Cholecyctectomy is one of the most painful operations that due to adjacent of incision site with chest cage reducing the pulmonary function and accompanied with its complication. Effective analgesia after operation reduces these alternation ,complications and improve patient’s outcome. The aim of this study was the comparison of the survey of effectiveness of interpleural bupivacaine and intramuscular opioid (methadone) in post
   cholecyctectomy analgesia.

This randomized clinical trial study was carried out in surgery wards of Ekbatan and Mobasher Kashani hospitals in Hamadan. 20 ASA I and II patients who were candidate for operation were selected into two groups, for IPB group 20cc of 0.25% bupivacaine was injected into interpleural space and for
   IMM group 70mg/kg methadone was injected intramuscular. The above drugs were repeated every 8hr with the same dosage for 48hr. 6 hours after the operation ABGwas repeated and severity of pain with VAS route was measured.

There was no statistical significant difference in sex and age between two assessed groups. Postoperative pulmonary function parameters such as vital capacity reduced in 2 groups and had lower change in IPB group and this difference was statistically significant (P=0.03). VAS in IPB group in 6, 24 and 48 hr post operatively was so lower than IMM group that had statistically difference
   (P=0.006). Patient satisfaction from analgesia was higher in IPB group in compare to IMM group. This difference was also statistically significant (P=0.004).

The results of this study showed that using interpleural analgesia in
   compare with intramuscular methadone for open cholecyctectomy pain were more satisfied and pulmonary function were protected better too.