The Impact of Opioid Analgesics and the Pharmacogenomics of ABCB1 in Opioid Dependence and Pharmacotherapies: A Short Review

Pain is extremely multifaceted in nature, with physical injury being just one of its causes. The most commonly prescribed therapeutic intervention for acute as well as chronic pain (postoperative or otherwise) is Opioids. Opioid analgesics act via the opioid receptors (G protein coupled), that are widely distributed in the central and peripheral nervous system as well as the gastrointestinal tract, producing pain relief. The opioid analgesics are divided into distinct categories depending on the receptor type and their potency. Three major types of receptors mediate analgesic effects, namely, mu (μ), delta (δ) and kappa (κ). These are also further subdivided into different subtypes depending on the duration and onset as rapid-onset, shortacting and long-acting. The neurobiology behind opioid analgesia involves the mesolimbic (midbrain) reward system. There is also increasing scientific evidence that plasma pharmacokinetics, along with the CNS distribution of opioids, is greatly influenced by the P-glycoprotein (P-gp) efflux transporter. The ABCB1 gene is responsible for coding P-gp hence it was postulated that variability in the ABCB1 gene could potentially play an important role in determining why there is interindividual variability towards opioids therapeutic interventions Hence the primary purpose of this review was to compile and understand the research regarding the mechanisms of opioid actions and the effect of genetic variability (ABCB1 gene), on the P-gp transporters regarding their expression/function while also examining the opioid use, abuse and dependence and possibly coming up with some strategies to use pharmacogenomics as a potential tool for solving these issues