Fentanyl is a synthetic, highly selective opioid with many desirable physicochemical properties, including a high lipophilicity and predictable pharmacokinetics. These properties have an established record in the management of pain in a variety of settings, particularly acute pain and breakthrough cancer pain. Fentanyl was initially developed for parenteral use; however, this is invasive and impractical in the outpatient setting. Unfortunately, the high first-pass metabolism of fentanyl makes oral formulations unfeasible. However, its high lipophilicity allows fentanyl to be absorbed via a number of other routes. Thus new formulations were designed to allow non-invasive methods of administration. Transmucosal and transdermal fentanyl formulations are well established, and have proven useful in the settings of breakthrough cancer pain, emergencies and in the paediatric population. The iontophoretic transdermal system was developed to provide a needle-free system of delivering bolus doses of fentanyl on demand, a novel way of delivering patient-controlled opioid analgesia. Transpulmonary administration of fentanyl remains experimental. The aim of this review is to provide an update on current non-parenteral fentanyl formulations, with attention to their particular pharmacokinetics and features relevant to clinical use in pain management.
Pain is a common symptom that can be complex to treat. Analgesic medications are the mainstay treatment, but there is wide interindividual variability in analgesic response and adverse effects. Pharmacogenomics is the study of inherited genetic traits that result in these individual responses to drugs. This narrative review will attempt to cover the current understanding of the pharmacogenomics of pain, examining common genes affecting metabolism of analgesic medications, their distribution throughout the body, and end organ effects.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.