Researchers hoping to separate the beneficial, analgesic effects of painkillers from their side effects may have finally developed a drug that offers pain relief with less risk of addiction. Technology Review reports.
Opioids like morphine remain the top choice for relieving the severe pain that can result from cancer and surgery. But they also boost dopamine pathways in the brain, causing a rewarding high that could trigger repeated, chronic use and eventually addiction.
Now, Nektar Therapeutics is developing a new kind of opioid that enters the brain too slowly to be abused.
In fact, painkiller abusers found this investigational opioid "boring," said chief medical officer, Rob Medve: "There is no joy or euphoria associated with the drug." And still, human trials show that the compound increases pain tolerance.
Nearly two million Americans abuse or are addicted to opioids, and nearly 14,000 overdose on these drugs in a year, according to the U.S. Department of Health and Human Services. Researchers have been trying to develop more benign versions for decades.
Opioid drugs have a “higher abuse liability” the faster they get into the brain. For example, the rush of heroin into the nervous system is associated with euphoria. “We know you can get very good analgesia by having an opioid go in slowly to the brain and not produce the dopamine spike,” Medve said. “They are separable.”
This is how the new drug hopes to reduce the risk of abuse:
Nektar’s approach is to add a side chain to a derivative of morphine, which changes the way the molecule behaves in the body. The addition slows the rate at which the compound enters the brain, in part by making it more difficult for it to cross the blood-brain barrier, the protective layers that surrounds blood vessels in the brain and regulates what can enter.
Human safety trails have been completed, and the company expects to have early efficacy results this month.
Image: morphine addiction cure ca. 1900 / Wikimedia