Cara Therapeutics recently released research showing its opioid drug is far less likely to cause patients to feel high than a "control" medicine considered to have a low potential for abuse.

Bob Twillman, deputy executive director of policy and advocacy for the American Academy of Pain Management, said he can envision Cara's drug — and others like it — eventually being prescribed instead of commonly abused painkillers such as oxycodone.

"If we can effectively replace these drugs," he said, "that would be a game changer."

Dr. Gavril Pasternak, an opioid researcher and expert at the Memorial Sloan-Kettering Cancer Center, said about a dozen drugs are being developed with the same goal — and they are getting closer than ever to market, although more research is needed.

The stakes are high: Drug overdoses were the leading cause of injury death in 2012, and Kentucky has one of the nation's worst prescription drug-abuse problems.

"Is (a non-addictive opioid) a possibility? Absolutely. And there are a lot of people devoting a lot of time and effort to it," said Pasternak, who is not associated with the Cara research. "It could be ready relatively soon. … In the short-term, it may be a major help."

Hope on horizon

Cara's compound, called CR845, works on different nerve-ending receptors than traditional treatments ("kappa" versus the usual "mu") and isn't believed to enter a patient's brain. Besides being non-addictive, drug makers say, it doesn't cause nausea, respiratory depression or other bad side effects. Pasternak said other opioids developed to be non-addictive had side effects such as seizures or hallucinations.

"We need safer medications," said Dr. Lynn Webster, lead investigator on the trials for the Cara drug and immediate past president of the American Academy of Pain Medicine. "They will not solve the problem of prescription drug abuse, but they will reduce overdose deaths."

The recent research tested an intravenous formulation of the drug for post-operative pain in the hospital, but Cara is also developing an oral version for chronic pain. Oral opioids are generally considered less addictive than IV opioids. Officials said they plan to submit a new drug application to the U.S. Food and Drug Administration for the IV type in 2016 and for the oral tablet version in 2017, and that they would hopefully be on the market soon afterward.

Cara CEO Derek Chalmers acknowledged that other companies also are working toward non-addictive opioids but said his company's drug is less abusable than others. "We're really excited about our data," he said.

Le'Nata Townsend of Louisville, who depends on narcotic medications to control the pain of her sickle cell disease, said while she has never struggled with addiction, she knows that other patients do, and drugs like Cara's "could be helpful for people in pain."

Townsend's mother, Mary Medaries, agreed. She said it can now be difficult for legitimate pain patients to get the medicines they need, especially with a wide-ranging Kentucky law passed in 2012 designed to regulate pain clinics and prevent prescription drug abuse.

"With the new law, it's really gotten tougher on the adult sickle cell patients," Medaries said. "This (medication) would really help because a lot of doctors are getting wary" of prescribing opioids.

Skepticism and caution

But some in the addiction and drug-abuse fields say drugs like these are not the sole answer to the prescription drug-abuse crisis.

"I hope that they continue to work on development of such drugs. But I'm skeptical," said Van Ingram, executive director of the Kentucky Office of Drug Control Policy. "From the Kentucky perspective, we just have not had a good experience with opioid drugs."

Kentucky loses more than 1,000 residents a year to drug overdoses. The problem first emerged in the early 2000s, when growing numbers of residents in the Appalachian region of the state became addicted to Purdue Pharma's OxyContin. The numbers of deaths skyrocketed over the next decade, but in recent years have begun leveling off. Meanwhile, heroin overdose deaths rose from 22 in 2011 to 143 in 2012 in Kentucky.

As part of a settlement in a Virginia criminal case in 2007, Purdue and three of its executives pleaded guilty to intentionally misleading doctors, regulators and patients about OxyContin's addiction risk.

Ingram said it's difficult to blindly trust a drug company's claims, since, "It wasn't that long ago we were told (OxyContin) wasn't that addictive."

Nationally, more than 22,000 Americans died of prescription drug overdoses in 2012, more than 16,000 of which involved opioids, according to the latest research from the U.S. Centers for Disease Control and Prevention.

Dr. James Patrick Murphy, a specialist in pain and addiction medicine with a practice in Southern Indiana, said drugs such as Cara's may help reduce these numbers — but time will tell.

"We're very hopeful for drugs like this," Murphy said. "But until we use it and have some experience with it, it's difficult to get that excited. … There's no silver bullet to treating chronic pain."

Reporter Laura Ungar, who also covers public health for USA Today, can be reached at (502)582-7190 or on Twitter @laura_ungar.