Association of UGT2B7 and ABCB1 genotypes with morphine-induced adverse drug reactions in Japanese patients with cancer

To investigate the effects of genetic polymorphisms on morphine-induced adverse events in cancer patients. We examined the relation of morphine-related adverse events to polymorphisms in UDP-glucuronosyltransferase (UGT) 2B7, ATP-binding cassette, sub-family B, number 1 (ABCB1), and μ-opioid receptor 1 genes in 32 Japanese cancer patients receiving oral controlled-release morphine sulfate tablets. The T/T genotype at 1236 or TT/TT diplotype at 2677 and 3435 in ABCB1 was associated with significantly lower frequency of fatigue (grades 1–3) (P = 0.012 or 0.011, Fisher’s exact test). The UGT2B7*2 genotype was associated with the frequency of nausea (grades 1–3) (P = 0.023). The frequency of nausea was higher in patients without UGT2B7*2 allele than others. The diplotype at 2677 and 3435 in ABCB1 was associated with the frequency of vomiting (grades 1–3) (P = 0.011). No patient whose diplotype was consisted of no GC allele at 2677 and 3435 suffered from vomiting. Our findings suggest that pharmacogenetics can be used to predict the risk of morphine-induced adverse events.