A global pharmaceutical company initiative: an evidence-based approach to define the upper limit of body weight loss in short term toxicity studies.

Short term toxicity studies are conducted in animals to provide information on major adverse effects typically at the maximum tolerated dose (MTD). Such studies are important from a scientific and ethical perspective as they are used to make decisions on progression of potential candidate drugs, and to set dose levels for subsequent regulatory studies. The MTD is usually determined by parameters such as clinical signs, reductions in body weight and food consumption.

Assessment of Labrasol/Labrafil/Transcutol (4/4/2, v/v/v) as a non-clinical vehicle for poorly water-soluble compounds after 4-week oral toxicity study in Wistar rats.

Drug safety research is frequently faced with the challenge of the selection of appropriate vehicles for use in in vivo non-clinical safety assessment studies. Reported here are the results of blend Labrasol, Labrafil and Transcutol, [L/L/T, (4/4/2, v/v/v)], excipients used as bioavailability enhancer and solubilizer for poorly water-soluble compounds and tested daily for 4 weeks by oral route in Wistar rats (10/sex/group) at dose volumes of 5, 10 or 20 mL/kg/day and compared to controls given 20 mL/kg/day of 1% (w/v) hydroxyethylcellulose in purified water. L/L/T was broadly well tolerated at 5 mL/kg/day and lethal at 20 mL/kg/day in 1 of 20 rats treated at this level.

Comparative effects of drugs on P-glycoprotein expression and activity using rat and human trophoblast models.

The drug efflux transporter P-glycoprotein (P-gp) is an active component of the placental barrier which protects the fetus against maternal xenobiotics. The goal of the study was to compare species difference between human and rat in terms of susceptibility to drugs at the level of the placental barrier using in vitro models in order to improve translation from rat to human. Effects of selected drugs (Aspirin, Methadone, a Cardiovascular Proprietary Compound, Thalidomide) on cytotoxicity and P-gp expression and activity were compared using human and rat trophoblast cultures.

Development and characterisation of a new model of rat trophoblasts.

The placenta plays a key role during pregnancy. In vitro models have proven to assess the role of placental transporters in the exchange of nutrients, waste products and the distribution of drugs between the maternal and fetal compartments. Therefore, a primoculture of Wistar rat trophoblasts from the labyrinth zone was developed and characterised.

A European pharmaceutical company initiative challenging the regulatory requirement for acute toxicity studies in pharmaceutical drug development.

Regulatory guidelines indicate acute toxicity studies in animals are considered necessary for pharmaceuticals intended for human use. This is the only study type where lethality is mentioned as an endpoint. The studies are carried out, usually in rodents, to support marketing of new drugs and to identify the minimum lethal dose.

Genetic toxicity assessment: employing the best science for human safety evaluation part IV: a strategy in genotoxicity testing in drug development: some examples.

The minimal three-test battery of the International Conference on Harmonization guideline has been in use since 1997 for the development of new pharmaceuticals (ICH, 1997). After a 10-year experience of this core battery in regulatory genotoxicity testing, everywhere the time has come for reflection about what was learned from this experience. Different aspects of genotoxicity testing are currently being debated under different organizations (HESI, 2006; IWGT, 2007; Kirkland et al.

Genetic toxicity assessment: employing the best science for human safety evaluation. Part II: Performances of the in vitro micronucleus test compared to the mouse lymphoma assay and the in vitro chromosome aberration assay.

The in vitro micronucleus test is commonly used in the early stages of pharmaceutical development as a predictive tool for the regulatory mouse lymphoma assay or in vitro chromosome aberration test. The accumulated data from this assay leads to the suggestion that it could be used as an alternative to the chromosome aberration test or the mouse lymphoma assay in the regulatory genotoxicity battery. In this paper, we present the results of the in vitro micronucleus test on L5178Y mouse lymphoma cells with 25 compounds from Servier research and have compared these results to those obtained in the genotoxicity regulatory battery.

Value of in vitro models for the assessment of drug-induced haematotoxicity.

