Individual variability in clinical effect and tolerability of opioid analgesics - Importance of drug interactions and pharmacogenetics

Drug interactions and pharmacogenetic differences may lead to therapeutic failure or serious side effects of opioid analgesics. Many interactions involve combinations with antidepressants and antiepileptics, which are highly relevant drugs in patients suffering from pain. To prevent unfavourable drug interactions it is important that clinicians pay close attention and use electronic drug interaction checkers when treatments are initiated or discontinued. For the management of issues related to pharmacogenetic differences, blood-based CYP genotyping is available as routine test at many laboratories, and provide a valuable tool for proper choice of drugs and doses for treatment of pain and other diseases.