Comparison of five incubation systems for rat liver slices using functional and viability parameters.

Precision-cut liver slices are presently used for various research objects, e.g. to study metabolism, transport, and toxicity of xenobiotics. Various incubation systems are presently employed, but a systematic comparison between these incubation systems with respect to preservation of slice function has not been performed yet. Therefore, we started a comparative study to evaluate five of these systems: the shaken flask (an Erlenmeyer in a shaking water bath), the stirred-well (24-well culture plate equipped with grids and magnetic stirrers), rocker platform (6-well culture plate with Netwell insert rocked on a platform), the roller system (dynamic organ culture rolled on an insert in a glass vial), and the 6-well shaker (6-well culture plate in a shaking water bath). The liver slices were incubated in these incubation systems for 0.5, 1.5, and 24.5 h and subsequently subjected to viability and metabolic function tests. The viability of the incubated liver slices was evaluated by: potassium content, MTT assay, energy charge, histomorphology, and LDH leakage. Their metabolic functions were studied by determination of the metabolism of lidocaine, testosterone, and antipyrine. Up to 1.5 h of incubation all five incubation systems gave similar results with respect to viability and metabolic function of the liver slices. However, after 24 h, the shaken flask, the rocker platform, and the 6-well shaker incubation systems appeared to be superior to the stirred well and the roller incubation systems.

Rabbit model for estimating relative bioavailability, residues and tissue tolerance of intramuscular products: comparison of two ampicillin products.

A rabbit model for simultaneous investigation of the bioavailability, tissue residues and tissue tolerance of intramuscularly administered veterinary medicines is described. The bioavailability of ampicillin from two intramuscular products, which had been found to be different in calves, were compared in a two-way crossover design. The ampicillin levels in plasma, ampicillin residues in tissues, the plasma creatine kinase activity and the tissue damage at the injection sites were studied. The absolute bioavailabilities for the products were 100% and 40%. Differences in pharmacokinetics of ampicillin between sexes were observed after intravenous and intramuscular administration. Only slight tissue damage could be detected at the injection sites after intramuscular administration of these products. The results were compared with those obtained previously in calves and were found to be similar. Further investigations with other intramuscular drug products to validate this model are under way.

Determination of the heroin metabolite 6-acetylmorphine by high-performance liquid chromatography using automated pre-column derivatization and fluorescence detection.

An improved method for the determination of 6-acetylmorphine in the urine of drug addicts receiving morphine was developed. A newly introduced reversed-phase high-performance liquid chromatographic system proved to be more sensitive than a normal-phase system used previously. By replacing the earlier manual derivatization procedure with an automated on-line pre-column method, both the reproducibility and efficiency were considerably improved. Coefficients of variation for repeated analyses typically ranged from 6 to 10% in the 1-100 micrograms/l concentration range. The detection limit was 1 microgram/l and the correction for recovery by calibration with blank urine samples spiked with 6-acetylmorphine was satisfactory. The analytical improvements achieved, however, did not increase the chance of detecting heroin use by drug addicts.