Papaver libanoticumis an endemic plant to Lebanese region (family Papaveraceae) that has not been investigated before.The present\nstudy aimed to explore the analgesic activity of dried ethanolic extract of Papaver libanoticum (PLE) using tail flick, hot plate, and\nacetic acid induced writhingmodels in mice.The involvement of opioid receptors in the analgesic mechanism was investigated using\nnaloxone antagonism. Results demonstrated that PLE exhibited a potent dose dependent analgesic activity in all tested models\nfor analgesia. The analgesic effect involved activation of opioid receptors in the central nervous system, where both spinal and\nsupraspinal components might be involved.The time course for analgesia revealed maximum activity after three hours in both tail\nflick and hot plate methods, which was prolonged to 24 hours. Metabolites of PLE could be responsible for activation of opioid\nreceptors. The EC50 of PLE was 79 and 50 mg/kg in tail flick and hot plate tests, respectively.The total coverage of analgesia by PLE\nwas double that of morphine in both tests. In conclusion, PLE proved to have opioid agonistic activity with a novel feature of slow\nand prolonged effect.The present study could add a potential tool in the armaments of opioid drugs as a natural potent analgesic\nand for treatment of opioid withdrawal syndrome.
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