Opioids for chronic pain: molecular and genomic basis of actions and adverse effects.

Purpose of Review: Opioid analgesics are being increasingly used for pain control in both cancer and noncancer patients. Despite thousands of years of their use, the biological basis of their action and adverse effects are only now being understood. It is important to understand these agents better so that the potentially large sections of the population who may eventually be eligible to receive therapeutic opioids are treated rationally and safely.
Recent Findings: Recent advances in pain physiology, molecular biology of neurotransmission, in-vivo neuroimaging and the study of genomic influences on drug receptors and metabolism are beginning to clarify how opioids work, how they differ from each other and how they may cause harm.
Summary: Understanding the biological basis of how opioids work and produce adverse effects should help us to make better choices of which drugs to use for specific populations. Identifying individual genetic differences in opioid receptors and drug metabolism pathways may also pave the way to more targeted and safer medication in the future.