ABSTRACT
The most important use of neuromuscular blockers is as adjuvant to general anaesthesia where adequate muscle relaxation can be achieved at lighter plane. They also reduce reflex muscle contraction in the region undergoing surgery and assist maintenance of controlled ventilation during anaesthesia. They are particularly helpful in abdominal and thoracic surgery, intubations and endoscopies, orthopedic manipulation, etc. Thus, the risk of respiratory and cardiovascular depression is minimized, and post anesthetic recovery is shortened. The potency ratio of two commonly used neuromuscular agents depolarizing succinylcholine and non depolarizing pancuronium. Double pith a frog and fasten it to a frog board with ventral side up. The sternum was cut through just above the xiphisternum at its base and a pair of muscle attached to it were dissected out and transferred to a dish containing frog Ringer solution at room temperature. All the drug containing solutions were freshly prepared before the experiments Succinyl choline, Pancuronium (1,10,100mg/ml and 1mg/dl) respectively Acetyl choline (10,100mg/ml and 1mg/dl). Acetylcholine solution in various strength were prepared starting from 0.1% to 0.0001%.NMJ blocker Pancuronium was added to the biophase in addition to selected dose (128mg or 256mg) and the contraction of muscle till the 70-80% of inhibition is produced and the difference from sub maximal contractions. The median ED50 was interpolated from the figure taking 50%of inhibition from Height of contraction in mm. The ‘t’ test was performed to compare the ED50 value were interpolated from the regression line to find out the ED50 of the drug. The median doses (ED50) of both of them were calculated graphically and compared. The mean ED50 value of succinylcholine was found to be 1.59 ± 0.08μg (95% confidential limit was from 1.53 to 1.66μg). The ED50 of pancuronium was found to be 0.52 ± 0.10μg with 95% confidence limit being from 0.44 to 0.60μg. The ED50 value of the two drugs was very significantly different (P < 0.001). The potency ratio of pancuronium to succinylcholine was 0.32.
ABSTRACT
The animal models used in this study were Plexus anesthesia in frogs, Infiltration anesthesia in guinea pigs, Surface anesthesia in rabbits. The drugs were diluted with normal saline. Lignocaine2%: xylocaine hydrochloride injection IP, Bupivacaine 0.5%: Bupivacaine hydrochloride injections IP were prepared. Plexus anesthesia: Frog was pithed and spinal cord was destroyed up to the 3 vertebra. The abdominal pouch was filled with local anesthetic solution. Reflex activity was tested by immersing both feet of the frog every two minutes for not longer than 10 seconds into N/10 Hydrochloric acid. The time was noted. Surface anesthesia: Albino rabbits of either sex weighing 2.5 – 3.0kg ware selected. The conjunctival sac of one eye was held open, thus formed a pouch. 0.5ml of solution of the anesthetic was applied into the conjunctival sac for 30 sec. Infiltration anesthesia: Preparation of guinea pig: Guinea pigs (either sex) weighing 250-300grams were used. Lignocaine produced rapid onset of plexus anesthesia in Frogs in comparison to the bupivacaine at concentration of 0.1% & 0.2% which is statistically significant. Bupivacaine is more potent than the lignocaine as a surface anesthetic agent in the Rabbit, where as lignocaine could produce surface anesthesia at concentration of 0.5% or 0.1% or both. Both bupivacaine and lignocaine produced infiltration anesthesia on intradermal injection in guinea pigs but the duration of infiltration anesthesia produced by bupivacaine is more prolonged which is statistically significant in comparison to the lignocaine at all the three concentrations tested i.e. 0.05%, 0.1% & 0.2%.