Determination of drug levels in larvae of Lucilia sericata (Diptera : Calliphoridae) reared on rabbit carcasses containing morphine

This study concerns the determinations of morphine concentrations in fly la rvae reared on rabbits administered different concentrations of morphine an d a correlation between concentrations of the drug in larvae and tissues. T hree rabbits (R1, R2 and R3) were given dosages of 12.5, 25.0 and 50.0 mg/h of morphine over a 3 h period via continuous ear artery perfusion. These d osages and time of perfusion were calculated to create tissue concentration s of morphine similar to those encountered in human deaths due to overdose. Morphine blood level plateau was attained after 1 h of perfusion. A Fourth rabbit was used as a control. To evaluate drug concentrations, tissues wer e sampled using a coelioscopic technique: Approximately 400 eggs of Lucilia sericata, all of the same age category, were placed in eyes, nostrils and mouth of each rabbit carcass.,larvae and puparia were regularly collected f rom each rabbit for toxicological analysis. The concentrations of the drug in the tissues sampled were determined to be similar to those normally enco untered in human overdoses and were correlated with the dosage of morphine that had been administered. Morphine was detected in all larvae and pupae f ed on tissues from carcasses administered morphine, except for puparia from the colony fed on the R1 animal which received 12.5 mg/h dosage of morphin e. All samples from the control rabbit were negative for morphine. Concentr ations of morphine in larvae reared on rabbit carcasses containing morphine were 30 to 100 times lower than the concentrations found in the tissues.. A correlation between the tissue concentrations and larval concentrations:w as found in only 3rd instar larvae (80 to 140 h following hatching). No cor relations were found between administered dosages, tissue concentrations an d younger larvae, prepuparial larvae or puparia.