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Tramadol has a better potency ratio relative to morphine in neuropathic than in nociceptive pain models.
Drugs R D. 2007; 8(1):51-7.DR

Abstract

BACKGROUND AND OBJECTIVE

Treatment of neuropathic pain remains a challenge and the role of various analgesics in this setting is still debated. The effects of tramadol, an atypically acting analgesic with a combined opioid and monoaminergic mechanism of action, and morphine, a prototypical opioid, were tested in rat models of neuropathic and nociceptive pain.

METHODS

Cold allodynia and mechanical hypersensitivity, symptoms of neuropathic pain, were studied in rat models of mononeuropathic pain. Cold allodynia was analyzed in the chronic constriction injury (CCI) model and mechanical hypersensitivity was analyzed in the spinal nerve ligation (SNL) model. Heat-induced rat tail-flick latencies were determined as measure for nociceptive pain.

RESULTS

Cold allodynia and mechanical hypersensitivity were strongly attenuated with similar absolute potency after intravenous administration of tramadol and morphine. The doses of drug that were calculated to result in 50% pain inhibition (ED(50)) for tramadol and morphine were 2.1 and 0.9 mg/kg, respectively, in CCI rats and 4.3 and 3.7 mg/kg, respectively, in SNL rats. In the tail-flick assay of acute nociception, the potency of the two drugs differed markedly, as seen by ED(50) values of 5.5 and 0.7 mg/kg intravenously for tramadol and morphine, respectively. Accordingly, the analgesic potency ratio (ED(50) tramadol/ED(50) morphine) of both compounds differed in neuropathic (potency ratio 2.3 in CCI and 1.2 in SNL) and nociceptive pain models (potency ratio 7.8), suggesting a relative increase in potency of tramadol in neuropathic pain compared with nociceptive pain.

CONCLUSION

The results of this study are consistent with clinical data supporting the efficacy of opioids in neuropathic pain conditions, and furthermore suggest an additional contribution of the monoaminergic mechanism of tramadol in the treatment of neuropathic pain states.

Authors+Show Affiliations

Biomedical Research, Grünenthal GmbH, Aachen, Germany.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17249849

Citation

Christoph, Thomas, et al. "Tramadol Has a Better Potency Ratio Relative to Morphine in Neuropathic Than in Nociceptive Pain Models." Drugs in R&D, vol. 8, no. 1, 2007, pp. 51-7.
Christoph T, Kögel B, Strassburger W, et al. Tramadol has a better potency ratio relative to morphine in neuropathic than in nociceptive pain models. Drugs R D. 2007;8(1):51-7.
Christoph, T., Kögel, B., Strassburger, W., & Schug, S. A. (2007). Tramadol has a better potency ratio relative to morphine in neuropathic than in nociceptive pain models. Drugs in R&D, 8(1), 51-7.
Christoph T, et al. Tramadol Has a Better Potency Ratio Relative to Morphine in Neuropathic Than in Nociceptive Pain Models. Drugs R D. 2007;8(1):51-7. PubMed PMID: 17249849.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Tramadol has a better potency ratio relative to morphine in neuropathic than in nociceptive pain models. AU - Christoph,Thomas, AU - Kögel,Babette, AU - Strassburger,Wolfgang, AU - Schug,Stephan A, PY - 2007/1/26/pubmed PY - 2007/6/19/medline PY - 2007/1/26/entrez SP - 51 EP - 7 JF - Drugs in R&D JO - Drugs R D VL - 8 IS - 1 N2 - BACKGROUND AND OBJECTIVE: Treatment of neuropathic pain remains a challenge and the role of various analgesics in this setting is still debated. The effects of tramadol, an atypically acting analgesic with a combined opioid and monoaminergic mechanism of action, and morphine, a prototypical opioid, were tested in rat models of neuropathic and nociceptive pain. METHODS: Cold allodynia and mechanical hypersensitivity, symptoms of neuropathic pain, were studied in rat models of mononeuropathic pain. Cold allodynia was analyzed in the chronic constriction injury (CCI) model and mechanical hypersensitivity was analyzed in the spinal nerve ligation (SNL) model. Heat-induced rat tail-flick latencies were determined as measure for nociceptive pain. RESULTS: Cold allodynia and mechanical hypersensitivity were strongly attenuated with similar absolute potency after intravenous administration of tramadol and morphine. The doses of drug that were calculated to result in 50% pain inhibition (ED(50)) for tramadol and morphine were 2.1 and 0.9 mg/kg, respectively, in CCI rats and 4.3 and 3.7 mg/kg, respectively, in SNL rats. In the tail-flick assay of acute nociception, the potency of the two drugs differed markedly, as seen by ED(50) values of 5.5 and 0.7 mg/kg intravenously for tramadol and morphine, respectively. Accordingly, the analgesic potency ratio (ED(50) tramadol/ED(50) morphine) of both compounds differed in neuropathic (potency ratio 2.3 in CCI and 1.2 in SNL) and nociceptive pain models (potency ratio 7.8), suggesting a relative increase in potency of tramadol in neuropathic pain compared with nociceptive pain. CONCLUSION: The results of this study are consistent with clinical data supporting the efficacy of opioids in neuropathic pain conditions, and furthermore suggest an additional contribution of the monoaminergic mechanism of tramadol in the treatment of neuropathic pain states. SN - 1174-5886 UR - https://www.unboundmedicine.com/medline/citation/17249849/Tramadol_has_a_better_potency_ratio_relative_to_morphine_in_neuropathic_than_in_nociceptive_pain_models_ L2 - http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=17249849.ui DB - PRIME DP - Unbound Medicine ER -