Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 41 2 2003 06 15 134 137 Sadeghi SA Soleimani AA Soleimanifar M 2015 09 28 It has been sugeested since long that peripheral nerves possess opiod receptors and this has tempted clinicans in adding narcotics to local anesthetics to prolong the analgesic effects of these solutions. In this regard, we studied 45 patients undergoing surgical procedures on upper extremities. The patients scheduled for surgery were divided in to three groups, each comprising of 15 patients and all the patients underwent supraclavicular block. In goup A, we used 5 mg/kg of 1.5 percent lidocaine, in group B the same dose of lidocaine along with 1 mcg/kg of fentanyl solution was use. Lidocaine in the above dosage and pethidine 1mg/kg were injected to the patients in group C to facilitate supraclavicular block. The average length of analgesia was 180 minutes in group A, 300 minutes in group B and 406 minutes in group C. In conclusion: Adding pethidine or fentanyl to local anesthetics can increase the analgesia period 2-3 times. Although pethidine implies longer effect than fentanyl, but this difference is not significant (P>0.05). https://acta.tums.ac.ir/index.php/acta/article/view/2650 https://acta.tums.ac.ir/index.php/acta/article/download/2650/2632