Background: A new antipsychotic compound induced unexpected red cell hypoplasia (reticulocytopenia, red marrow hypoplasia) in rats dosed orally for 7 days.

Materials And Methods: Since an erythropoietin-mediated pathogenesis was excluded, in vitro tests on rat and human bone marrow cells were performed with measurement of formation of late erythroid (CFU-E) and granulocyte-macrophage (CFU-GM) colony-forming units after incubation with the drug. CFU-E together with growth factors were cultured for 2 days (rat) or 7 days (human) and CFU-GM was cultured for 7 days (rat) or 10 days (human).

Easy Procedure for Milk Collection in Lactating Rats.

Procedures have been developed for easy collection of milk samples without oxytocin injection. Dams were separated from their pups for 24 h, then were hand-milked with or without aspiration. During the lactation period, the collected milk volume increased up to day 10 of lactation, reached a plateau between days 10 and 18 (range, 2.

Cataractogenesis in rats induced by in utero exposure to RG 12915, a 5-HT3 antagonist.

RG 12915, a selective 5-HT3 antagonist developed for the treatment of emesis and nausea associated with cancer chemotherapy, was administered by gavage to four groups of pregnant rats from Gestation Day 6 to 17 at doses of 0, 1, 10, and 100 mg/kg/day, as part of a Segment II (developmental toxicity) study. The 100 mg/kg/day dose was maternally toxic as indicated by decreased body weight gain and food consumption during the treatment period. A portion of the rats were allowed to deliver and rear their litters and three pups from two litters in the 100 mg/kg/day group were observed to have lens opacities (visible to the naked eye) at weaning.

Anionic sites of the basement membrane of rat seminiferous tubules during ontogenesis.

The anionic sites of the basement membrane of rat seminiferous tubules were demonstrated ultrastructurally in the lamina densa by using cationic polyethyleneimine (PEI). The sites were largely digested out after incubation with heparitinase, indicating a large proportion of heparan sulfates. The anionic sites were present as early as day 16 of gestation on the interstitial side of the lamina densa, and after gestation day 20 they were symmetrically organized on both sides of the lamina densa.

Anionic sites in the basement membrane of the rat epididymal epithelium during ontogenesis and after testicular and gonadal tract lesions.

Anionic binding sites in the lamina densa of the basement membrane of the rat epididymal epithelium were demonstrated ultrastructurally with the use of cationized polyethyleneimine (PEI). Enzyme digestion with heparitinase removed the anionic sites, indicating that they consist largely of heparan sulfates. The anionic sites are present as early as the 16th day of gestation on the interstitial face of the lamina densa; later during gestation they are localized on both faces of the lamina densa without further modification after birth.

[Postnatal development of zinc levels in the epididymis and testis in rats under normal and experimental conditions].

Postnatal testicular and epididymal zinc concentration in the rat was investigated by means of differential pulse polarography. The zinc concentration increased gradually from birth to day 90 in the testis and up to day 60-90 in the epididymis with an abrupt increase on day 21. No marked variation in the zinc content was observed all along the epididymal duct.

[Ultrastructural analysis of anionic sites of the basal membrane of the seminiferous tubules of subjects with severe oligospermia].

Several morphological alterations of the basement membrane of the seminiferous tubules have been reported in the patients presenting with a testicular sterility. The proteoglycans are one of the major components of the basal membrane and may be ultrastructurally defined by the use of the cationic marker polyethyleneimine (PEI). In comparaison to the normal distribution of the anionic sites labelled by PEI which is characterized by a regular pattern of distribution along both the epithelial and the interstitial faces of the lamina densa, the pattern of distribution of the sites is largely altered in 6 patients, 27 to 40 years of age, with oligo- or azoospermia.

Ultrastructural study of epithelial cells and basement membrane. Differentiation of the rat epididymis after prenatal irradiation.

