Kapoor Dovepress 4. Wu WD, WangY, FangYM, Zhou HY. Polymorphism of the micro-opioid 6. Rakvag TT, Ross JR, Sato H, Skorpen F, Kaasa S, Klepstad P. Genetic receptor gene (OPRM1 118 A . G) affects fentanyl-induced analgesia during anesthesia and recovery. Mol Diagn Ther. 2009;13:331–337. 5. Ross JR, Riley J, Taegetmeyer AB, et al. Genetic variation and response to morphine in cancer patients: catechol-O-methyltransferase and multidrug resistance-1 gene polymorphisms are associated with central side effects. Cancer. 2008;112:1390–1403. variation in the catechol-O-methyltransferase (COMT) gene and mor- phine requirements in cancer patients with pain. Mol Pain. 2008;4:64. hTerapeutics and Clinical Risk Management Publish your work in this journal Therapeutics and Clinical Risk Management is an international, peer- reviewed journal of clinical therapeutics and risk management, focusing on concise rapid reporting of clinical studies in all therapeutic areas, outcomes, safety, and programs for the effective, safe, and sustained use of medicines. This journal is indexed on PubMed Central, CAS, Submit your manuscript here: http://www.dovepress.com/therapeutics-and-clinical-risk-management-journal Dovepress EMBase, Scopus and the Elsevier Bibliographic databases. The manuscript management system is completely online and includes a very quick and fair peer-review system, which is all easy to use. Visit http://www.dovepress.com/testimonials.php to read real quotes from published authors. 244 submit your manuscript | www.dovepress.com Dovepress Therapeutics and Clinical Risk Management 2012:8