By Andrea Flores Esparza
The urgency to combat the Opioid Addiction Crisis surges from the fact that the misuse of prescribed and illicit opioids is the main cause of drug-related deaths across the world (Alho et al., 2019). Statistical analysis portrays that 21-29% of patients who were prescribed opioids misuse them, and around 8-12% develop opioid-use disorder (National Institute of Health, 2020). Opioid-use disorder refers to the “chronic and relapsing problematic” misuse of opioids that leads to suffering (Alho et al., 2019). Although regulations with regards to the prescription of opioids have been established, the number of cases of opioid overdose and addiction has continued to increase, especially amongst the younger population. At the beginning of the epidemic in the 1990s, the population who suffered from opioid addiction were mainly middle-aged people who had fallen into the cycle due to unregulated pharmacological prescriptions. However, nowadays the younger generations have been exposed to the illegal opioid compounds such as heroin (Davis, M). In order to get a full grasp of this public health problem it is important to underline the physiological impacts of opioids as well as the history of these chemical compounds.
The use of these pain killers can be traced back 3,000 years ago in the ancient Mesopotamian, Egyptian and Minoan civilisations. These civilisations discovered the opium poppy (i.e. Hul Gil). It is colloquially known as the “the joy plant” because the opium in this flower was used to treat chronic pain and stimulate feelings of pleasure (DEA Museum).
During the 19th century, chemical compounds known as opiates were identified from opium, including codeine and morphine. In the following century the pharmaceutical companies were able to synthetically produce substances that were chemically similar to opiates (Davis, M). Hence opioids refer to the class of drugs, synthetic or naturally synthesised, chemical compounds found in the opium poppy that induce pain relief (Butanis, B). Throughout the 80s and the 90s, pharmaceutical companies guaranteed the public that the use of opioids did not lead to addiction, and thus the healthcare providers began to prescribe these medicaments due to their effective pain relief (National Institute of Health, 2020). However, their additive characteristics caused their use to increase exponentially, consequently leading to an opioid addiction crisis that is still present today (Davis, M). This encouraged scientists to research the physiological and psychological effects of opioids in the human body to better understand the foundation of opioid addiction.
The causes of opioid addiction may be difficult to identify as it is influenced by a combination of social, genetic and environmental factors. However, it has been discovered that opioids act on the endogenous opioid system (U.S. National Library of Medicine, 2020). This system has been found to have a major role in the regulation of mood, including feelings of pleasure, as well as the regulation of pain and addictive behaviours (U.S. National Library of Medicine, 2020; Peciña, M. et al, 2018). The endogenous opioid system is comprised of a number of endogenous opioids (i.e. produced naturally by the body) which bind to their respective receptors to induce changes in mood and pain. For instance, endorphins bind to opioid receptors to inhibit pain signals and stimulate pleasure whilst suppressing the release of noradrenaline, a hormone and neurotransmitter involved in the sympathetic nervous system response (Healthline Editors, 2017).
When exogenous opioids (i.e. substances not produced within the body) are introduced, they can induce strong changes in mood and feelings of both pain and pleasure (Davis, M). This is because their chemical structure enables them to bind to opioid receptors and thus elicit feelings of pleasure whilst inhibiting signalling of pain. Hence, they have been medically prescribed to treat chronic pain.
In fact, opioid drugs have been found to have a stronger affinity to opioid receptors than endorphins. Their binding signals the release of dopamine, a neurotransmitter associated with the feelings of pleasure and euphoria (Davis, M.; Psychology Today). The body gains tolerance to these substances by either decreasing the number of opioid receptors or making them less responsive to the same dose (Davis, M). Therefore, he states that patients find themselves forced to take higher dosages to stimulate the same feelings. Higher dosages can be dangerous for the body as it would decrease norepinephrine levels drastically, potentially leading to loss of consciousness or death. In order to counteract the decrease in norepinephrine, the body increases the number of norepinephrine receptors to detect smaller concentrations. Since opioid drugs stimulate the release of dopamine whilst suppressing the release of norepinephrine, the individuals are in a happy and relaxed state where they do not experience any pain during the treatment. However, by reducing the levels of norepinephrine, other bodily functions can be dysregulated, including breathing, blood pressure and digestion.
Research has suggested that at this point, the body becomes dependent on opioid drugs to maintain the physiological levels of norepinephrine (Davis, M). Nonetheless, when this new cycle is disrupted and the individual drastically decreases their use of opioid drugs, the levels of norepinephrine gets disrupted once again. Hence, during the withdrawal period, individuals would experience temporary muscle and stomach aches, fever and nausea due to the increased levels of norepinephrine. These symptoms can be unbearable for high dosage users causing disengagement to be very difficult to obtain (Davis, M). Hence, leading to an addiction cycle in which users find themselves taking opioids to prevent them from feeling these symptoms instead of taking them to reduce pain and/or feel pleasure.
The most effective way to tackle this issue is to offer a combination of both medical and psychological treatments to patients suffering from opioid-use disorder as this has been linked to other mental health issues. These patients require long-term treatment as opioid addiction is characterised by “episodes of relapse and remission”, making it challenging to achieve successful results in a short period of time (Alho, H et al., 2019). Methadone and buprenorphine are medicaments that are commonly use during the medical treatment as they prevent the patient from experiencing withdrawal symptoms without stimulating the psychoactive effects of opioids (Davis, M). Moreover, it also is important to address the rate of deaths caused by opioid overdose. Numerous interventions have been made to implement regulations for the prescriptions of opioids as well as social programmes to address the misuse of illicit opioids. However, on medical terms, naloxone has been found be very useful whilst treating patients with overdose as it has a higher affinity to the opioid receptors, blocking them as well as replacing the opioids that were already bound to these (Davis, M). Although numerous actions have been taken, it is important to continue monitoring the use of opioids as well as providing treatment to patients suffering from opioid-use disorder as their livelihoods and the livelihoods from the people that surround them can be heavily affected by the misuse of these compounds.
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Imperial Bioscience Review 