loperamide brands

Molecular formula: C29H33ClN2O2

Enteric neurons synthesize and release endogenous opioid peptides and other neurotransmitters, such as acetylcholine and substance P. Endogenous opioids bind to opioid receptors expressed on these neurons to regulate gastrointestinal signalling, motility, and balance of fluids and electrolytes. Loperamide acts on the mu (μ)-opioid receptor expressed on the circular and longitudinal intestinal muscle. Receptor binding leads to the recruitment of G-protein receptor kinases and the activation of downstream molecular cascades that inhibit enteric nerve activity. By inhibiting the excitability of enteric neurons, loperamide suppresses neurotransmitter release, pre-synaptic and post-synaptic inhibition of transmission of excitatory and inhibitory motor pathways, and secretomotor pathways. Loperamide inhibits the release of acetylcholine and prostaglandins, thereby reducing propulsive peristalsis and increasing intestinal transit time. Loperamide stimulates the intestinal absorption of water and electrolytes by inhibiting calmodulin. Loperamide can bind to and hyperpolarize submucosal secretomotor neurons, promoting dry, hard stools. ... The present study investigates the mechanism of the central analgesic effect of loperamide. Adult male Sprague-Dawley rats were subjected to surgery for catheter placement. Following baseline testing, different groups of rats were administered fixed intrathecal doses (1 ug, 3 ug, 10 ug and 30 ug) of loperamide and morphine. Analgesia was compared employing Hargreaves paw withdrawal apparatus at 15 min, 30 min, 60 min, 90 min and 120 min. Additionally, CTOP, a specific mu-opioid receptor antagonist was co-administered with loperamide to examine the mu-opioid receptor mediated loperamide analgesia. Furthermore, nefiracetam, a calcium channel opener, was co-administered with loperamide or morphine to evaluate the involvement of Ca(2+) channels in loperamide showed an analgesic effect which was comparable to morphine. However, loperamide produced longer analgesia and the analgesic effect was significantly better at 42 hr and 49 hr compared to morphine. CTOP completely reversed loperamide analgesia. Though nefiracetam significantly reversed loperamide analgesia, it did not have any effect on morphine induced analgesia. Our findings suggest that loperamide administered intrathecally produces analgesia which is mediated through mu-opioid receptor and subsequent blockade of downstream calcium channels. The effects of the antidiarrheal agent loperamide on high-voltage-activated (HVA) calcium channel activity and excitatory amino acid-evoked responses in two preparations of cultured hippocampal pyramidal neurons were examined. In rat hippocampal neurons loaded with the calcium-sensitive dye fura-2, rises in intracellular free calcium concentration ([Ca2+]i) evoked by transient exposure to 50 mM K(+)-containing medium [high extracellular potassium concentration ([K+]o)] were mediated by Ca2+ flux largely through nifedipine-sensitive Ca2+ channels, with smaller contributions from omega-conotoxin GVIA (omega-CgTx)-sensitive Ca2+ channels and channels insensitive to both nifedipine and omega-CgTx. Loperamide reversibly blocked rises in [Ca2+]i evoked by high [K+]o in a concentration-dependent manner, with an IC50 of 0.9 +/- 0.2 microM. At the highest concentration tested (50 microM), loperamide eliminated rises in [Ca2+]i evoked by high [K+]o, a result otherwise achieved only in Ca(2+)-free medium or by the combined application of nifedipine, omega-CgTx, and funnel web spider venom to Ca(2+)-containing medium. The action of loperamide was neither naloxone sensitive nor mimicked by morphine and was seen at concentrations substantially less than those required to block influx of Ca2+ through the N-methyl-D-aspartate (NMDA) receptor-operated ionophore. Similar results were obtained in cultured mouse hippocampal pyramidal neurons under whole-cell voltage clamp. Voltage-activated Ca2+ channel currents carried by bariu

Source: PubChem (NCBI) · compound 3955