Ketorolac exerts its analgesic effects at which part of the afferent pathway?

Ketorolac exerts its analgesic effects at which part of the afferent pathway?

• A. At the level of peripheral sensory receptors
• B. At the dorsal route ganglia
• C. At the spinal thalamic tract
• D. At the thalamus

Answer: (A)

The key idea is that ketorolac lowers the excitability of pain signals at their source. As an NSAID, it inhibits cyclooxygenase and decreases prostaglandin synthesis at injured tissue. Prostaglandins normally sensitize peripheral nociceptors, making them fire more readily in response to a stimulus. By reducing this peripheral sensitization, ketorolac reduces the initiation of nociceptive impulses at the peripheral sensory endings, so the analgesic effect occurs at the level of peripheral sensory receptors. It does not primarily act to block transmission at central sites like the dorsal root ganglion, spinal tracts, or thalamus, which would involve different mechanisms.

The key idea is that ketorolac lowers the excitability of pain signals at their source. As an NSAID, it inhibits cyclooxygenase and decreases prostaglandin synthesis at injured tissue. Prostaglandins normally sensitize peripheral nociceptors, making them fire more readily in response to a stimulus. By reducing this peripheral sensitization, ketorolac reduces the initiation of nociceptive impulses at the peripheral sensory endings, so the analgesic effect occurs at the level of peripheral sensory receptors. It does not primarily act to block transmission at central sites like the dorsal root ganglion, spinal tracts, or thalamus, which would involve different mechanisms.