2017/06/06
The common medicines for pain are over-the-counter analgesics like Ibuprofen, paracetamol, aspirin or anti-inflammatory agents. For severe pain, doctors often prescribe more powerful painkillers. One set of painkillers that were widely prescribed in the late 1990s and early 2000s belonged to the opioids family, which are very effective but are known to have side effects. Derived from opium, opioids block the transmission of pain messages in the nervous system to the brain. But they also tend to stimulate the brain and produce feelings of pleasure or a “high” among patients. This side effect made them highly habit forming and addictive. Patients liked to continue taking these medicines even when they were not required for pain relief, using them as stimulants.
Many people in the US have fallen victim to opioid addiction. Over 15,000 opioid overdose deaths were reported in 2008, which was more than motor vehicle deaths in that year [1], rising to 33,000 such deaths in 2015. The Centre for Disease Control (CDC) reports that in 2017, more than 115 people in the US died every day because of opioids overdose [2], which may result from misuse of prescription pain relievers as well as street drugs. It has become a serious public health crisis.
The use of opioids for pain relief became popular as they were hailed as safe drugs. They were promoted through marketing campaigns and doctors began prescribing them. As they were addictive, overdoses became common from 2000 onwards. The dramatic increase in morbidity due to opioid pain relievers (OPRs) has caused a crisis [3]. Restricting access does not help, because patients turn to unsafe street alternatives if they cannot buy the prescribed versions. As a result, doctors are now becoming wary of prescribing the opioid drugs. Drug companies are also under investigation in the way they marketed their painkillers leading to the opioid epidemic: Purdue Pharma faces lawsuits in the US for using deception to market its drug, OxyContin [4].
There is therefore an urgent need to develop new and safer painkillers. Research is being conducted to develop painkillers that have fewer side effects and can control pain without becoming an addiction. Scientists are trying to modify opioid molecules to get rid of their harmful effects while others are testing marijuana molecules [5].
Attempts to isolate the harmful molecules in opioids have found that a protein, beta-arrestin 2 is the culprit, causing the negative effects. While pain is controlled when opioids connect with receptors on nerve cells, they also attach themselves to other receptors in all parts of the body. This causes the addiction.
A new drug, PZM21 has been developed, which is a breakthrough as it does not have beta-arrestin 2 and has been found to be very effective in pain relief without side effects [6,7]. Oliceridine is another effective painkiller with fewer side effects. Another drug that is being experimented is kratom [8]. Cannabinoids, which are derived from marijuana or the hemp plant, are also being tested. Though they are not strong painkillers, they can be combined with opioids for better pain relief. Drugs that can use the body’s natural cannabinoids are also being tested [4]. An innovative line of research is to direct pain-killing drugs specifically to the parts of a person’s body that are feeling pain. Such areas are acidic, so drugs could be targeted to those particular areas. It will, however, take some time for these drugs to be commercially available.
The opioid crisis shows how health of populations is jeopardized when the side effects of drugs are not evaluated properly. It should serve as a lesson for companies and doctors alike to market and prescribe drugs carefully [10].
