Venlafaxine and oxycodone have different effects on spinal and supraspinal activity in man: a somatosensory evoked potential study

Dina Lelic, Massimiliano Valeriani, Iben W D Fischer, Albert Dahan, Asbjørn M Drewes

Research output: Contribution to journalArticlepeer-review


AIMS: Opioids and antidepressants that inhibit serotonin and norepinephrine reuptake (SNRI) are recognized as analgesics to treat severe and moderate pain, but their mechanisms of action in humans remain unclear. The present study aimed to explore how oxycodone (an opioid) and venlafaxine (an SNRI) modulate spinal and supraspinal sensory processing.

METHODS: Twenty volunteers were included in a randomized, double-blinded, three-way (placebo, oxycodone, venlafaxine), crossover study. Spinal and full scalp cortical evoked potentials (EPs) to median nerve stimulation were recorded before and after 5 days of treatment. Assessment of the central effects of the three treatments involved: (i) amplitudes and latencies of spinal EPs (spinal level); (ii) amplitudes and latencies of the P14 potential (subcortical level); (iii) amplitudes and latencies of early and late cortical EPs (cortical level); (iv) brain sources underlying early cortical Eps; and (v) brain networks underlying the late cortical EPs.

RESULTS: In the venlafaxine arm, the spinal P11 and the late cortical N60-80 latencies were reduced by 1.8% [95% confidence interval (CI) 1.7%, 1.9%) and 5.7% (95% CI 5.3%, 6.1%), whereas the early cortical P25 amplitude was decreased by 7.1% (95%CI 6.1%, 8.7%). Oxycodone increased the subcortical P14 [+25% (95% CI 22.2%, 28.6%)], early cortical N30 [+12.9% (95% CI 12.5%, 13.2%)] amplitudes and the late cortical N60-80 latency [+2.9% (95% CI 1.9%, 4.0%)]. The brainstem and primary somatosensory cortex source strengths were increased by 66.7% (95% CI 62.5%, 75.0%) and 28.8% (95% CI 27.5%, 29.6%) in the oxycodone arm, whereas the primary somatosensory cortex strength was decreased in the venlafaxine arm by 18.3% (95% CI 12.0%, 28.1%).

CONCLUSIONS: Opioids and SNRI drugs exert different central effects. The present study contributed to the much-needed human models of the mechanisms of action of drugs with effects on the central nervous system.

Original languageEnglish
Pages (from-to)764-776
Number of pages13
JournalBritish Journal of Clinical Pharmacology
Issue number4
Publication statusPublished - Nov 3 2016


  • Journal Article


Dive into the research topics of 'Venlafaxine and oxycodone have different effects on spinal and supraspinal activity in man: a somatosensory evoked potential study'. Together they form a unique fingerprint.

Cite this