Opioid addiction has remained a hot topic of discussion so far this year. Opioid is an addictive substance taken to relive pain. But those who take it gradually become addicted to the drug,whose intake beyond limit could be fatal. For decades, scientists have been trying to develop an opioid drug, whichnot just helps relieve pain, but alsoposes no side effect.Now, a scientist has developed one such drug.

In early 19th century, Morphine was introduced to control addiction to opium. That time, Codeine was considered as a non-addictive painkiller. There still are cases of addiction as all opioid drugs act similarly in the brain. They influence mu-opioid receptor, a neural receptor that manages pleasure, pain, relief and need.

However, there came hope with a discovery by Laura Bohn, a scientist who in 2000 found out something about a protein called beta-arrestin. This protein attaches with the opioid receptor when activated by an opioid drug such as morphine.

She realized while experimenting on mice that when morphine was given to mice that do not have beta-arrestin, the drug did relive pain, but without posing anyside effect. The mice experienced regular breathing, tolerance to the drug and had less withdrawal effects with certain doses.

"The hope is you'd have another molecule that looks like morphine and binds to the same receptor, but the way it turns the receptor on is slightly different", said Dr. AashishManglik, a researcher at Stanford University School of Medicine who studies opioid receptors.

A team of researchers, including Manglik, inspired by Bohn's discovery created a drug that could reduce side effects of beta-arrestin. The team ran 3 million possibilities through the computer and chose 23 best candidates to test in a lab. One chemical, PZM21, turned their imaginations into reality. It activated opioid receptor without influencing beta-arrestin. The finding is reported in Nature on Wednesday.

According to a report in Business Insider by Lisa Rapaport, "Scientists are testing an experimental medicine that’s designed to have the painkilling power of morphine without some of the dangerous side effects that can lead to overdose deaths. The compound is so new it doesn’t have a name, just a number. It’s only been tested in mice, and it needs years of additional animal studies before researchers can even start trials to see if it works safely in humans."

“The dopamine circuit is one of the primary reward circuits in the brain, and its over-activation leads to repeated seeking of the reward stimulus – in this case, morphine (or related opioids),” said Shoichet, a researcher in pharmaceutical chemistry at the University of California, San Francisco.

A report published in LA Times informed, "What if you could design a drug that has all the pain-relieving power of morphine but none of its dangerous or addictive side effects? Scientists have spent years trying to do just that, and on Wednesday, they unveiled one of their most promising compounds yet — a chemical concoction they dubbed “PZM21.”"

Mice treated with PZM21 did not find it addictive, as evidenced by the fact that they were no more likely to return to a place where they got the drug than to visit a similar chamber where they could get a saline solution. Plus, while the animals became hyperactive after a dose of morphine — considered a sign of the drug’s addictive power — they remained perfectly calm after getting a comparable dose of PZM21.