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

Document Type : Original Article

Authors

Department of Physiology, Biochemistry and Pharmacology, College of Veterinary Medicine, University of Mosul, Mosul, Iraq

Abstract

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.

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Main Subjects

References

ABDUL HAMEED, Y., and NASER, A., 2025. Exploring the anxiolytic and neurobehavioral benefits of serratiopeptidase in mice. Journal of Applied Veterinary Sciences, 10(1), pp. 57–63. https://dx.doi.org/10.21608/javs.2024.330246.1455
AL-JADER, G.H., and TAQA, G.A., 2014. Isobolographic analysis of the antinociceptive interaction between tramadol and diphenhydramine in mice. International Journal of Enhanced Research in Science, Technology & Engineering, 3(2), pp. 45–53. 
AL-AWWADY, A. N., HASAN, A. N., and ABDUL-MAHDI KADHIM, W., 2020. Comparison of paracetamol vs. paracetamol nefopam combination vs. paracetamol tramadol combination intravenous infusion for intraoperative and immediate postoperative analgesia for laparoscopic cholecystectomy. La Prensa Medica Argentina, 106, S1.
AREMU, A., ORIDUPA, O.A., and BASHAR, N.B., 2024. Effect of different fractions of Lawsonia inermis Linn on haematobiochemical changes, osmotic fragility, and lipid profile in streptozotocin-induced diabetic Wistar rats. Journal of Applied Veterinary Sciences, 9(3), pp. 19–30. https://dx.doi.org/10.21608/javs.2024.276758.1328
ALQAYSI, M. G. I., and ALABBAS, N. N. A., 2024. The properties of nefopam as analgesic co-administration with caffeine as adjuvant in induced pain in mice. Journal of Research in Pharmacy, 28(5). http://dx.doi.org/10.29228/jrp.836
ANTAL, M. 2025. Molecular Anatomy of Synaptic and Extrasynaptic Neurotransmission Between Nociceptive Primary Afferents and Spinal Dorsal Horn Neurons. International Journal of Molecular Sciences, 26(5), 2356. https://doi.org/10.3390/ijms26052356
BARRETT, J. E. 2015. The pain of pain: challenges of animal behavior models. European Journal of Pharmacology, 753, 183–190. https://doi.org/10.1016/j.ejphar.2014.11.046
BAKER, S.A., AL-MODARESS, S.S. and AL-MALLAH, K.H., 2025. Histopathological study of the acute and chronic toxic effects of dimethyl mercury on liver and kidney of male albino rats. Journal of Applied Veterinary Sciences, 10(2), pp. 137-143. https://doi.org/10.21608/javs.2025.364375.1544
CHAE, J. W., KANG, D. H., LI, Y., KIM, S. H., LEE, H. G., CHOI, J. I., YOON, M. H., and KIM, W. M., 2020. Antinociceptive effects of nefopam modulating serotonergic, adrenergic, and glutamatergic neurotransmission in the spinal cord. Neuroscience Letters, 731, 135057.
https://doi.org/10.1016/j.neulet.2020.135057
DIXON, W. J. 1980. Efficient analysis of experimental observations. Annual Review of Pharmacology and Toxicology, 20(1), 441-462. https://doi.org/10.1146/annurev.pa.20.040180.002301
FAHIM S, A., and ALWAN A, T., 2022. Effects of ketorolac, xylazine, and bupivacaine multimodal analgesia on goats. Archives of Razi Institute, 77(2), 661-668.
GIRARD, P., CHAUVIN, M., and VERLEYE, M., 2016. Nefopam analgesia and its role in multimodal analgesia: a review of preclinical and clinical studies. Clinical and Experimental Pharmacology and Physiology, 43(1), 3-12. https://doi.org/10.1111/1440-1681.12506
GIRARD, P., COPPÉ, M.-C., VERNIERS, D., PANSART, Y., and GILLARDIN, J.-M., 2006. Role of catecholamines and serotonin receptor subtypes in nefopam-induced antinociception. Pharmacological Research, 54(3), 195-202. https://doi.org/10.1016/j.phrs.2006.04.008          
