Prospective Study About Clinical and Pharmacogenetic Safety of Opioid Use for Chronic Pain

Aim of this project is to customize the choice of the strong opioid in the treatment of cancer chronic pain through the identification of patient clinical history and pain characteristics, moreover in the analysis the investigators will also correlate the clinical efficacy and safety of opioid treatment with pharmacokinetic and pharmacogenetic patterns in order to identify variables able to predict the efficacy of the treatment or the patient susceptibility towards a specific treatment. Furthermore with this study the investigators want to identify the pharmacogenomic characterization responsible for pharmacokinetic variability in the conversion between morphine and other opioids, in order to validate the currently available conversion tables from a pharmacokinetic viewpoint, estimating the influence of the most common genetic polymorphisms, and if this characterization could be useful and cost-effective. This study will also focus on the specific clinical-pharmacological response in the elderly and between male and female and on the interactions between opioids and those anticonvulsant and antidepressant drugs routinely used in the pain therapy (study of pharmacovigilance).