Morphine perfused rabbits: A tool for experiments in forensic entomotoxicology

In order to establish an animal model for entomotoxicological studies, the kinetics of morphine elimination from blood after a single intravenous inje ction of morphine and the concentrations of morphine in tissues following a continuous perfusion were studied. The aim of these experiments was to obt ain controlled morphine tissue concentrations similar to those encountered in fatal human heroin overdoses. These tissues can be used as a food source for developing fly larvae in entomotoxicological studies. In the single in jection experiment. seven rabbits were administered 1 or 2 mg/kg body weigh t of morphine chlorhydrate via the main ear artery, Blood samples of 200 mu L were removed regularly via a catheter. Morphine concentration was determ ined using RIA techniques, Morphine was found to be first rapidly distribut ed and then slowly eliminated, following a two-exponential equation. Elimin ation of morphine from blood can be described as a two-compartment model. C onstants of the equation were determined using the Kaleidagraph(R) program. Using those constants, the main pharmacokinetics parameters were calculate d. Results of these parameters showed the following: clearance from 13.3 to 16.2 L.h-1, half-life of the distribution phase from 0.6 to 0.9 min, and h alf-life of the elimination phase from 21 to 26 min. These results were use d to calculate the rate of perfusion of morphine for rabbits to obtain desi red, controlled, and constant concentrations of morphine in tissues. In the second experiment, three rabbits received a perfusion of morphine intravas cularly at a rate of 2 mg/kg/h for a period of 3 h These rabbits were sacri ficed and analyses performed on several abdominal and thoracic organs. Resu lts showed that the concentrations of morphine differed according to the or gan analyzed, but were reproducible for organs between animals. These conce ntrations were similar to those normally encountered in cases of human deat h due to heroin overdoses.