HASAN, M. M. 2018. Evaluating the sedative and analgesic effects of xylazine and its interaction with chlorpromazine in chicks, 32(2),9-3. https://doi.org/10.33899/ijvs.2019.153871
KANDA, T., MIZOGUCHI, Y., FURUMOTO, K., SHIMIZU, Y., MAETA, N., and FURUKAWA, T., 2020. Effect of intramuscular medetomidine administration on tear flow in rats. Veterinary Sciences, 7(2), 42.https://doi.org/10.3390/vetsci7020042
KHALIL, K. A., MOUSA, Y. J., and ALZUBAIDY, M. H., 2022. Pharmacokinetic criteria of ketoprofen and its cyclooxygenase-2 inhibition in mice: influence of xylazine administration. Macedonian Veterinary Review, 46, 27-33. https://doi.org/10.2478/macvetrev-2022-0031
KIM, K. H., and ABDI, S., 2014. Rediscovery of nefopam for the treatment of neuropathic pain. The Korean Journal of Pain, 27(2), 103-111.https://doi.org/10.3344/kjp.2014.27.2.103
KUMAR, R., AAKANKSHA, A. K., VERMA, N. K., SAXENA, A. C., and HOQUE, M., 2020. Systemic effects and clinical application of dexmedetomidine. Pharma Innovation Journal, 9(11), 241-246.  https://doi.org/10.22271/tpi.2020.v9.i11d.5344
LI, J.-X. 2019. Combining opioids and non-opioids for pain management: current status. Neuropharmacology, 158, 107619. https://doi.org/10.1016/j.neuropharm.2019.04.025
LI, Q., ZHUANG, Q., GU, Y., DAI, C., GAO, X., WANG, X., WEN, H., LI, X., and ZHANG, Y., 2018. Enhanced analgesic effects of nefopam in combination with acetaminophen in rodents. Biomedical Reports, 8(2), 176-183. https://doi.org/10.3892/br.2017.1032
MAO, J. 2012. Current challenges in translational pain research. Trends in Pharmacological Sciences, 33(11), 568-573. https://doi.org/10.1016/j.tips.2012.08.001
MIRANDA, H. F., NORIEGA, V., ZANETTA, P., PRIETO, J. C., PRIETO-RAYO, J. C., ARANDA, N., and SIERRALTA, F., 2014. Isobolographic analysis of the opioid-opioid interactions in a tonic and a phasic mouse model of induced nociceptive pain. Journal of Biomedical Science, 21, 1-9. https://doi.org/10.1186/s12929-014-0062-6
MULLER, P. Y., and MILTON, M. N., 2012. The determination and interpretation of the therapeutic index in drug development. Nature Reviews Drug Discovery, 11(10), 751-761.https://doi.org/10.1038/nrd3801
NASER, A.S., ALBADRANY, Y., SHAABAN, K.A., 2020. Isobolographic analysis of analgesic interactions of silymarin with ketamine in mice. Journal of the Hellenic Veterinary Medical Society, 71(2), 2171–2178. https://doi.org/10.12681/jhvms.23653
O'NEILL, A., and LIRK, P., 2022. Multimodal analgesia. Anesthesiology Clinics, 40(3), 455-468.https://doi.org/10.1016/j.anclin.2022.04.002
PETROIANU, G. A., ALOUM, L., and ADEM, A., 2023. Neuropathic pain: Mechanisms and therapeutic strategies. Frontiers in Cell and Developmental Biology, 11(3), 1072629.https://doi.org/10.3389/fcell.2023.1072629
RAFFA, R. B., 2001. Pharmacology of oral combination analgesics: rational therapy for pain. Journal of Clinical Pharmacy and Therapeutics, 26(4), 257-264.https://doi.org/10.1046/j.1365-2710.2001.00355.x
RAI, A., MENG, H., WEINRIB, A., ENGELSAKIS, M., KUMBHARE, D., GROSMAN-RIMON, L., KATZ, J., and CLARKE, H., 2017. A review of adjunctive CNS medications used for the treatment of post-surgical pain. CNS Drugs, 31, 605-615.https://doi.org/10.1007/s40263-017-0440-1
RODGERS, R. J., and DALVI, A., 1997. Anxiety, defence and the elevated plus-maze. Neuroscience and Biobehavioral Reviews, 21(6), 801-810.https://doi.org/10.1016/S0149-7634(96)00058-9
