Lee A, et al. - By performing this randomized double-blind trial, researchers investigated whether clonidine vs fentanyl, added to bupivacaine, would afford an effective option for treating breakthrough pain during labor. Randomization to a 10 mL bolus solution comprising 12.5 mg bupivacaine and either clonidine 100 μg or fentanyl 100 μg was done in 98 term parturients receiving bupivacaine 0.0625% 12 mL/h with fentanyl 2 μg/mL, a patient-administered bolus of 5 mL at lockout 6-10 min and a maximum of four boluses per hour, and suffering from breakthrough pain ≥ 5/10. Findings revealed the non-superiority of epidural clonidine 100 μg vs fentanyl 100 μg in terms of reducing pain scores within 15 min of co-administration with bupivacaine 0.125% for intrapartum breakthrough pain. No significant differences were observed in terms of analgesic efficacy and hemodynamic side effects.