NIDA Session Discusses Scientific Solutions to Address Opioid Crisis


Opioid misuse is at epidemic proportions in the United States, with deaths due to opioid overdose quadrupling since 1999. Shedding some light on ways to address this problem through science, the National Institute on Drug Abuse (NIDA) sponsored an Annual Meeting session on therapeutic developments that may one day potentially be used to help reverse this public health crisis.

According to Thomas Jenkins, Ph.D. (pictured above), executive vice president and chief scientific officer at Elysium Pharmaceuticals, up to 71 percent of people who are prescribed opioids fail to properly discard the drugs after discontinuing use, increasing the risk that they will be used by other household members. “There are current options for curbing diversion of opioids such as ‘take-back programs’ and widespread changes in prescription practices of health professionals, but more needs to be done.”

To provide more options for reducing diversion, Elysium has developed the XpiRx (pronounced expire) investigational program. XpiRx is a pill that consists of the opioid receptor agonist hydrocodone and the opioid antagonist naltrexone. According to Jenkins, human studies have found that combined opioid agonist and opioid antagonist therapies are less likely to be abused than opioid agonists alone. However, this particular investigational therapy goes a step further in deterring abuse, said Jenkins.

“Opioids medications have a half-life of 70 years,” said Jenkins. According to results of studies with opioid-dependent animals presented by Jenkins, XpiRx loses its effectiveness at a faster rate than currently available opioid painkillers, with reduced “liking” for the drug starting at six months and full blockade of hydrocodone effects occurring from eight months to a year.

Another abuse-deterrent program by Elysium involves a version of an opioid agonist that has been shown in preliminary animal trials to be activated when it interacts with a specific protein in the intestines, reducing the potential for the drug to be misused by snorting or injection. The drug is in a phase 1 clinical trial in which it is being compared with non-abuse-deterrent opioids.

The session also highlighted monoclonal antibodies as a potential deterrent to initiating or continuing use of heroin. “Antibodies usually do not cross the blood-brain barrier,” said Kim Janda, Ph.D., an immunologist and director of the Worm Institute for Research and Medicine at the Scripps Research Institute. “Antibodies function to bind to the drug and prevent the drug from crossing the blood-brain barrier.”

Janda presented data from two animal studies—one in primates and another in rodents—with the technology coined the “heroin vaccine.” Results from the primate study showed that the antibody was effective in preventing heroin from crossing the blood-brain barrier, while results from the rodent trials showed that rats with heroin dependence were less likely to seek out the drug and experience compulsive heroin self-administration following abstinence.

“Vaccines are important and would be a great therapy [to thwart opioid abuse],” said Janda. “They require no continued daily compliance, have no significant chance of being used illicitly, and [have a potential] to reduce risk of overdose.”

In an interview, Ivan Montaya, M.D., the deputy director of the Division of Therapeutics and Medical Consequences at NIDA and chair of the session, said that the session was very informative and much needed, especially for addiction psychiatrists. “The rate of drug overdose is greater than that of deaths by automobiles. … The current opioid drug epidemic greatly impacts addiction psychiatry.”

(Image: David Hathcox)