A Study Investigating the Synergistic Analgesic Effects of Nefopam and Medetomidine in a Multimodal Pain Management Approach in Mice

This study explored the type of analgesic interaction between nefopam and medetomidine and evaluated their safety profiles in a mouse model as no previous studies had examined their pharmacological interaction at the antinociceptive level. Adult male and female mice (n=6-7 per group) were administer...

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Bibliographic Details
Main Authors: Hazem Khalil, Gada Faris
Format: Article
Language:English
Published: Egyptian Society for Animal Management 2025-07-01
Series:Journal of Applied Veterinary Sciences
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Online Access:https://javs.journals.ekb.eg/article_435540_1d05c40f7834e25c2e8624581b024360.pdf
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Summary:This study explored the type of analgesic interaction between nefopam and medetomidine and evaluated their safety profiles in a mouse model as no previous studies had examined their pharmacological interaction at the antinociceptive level. Adult male and female mice (n=6-7 per group) were administered ascending/descending doses of nefopam or medetomidine alone or in a combination via intraperitoneal injection. Analgesic efficacy was determined using the hot plate test (55°°C) and writhing reflex technique. The ED50 values were calculated via the up-and-down method, isobolographic analysis assessed drug interaction types and LD50 values were derived to assess acute toxicity. Nefopam alone exhibited an ED50 of 5.66 mg/kg intraperitoneal (I.P.), while medetomidine showed an ED50 of 93.05 mg/kg I.P. Combined administration of nefopam with a fixed medetomidine dose (0.65 mg/kg) reduced the ED50 of nefopam by 44%. At the double ED50 dosage for each drug, concurrent intraperitoneal injection of the two drugs completely inhibits the writhing reflex (100%) elicited by acetic acid compared with each drug alone and with the control group. Isobolographic analysis confirmed synergetic interaction between two drugs at 1:1 and 0.5:0.5 of ED50 ratios, with interaction indices (y) of 0.92 and 0.58, respectively. The LD50 values were 78.46 mg/kg (nefopam) and 1230.75 µg/kg (medetomidine), yielding therapeutic indices (LD50/ED50) of 14 and 13, indicative of wide safety margins. These findings demonstrate a potent synergistic analgesic effect between nefopam and medetomidine, allowing for significant dose reductions without losing efficacy. This combination’s favorable safety profile supports its clinical potential as a non-opioid alternative for acute pain management.
ISSN:1687-4072
2090-3308