Opioids and opioid receptors; understanding pharmacological mechanisms as a key to therapeutic advances and mitigation of the misuse crisis

Adverse Events of the Long-Term Use of Opioids for Chronic Non-cancer Pain: A Narrative Review

“…Opioids play a significant role in modulating pain, mood, stress response, and digestion [ 18 , 19 ]. They can control CNCP when alternative therapeutic approaches have proven inadequate in pain management [ 18 ].…”

“…Opioids play a significant role in modulating pain, mood, stress response, and digestion [ 18 , 19 ]. They can control CNCP when alternative therapeutic approaches have proven inadequate in pain management [ 18 ]. This class of drugs is not typically the first line of intervention, due to their potential risks; they are often prescribed when other treatments such as nonsteroidal anti-inflammatory drugs (NSAIDs) or physical therapy have failed to provide sufficient relief [ 2 ].…”

“…With a history spanning over 5,000 years, opioids have been employed as analgesics [ 20 ]. Substances like morphine, oxycodone, and hydrocodone bind with the opioid receptors within the central and peripheral nervous system, inducing changes in pain perception and facilitating analgesic effects [ 18 , 19 ].…”

“…The mu, kappa, and delta opioid receptors each have unique roles within the modulation of pain and the pharmacological effects of opioids. Mu receptors are primarily responsible for the analgesic and sedative effects of opioids and are known to mediate several adverse effects, including constipation and the risk of respiratory depression [ 18 , 19 ]. In contrast, kappa receptors, while also contributing to analgesia and sedation, are distinguished by their role in inducing aversive affective states and psychotomimetic effects, which encompass altered sensory perceptions and cognitive processes [ 18 , 19 ].…”

“…Mu receptors are primarily responsible for the analgesic and sedative effects of opioids and are known to mediate several adverse effects, including constipation and the risk of respiratory depression [ 18 , 19 ]. In contrast, kappa receptors, while also contributing to analgesia and sedation, are distinguished by their role in inducing aversive affective states and psychotomimetic effects, which encompass altered sensory perceptions and cognitive processes [ 18 , 19 ]. The functions of delta receptors, although not as extensively characterized, appear to contribute to pain modulation and may influence emotional regulation, offering a distinct profile of effects from mu and kappa receptors [ 18 , 19 ].…”