Browsing by Author "Lundén, Anniina"

Circadian clocks govern our bodily rhythms both in health and disease. A diurnal pattern in neuropathic pain has been demonstrated in humans, but whether analgesics used to treat it have clinically relevant circadian effects is still largely unknown. This systematic literature review aims to describe the relationship between circadian rhythms and the specific analgesics used in the treatment of neuropathic pain. Based on current neuropathic pain drug treatment recommendations, analgesics of interest were chosen as gabapentin, pregabalin, carbamazepine, oxcarbazepine, serotonin-noradrenaline reuptake inhibitors, tricyclic antidepressants, opioids, capsaicin, and lidocaine. A literature search was conducted on PubMed, Web of Science, Cinahl, and Medic electronic databases, through August 2023. Publications were screened for human clinical studies and full-text availability. Data were collected from studies conducted on chronic pain patients or healthy volunteers, that describe the use of analgesics of interest and provide data on any measurable circadian-related marker or diurnal variation in drug effects. A total of 32 studies were included. Evidence of diurnal variations were found in the pharmacokinetics of morphine and tricyclic antidepressants as well as in the analgesic effects of dihydrocodeine and tramadol. Serotonin-noradrenaline reuptake inhibitors do not seem to disturb the normal circadian patterns seen in melatonin, cortisol, or body temperature levels. In contrast, tricyclic antidepressants may affect melatonin and cortisol profiles. The diurnal pattern of neuropathic pain is preserved during gabapentin, morphine, and nortriptyline treatment. Drug-induced changes in different sleep parameters were seen in several of the analgesic groups, but the possible circadian dependence of these effects is unclear. The results of this review suggest that circadian rhythms may influence the pharmacokinetics and pharmacodynamics of analgesics. The clinical significance of these circadian effects in humans needs further investigation. A better understanding of the relationships between circadian rhythms and non-opioid analgesics can eventually lead to improved and personalized treatment strategies for neuropathic pain.