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Dextromethorphan potentiates morphine antinociception at the spinal level in rats
Lok-Hi Chow1, Eagle Y-K Huang, Shung-Tai Ho
1Graduate Institute of Medical Science, Department of Pharmacology, National Defense Medical Center, Tapei, Taiwan.
Canadian Journal of Anaesthesia = Journal Canadien D'Anesthesie
|November 5, 2004
Summary
Dextromethorphan enhances morphine
Area of Science:
- Pharmacology
- Neuroscience
- Pain Management
Background:
- Morphine is an effective analgesic, but its use is limited by adverse effects.
- Dextromethorphan (DM) can potentiate morphine's analgesic effects and reduce required doses.
- The mechanism of DM's potentiation of morphine analgesia is not fully understood.
Purpose of the Study:
- To investigate the role of spinal N-methyl-D-aspartate (NMDA) receptors in dextromethorphan's potentiation of morphine antinociception.
- To exclude pharmacokinetic interactions by administering drugs at the spinal level.
Main Methods:
- Rats were used to test antinociceptive effects via the tail-flick test.
- The NMDA channel was blocked using MK-801.
- Interactions between intrathecal (i.t.) morphine and DM were studied.
Main Results:
- Dextromethorphan (DM) and MK-801 alone did not produce significant antinociception.
- DM significantly enhanced morphine's antinociceptive effect in a dose-dependent manner.
- Pretreatment with MK-801 potentiated morphine antinociception, and DM could not further enhance it.
Conclusions:
- Spinal NMDA receptors are crucial for dextromethorphan's potentiation of morphine antinociception.
- This finding suggests a potential mechanism for combining these drugs in pain management.