The opioid crisis in the USA is becoming increasingly worse. In 2016, more than 46 people died every day from opioid related over-dose, and 11.5 million people misuse prescription opioids every year. Opioid use in the UK is not as wide-spread as it is in the USA, but it is rising. Is there possibly a new painkiller from the same drug family that is non-addictive?
Although the crisis is not as bad as in the USA, there has been a rise in opioid prescriptions in the UK. In 2017, GPs prescribed 23.8 million opioid-based painkillers, 10 million more than in 2017, with Northern parts of England four times more likely to be prescribed opioids than the London area. There has also been a steady increase in opioid related deaths in the UK, with more than 2,000 people having died from opioid use in 2016. Obviously, this is nowhere near the 116 deaths per day in the USA but should we be more cautious about the use of opioids?
Opioids are a powerful drug family which originate from poppy seeds. Opioids act on opioid receptors in the brain, usually used therapeutically for pain relief (i.e. analgesia). Opioids work by binding to these receptors, blocking pain signals in the brain, triggering the release of dopamine. The well-known, strong, pain-killers morphine and codeine are naturally occurring opioids found in poppy seeds, and have been used for more than 100 years. However, heroin is a semi-synthetic opioid, meaning it is derived from morphine but slightly changed chemically. You can see from the picture that the structural difference between these three opioids is very small, yet their effects are vastly different. All three have painkilling effects, but heroin is three times more potent than morphine and is an illegal drug. Morphine is (reasonably) controlled and there are laws and regulations in place to ensure a certain purity and potency of the drug. Heroin however does not have these in place, and is much stronger, almost always leading to addiction due to it’s high concentration.
Despite their different therapeutic effects, all can be highly addictive and if a patient has morphine/codeine taken away after having a long-term prescription, it is not uncommon for the patient to eventually turn to heroin in search of some relief. Why are opioids so addictive? Have you ever been told by the pharmacy not to take medicine containing codeine for more than 3 days in a row? This is to limit the chance of addiction. Alongside their ability to inhibit pain, opioids trigger the release of endorphins (i.e hormones associated with a feeling of happiness) in the brain. Once the opioid effects wear off, the patient may want another dose to top-up those feelings again. This is the start of addiction: taking them for the high, not for pain relief. The more you take opioids, the slower your endorphin release becomes and you build up a tolerance. This may not seem like something that could happen to you, but it is far easier to become reliant on opioids than you would assume. We should all be more careful to take medications as directed by medical professionals.
Has new research found a solution, an opioid without the addictive capability? Mei-Chuan Ko and his colleagues from Wake Forest University in the US, have released their research into an opioid which can both block pain and remove the chance for addiction by targeting two different opioid receptors. The first receptor is a pain-relieving one traditionally targeted by opioids, the mu opioid receptor. The second is the nociceptin receptor, and targeting this blocks the brain’s ability to produce an addiction-forming response (i.e. endorphin release) whilst also providing additional pain relief. Pretty impressive. The animal trial results showed the new drug was 100 times better at reducing pain when compared to morphine, and the drug had no apparent addictive properties. When given the option to self-administer either oxycodone (an opioid prescription drug), cocaine, or the new opioid, the monkeys in the trail continually chose either oxycodone or cocaine, not the new opioid. This suggests the addictive brain response was not triggered by the new drug. Even at high doses the new opioid does not cause breathing difficulties, which is a problem with current opioids. The group believes these promising results could see this new opioid available within 6 years if the next clinical trial (in 18 months time) is also successful.
The opioid crisis is a growing issue in developed countries and there doesn’t appear to be a quick fix readily available to those who have abused prescription opioids. The research by Ko et. al. could be an answer to many problems, especially if there really are no addictive properties. That isn’t to say that there may not be other complications/side-effects which they have not yet encountered in trials, but it is a promising discovery. Overall, both health professionals and us, as consumers, should be more cautious about our opioid use whilst they are so readily available.