Differential indications of opioids in pain therapy

Due to their strong analgesic potency opioids are highly effective in the therapy of acute and particularly cancer-induced chronic pain; however, the individual opioids differ considerably with respect to their pharmacokinetic and physicochemical properties and may therefore not be equally applicable for every patient. Caution should be taken especially in patients with impaired organ function. Furthermore, the metabolism of opioids leads to active or inactive metabolites. This process can be substantially influenced by genetic polymorphisms or drug interactions. Knowledge of all these factors for individual opioids, which influence the efficacy and side effects, is therefore crucial. In this review the pharmacology, clinical applications, metabolism and genetic factors of the most important opioids used for pain management are discussed.