Single nucleotide polymorphisms as predictors of treatment efficacy and adverse effects of morphine in palliative medicine: a literature review.

Introduction: Pain has a significant negative impact on the quality of life of cancer patients and implies numerous clinical consequences. Moderate to severe pain is common in patients receiving palliative care. A major issue is the individual variability resulting in different degrees of response to the analgesic effects of opioids, including morphine, and to the occurrence of their adverse effects. According to one of the theories of pharmacogenomics, single nucleotide polymorphisms (SNPs) are associated with opioid metabolism. Material and methods: A literature review of the PubMed database identified 18 scientific articles concerning SNPs that affect the analgesic effects and adverse effects of morphine or other opioids, per morphine equivalent, from which additional 22 scientific articles were retrieved. Results: The review identified SNPs in the genes OPRM1 A118G, COMT rs4680, ABCB1 C3435T, IL-6, IL-8, TNF-a, TAOK3, HTR3B, UGT1A1/UGT1A8 and OPRM1 Arg181Cys, which were found to affect both the occurrence of potential adverse effects and the different demand in palliative care patients for a dose of morphine that will effectively relieve pain. SNPs were found to significantly affect morphine metabolism; the determination of this effect is individual-based. Most studies were conducted in small groups of individuals from ethnically diverse populations, which, if mutations are present, may significantly affect the efficacy of opioid-related SNP assays and the response of patients to the analgesic treatment administered. Conclusions: Findings raise the prospect of the use of SNPs in clinical practice as part of personalised medicine in the future. [ABSTRACT FROM AUTHOR]