Effect of opiate analgesia and opioid blockade on urethral mucosal sensitivity threshold.

The effect of opiate analgesics (omnopon, pethidine, pentazocine) on the urethral mucosal sensitivity threshold in 37 patients, and of the potent opiate/opioid antagonist naloxone on 10 volunteers is described. Omnopon and pentazocine caused a significant decrease in sensitivity (p less than 0.02) and naloxone caused a significant increase in sensitivity (p less than 0.02). The results confirm a role for the endogenous opioids in modulating urethral sensitivity, and the implications of this are discussed.