Milnacipran is a serotonin and norepinephrine reuptake inhibitor (SNRI). It is used in the management of fibromyalgia, major depressive disorder, generalized anxiety disorder, chronic musculoskeletal pain and diabetic peripheral neuropathy. It is generally believed that 5HT and NE participate in the modulation of endogenous analgesic mechanisms by way of the descending inhibitory pain pathways in the brain and spinal cord. Although the specific mechanism of action remains unclear, some studies have proposed that low levels of 5HT may be associated with increased sensitivity to pain - a condition that could subsequently be improved by milnacipran's capacity to enhance the presence of 5HT by inhibiting its reuptake via serotonin transporters at synaptic clefts. Furthermore, in the CNS it is also generally believed that NE released from descending pathways can mitigate pain sensations via eliciting inhibitory effects on alpha-2A-adrenoceptors on central terminals of primary afferent nociceptors, by direct alpha-2-adrenergic action on pain-relay neurons, and by alpha-1-adrenoceptor-mediated activation of inhibitory interneurons. Such NE pain mitigation is consequently also enhanced by milnacipran's ability to enhance the presence of NE by inhibiting its reuptake via norepinephrine transporters at synaptic clefts

Milnacipran SNRI - Norepinephrine reuptake Inhibition pathway References