IRCT2017051126866N3 IRCT 2017-06-11 Vice Chancellor for research of Isfahan University of Medical Sciences Effect of adding neostigmine and fentanyl to bupivacaine in caudal analgesia Comparison of the effect of neostigmine and fentanyl when added to bupivacaine in caudal analgesia in inguinal herniorrhaphy for children aged between 1 to 6 years double-blind clinical study 2017-05-31 anticipated 140 Complete https://irct.ir/trial/22162 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment, Other design features: using permuted block randomization method. N/A local aneasthetics. Patients were assigned, using permuted block randomization method, into four groups of 35. Children in the first group received a caudal injection of 0.5 ml/kg bupivacaine 0.25% plus fentanyl 1µ/kg. The second group received 0.5 ml/kg bupivacaine 0.25% plus neostigmine 1µ/kg. Patients in the third group received 0.5 ml/kg bupivacaine 0.25% plus combination of fentanyl 1µ/kg and neostigmine 1µ/kg, and those in the fourth group only received 0.5 ml/kg bupivacaine 0.25% concentration..