Abuse potential of morphine/dextromethorphan combinations.

Area of Science:

• Pharmacology
• Neuroscience

Background:

• Morphine is a potent analgesic with a high potential for abuse.
• Dextromethorphan is known to potentiate morphine's pain-relieving effects.
• The potential for dextromethorphan to enhance morphine's abuse liability is a critical concern.

Purpose of the Study:

• To investigate whether dextromethorphan potentiates the abuse-related actions of morphine.
• To determine if dextromethorphan enhances the euphorigenic, physical dependence, or respiratory depressant effects of morphine.

Main Methods:

• Clinical pharmacology experiments were conducted.
• Evaluated the effects of dextromethorphan on morphine's euphorigenic and miotic actions.
• Assessed dextromethorphan's impact on naloxone-precipitated withdrawal responses.
• Measured the combined effects on morphine-induced respiratory depression.

Main Results:

• Dextromethorphan did not potentiate the euphorigenic or miotic effects of morphine.
• Morphine was found to suppress the dysphoric effects of dextromethorphan.
• Dextromethorphan did not alter responses to naloxone-precipitated withdrawal.
• No potentiation of morphine-induced respiratory depression was observed.

Conclusions:

• Dextromethorphan selectively potentiates morphine analgesia without enhancing its abuse potential.
• These findings suggest that combining dextromethorphan with morphine may offer improved pain relief with a reduced risk of abuse.
• The abuse liability of morphine is not increased by dextromethorphan.