DefinePK

Abstract

The rapid induction of dependency is the priority of injection methods, but high mortality rate due to medullary depression is the most important limitation of injection methods in laboratory animals. This study was carried out on 5 groups of adult male wistar rats weighing 250-350 g which were maintained in standard light and temperature with free access to food and water. Four methods in which morphine dependency was achieved during a 5 days period were chosen and the mortality rate and the time of mortality were compared with the new group which received morphine (10 mg kg-1 on the first day and 20 mg kg-1 from 2nd to 5th day). Precipitation of Morphine withdrawal signs was performed on the 5th days, 4 h after the last injection of morphine and withdrawal signs were recorded in 5 min intervals for 20 min. The results of this study showed that the new modified method is an effective method for induction of morphine dependency. The least mortality rate (19%) was observed in the new modified morphine dependency method. Mortality rate in other procedures were ranged from 33-60%. The results of this study showed that first dose of morphine as well as the pattern of increasing dosage regimen are important factors which determine mortality rate. So we propose that this new method would be suitable for rapid induction of morphine dependency.