Central analgesic activity of ibuprofen. A neurophysiological study in humans.

Ibuprofen is a widely used non-steroidal anti-inflammatory drug (NSAID). Inhibition of prostaglandin biosynthesis is considered to be the main mechanism of action of this substance. Recently, a central analgesic activity was described in an experimental study. In order to explore the possibility that ibuprofen induces analgesia at central level in humans, we investigated, in a double-blind design, the effects of orally-given 600 mg granular ibuprofen or placebo on nociceptive flexion reflex in normal volunteers. Ibuprofen produced a significant increase, as compared to placebo, in the threshold of the nociceptive reflex. The ratio between subjective pain threshold (Tp) and reflex threshold (Tr) was unchanged after either ibuprofen or placebo administration, indicating that Tp strictly paralleled Tr. These results indicate that ibuprofen displays a central antalgic activity in humans. Different supraspinal structures are probably involved, but the exact mechanisms are still to be clarified.