SALARPOUR, M., SAKHAEE, E., SAMIMI, A. S., and AZARI, O., 2022. Comparative evaluation of the sedative and physiological effects of medetomidine alone and in combination with pethidine, morphine, tramadol, and methadone in goats. Veterinary Medicine and Science, 8(4), 1664-1670.https://doi.org/10.1002/vms3.806
SHABAN, K. A., HAMED, Z. S., and FARIS, G. A.-M., 2024. The effect of metoclopramide on the antinociceptive, locomotor and neurobehavioral effects of metamizole in mice. Macedonian veterinary review, 47(2), 159-166. https://doi.org/10.2478/macvetrev-2024-0027
SHABAN, K. A., IBRAHIM, M. H., and FARIS, G. A., 2020. Evaluation of the antinociceptive effect of xylazine and its interaction with metoclopramide in the acute pain model in mice. Iraqi Journal of Veterinary Sciences, 34(2). https://doi.org/10.33899/ijvs.2019.126070.1226
SINCLAIR, M. D. 2003. A review of the physiological effects of α2-agonists related to the clinical use of medetomidine in small animal practice. The Canadian Veterinary Journal, 44(11), 885.
SMITH, H., and ELLIOTT, J., 2001. Alpha2 receptors and agonists in pain management. Current Opinion in Anesthesiology, 14(5), 513-518.https://doi.org/10.1097/00001503-200110000-00009
TAQA, G.A., 2012. Synergism of the analgesic activities of tramadol with α2 adrenoreceptor agonist xylazine in mice. Iraqi Journal of Veterinary Sciences, 26(2), 109-113. https://doi.org/10.33899/ijvs.2012.67485
TALLARIDA, R. J. 2011. Quantitative methods for assessing drug synergism. Genes and Cancer, 2(11), 1003-1008. https://doi.org/10.1177/1947601912440575
TANEJA, A., DELLA PASQUA, O., and DANHOF, M., 2017. Challenges in translational drug research in neuropathic and inflammatory pain: the prerequisites for a new paradigm. European Journal of Clinical Pharmacology, 73, 1219-1236.https://doi.org/10.1007/s00228-017-2301-8
THANOON, A. I., and FARIS, G. A., 2023. Evaluation the combination of chlorpheniramine and tramadol at a level of thermal and visceral antinociceptive in a mouse acute pain model. Iraqi Journal of Veterinary Sciences, 37(3), 619-627. https://doi.org/10.33899/ijvs.2022.135562.2496
TICK, H., NIELSEN, A., PELLETIER, K. R., BONAKDAR, R., SIMMONS, S., GLICK, R., RATNER, E., LEMMON, R. L., WAYNE, P., and ZADOR, V., 2018. Evidence-based nonpharmacologic strategies for comprehensive pain care: the consortium pain task force white paper. Explore, 14(3), 177-211. https://doi.org/10.1016/j.explore.2018.02.001
VERLEYE, M., ANDRÉ, N., HEULARD, I., and GILLARDIN, J.-M., 2004. Nefopam blocks voltage-sensitive sodium channels and modulates glutamatergic transmission in rodents. Brain Research, 1013(2), 249-255.https://doi.org/10.1016/j.brainres.2004.04.035
VIRTANEN, R., SAVOLA, J.-M., SAANO, V., and NYMAN, L., 1988. Characterization of the selectivity, specificity and potency of medetomidine as an α2-adrenoceptor agonist. European Journal of Pharmacology, 150(1-2), 9-14https://doi.org/10.1016/0014-2999(88)90744-3
VRANKEN, J. H., 2009. Mechanisms and treatment of neuropathic pain. Central Nervous System Agents in Medicinal Chemistry, 9(1), 71-78. https://doi.org/10.2174/187152409787601932
YIN, Z.-Y., LI, L., CHU, S.-S., SUN, Q., MA, Z.-L., and GU, X.-P., 2016. Antinociceptive effects of dehydrocorydaline in mouse models of inflammatory pain involve the opioid receptor and inflammatory cytokines. Scientific Reports, 6(1), 27129.https://doi.org/10.1038/srep27129

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History

  • Receive Date: 28 May 2025
  • Revise Date: 16 June 2025
  • Accept Date: 26 June 2025

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