Genetic polymorphisms and human sensitivity to pain and opioids

: It has been known widely that sensitivity to pain and opioid analgesics varies widely among individual subjects. Because of this variability, a dose of an opioid analgesic that can produce satisfactory pain relief without adverse effects in some patients might cause underdosing or overdosing in other patients, which is often problematic in the clinic. Individual differences can be attributed to both genetic and environmental factors, although the relative influence of each of these factors can be diverse. Numerous molecules have been identifled to be involved in the transduction, conduction, transmission and modulation of pain, as well as pharmacological effects of opioids. Further, many technologies of genotyping polymorphisms, most often single nucleotide polymorphisms (SNPs), have been developed and advanced, leading to accelerated understanding of many associations between various genetic polymorphisms and sensitivity to pain and opioids. In this article, we review the evidence of these associations accumulated thus far.