Intravenous injection of leconotide, an omega conotoxin : synergistic antihyperalgesic effects with morphine in a rat model of bone cancer pain

Kolosov, Anton, Aurini, Lucia, Williams, Elizabeth D., Cooke, Ian, & Goodchild, Colin S. (2011) Intravenous injection of leconotide, an omega conotoxin : synergistic antihyperalgesic effects with morphine in a rat model of bone cancer pain. Pain Medicine, 12(6), pp. 923-941.

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Abstract

Objective.  Leconotide (CVID, AM336, CNSB004) is an omega conopeptide similar to ziconotide, which blocks voltage sensitive calcium channels. However, unlike ziconotide, which must be administered intrathecally, leconotide can be given intravenously because it is less toxic. This study investigated the antihyperalgesic potency of leconotide given intravenously alone and in combinations with morphine-administered intraperitoneally, in a rat model of bone cancer pain.

Design.  Syngeneic rat prostate cancer cells AT3B-1 were injected into one tibia of male Wistar rats. The tumor expanded within the bone causing hyperalgesia to heat applied to the ipsilateral hind paw. Measurements were made of the maximum dose (MD) of morphine and leconotide given alone and in combinations that caused no effect in an open-field activity monitor, rotarod, and blood pressure and heart rate measurements. Paw withdrawal thresholds from noxious heat were measured. Dose response curves for morphine (0.312–5.0 mg/kg intraperitoneal) and leconotide (0.002–200 µg/kg intravenous) given alone were plotted and responses compared with those caused by morphine and leconotide in combinations.

Results.  Leconotide caused minimal antihyperalgesic effects when administered alone. Morphine given alone intraperitoneally caused dose-related antihyperalgesic effects (ED50 = 2.40 ± 1.24 mg/kg), which were increased by coadministration of leconotide 20 µg/kg (morphine ED50 = 0.16 ± 1.30 mg/kg); 0.2 µg/kg (morphine ED50 = 0.39 ± 1.27 mg/kg); and 0.02 µg/kg (morphine ED50 = 1.24 ± 1.30 mg/kg).

Conclusions.  Leconotide caused a significant increase in reversal by morphine of the bone cancer-induced hyperalgesia without increasing the side effect profile of either drug.

Clinical Implication.  Translation into clinical practice of the method of analgesia described here will improve the quantity and quality of analgesia in patients with bone metastases. The use of an ordinary parenteral route for administration of the calcium channel blocker (leconotide) at low dose opens up the technique to large numbers of patients who could not have an intrathecal catheter for drug administration. Furthermore, the potentiating synergistic effect with morphine on hyperalgesia without increased side effects will lead to greater analgesia with improved quality of life.

Impact and interest:

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18 citations in Web of Science®

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ID Code: 77749
Item Type: Journal Article
Refereed: Yes
Keywords: Leconotide, Omega Conotoxin, Synergistic Antihyperalgesic effects, morphine, bone cancer pain, w-Conopeptide, Ca2+-Channels;, Hyperalgesia, intravenous injection, synergy
DOI: 10.1111/j.1526-4637.2011.01118.x
ISSN: 1526-2375
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > ONCOLOGY AND CARCINOGENESIS (111200) > Cancer Therapy (excl. Chemotherapy and Radiation Therapy) (111204)
Divisions: Current > Schools > School of Biomedical Sciences
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2011 Wiley Periodicals, Inc.
Deposited On: 16 Oct 2014 06:36
Last Modified: 17 Oct 2014 04:05

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