The effects of prenatal irradiation on the testis are well documented, but less is known about its effects on epididymal differentiation. Pregnant rats were irradiated on the 18th day of gestation. The increase in microfilaments and lipid inclusions in the epithelial cells, in favor of a direct radiation effect, is maximal at birth and disappears thereafter.

Influence of testicular secretions on differentiation in the rat epididymis: ultrastructural studies after castration, efferent duct ligation and cryptorchidism.

The differentiation of the rat epididymis was studied in prepubertal castrated, ligated or cryptorchid rats, in order to assess the influences of blood-borne and luminal androgens. The principal cells showed partial differentiation: decrease in cell height, decreased numbers of cytoplasmic organelles implicated in the elaboration phenomena (Golgi apparatus, smooth endoplasmic reticulum), whereas the organelles implicated in the absorptive function remained relatively intact. The lamina densa of the basement membrane underlying the epithelium was irregular, thicker than normal and followed the irregular outline of the basal parts of the epithelial cells.

Influence of testicular secretions on epididymis oxidative metabolism in the rat.

The oxidative metabolism of the epididymis has been investigated in 40-day-old rats under normal and experimental conditions. No difference in the oxidative metabolism was observed between the initial, middle and terminal segments of the epididymal duct of normal rats. After bilateral or unilateral castration or efferent duct ligation, the oxidative metabolism was found to be exclusively dependent upon plasmatic androgens in the terminal segment in contrast to the proximal segment oxidative metabolism which is dependent of both normal luminal secretions and normal plasmatic androgens.

Differentiation of the rat epididymis after withdrawal of androgen.

The differentiation capacity of the rat epididymis after depletion of androgen was studied in organ culture and in castrated rats. The differentiation of "narrow cells' in 5- and 10-day-old explants and in 10-day-old castrated rats suggests that: (i) the testicular androgens are not essential for their differentiation, (ii) a differential androgen dependence exists among the epididymal cell types, (iii) the undifferentiated epithelial cells are the precursors of the narrow cells.

[Postnatal development of oxidative metabolism of the epididymis in rats].

The oxidative metabolism of the epididymis decreases significantly from birth to 12 days and increases gradually after 20 days. Its evolution is contemporary with the development of the interstitial gland and follows the variations of plasmatic and tissular testosterone levels.

In vitro development of seminiferous tubules from immature rat testis: ultrastructural and morphometric studies.

Seminiferous tubules from 5 day-old rats maintained in a semi-solid culture system were examined for 4, 8 or 12 days. Morphometric and ultrastructural studies show a significant increase in the seminiferous tubule diameter and normal Sertoli cell differentiation. All the germinal cells degenerate except the spermatogonia.

Experimental synovitis induced by aluminium phosphate in rabbits. Comparison of the changes produced in synovial tissue and in articular cartilage by aluminium phosphate, carrageenin, calcium hydrogen phosphate dihydrate, and natural diamond powder.

The goal of this experimental study was to examine the effect on articular tissue of tribasic aluminium phosphate (crystalline and amorphous forms) after intraarticular injection in rabbit and to compare it with that of various phlogistic compounds such as carrageenin, calcium hydrogen phosphate dihydrate and diamond powder, as a control. Synovium and cartilage were studied with light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive micro-analysis (EDM). Crystalline and amorphous aluminium phosphate could induce a synovitis with articular effusion in rabbits.

[Toxicity and pharmacokinetics of zirconium oxychloride in mice and rats].

The experimental toxicity of zirconium compounds is examined in the Mouse (acute toxicity) and in the Rat (short time toxicity). The absorption, the distribution and the elimination of zirconium are evaluated by zirconium cation assay in some biological fluids and tissues. After a single oral dose, zirconium oxyd is not toxic, zirconium oxychlorure slightly toxic and zirconium chlorure moderately toxic.

Inflammatory effect of aluminium phosphate on rat paws.

The aim of this experiment was to determine the inflammatory effect of aluminium phosphate on the rat paw and to compare it with those of carrageenan, calcium hydrogen phosphate dihydrate and natural diamond powder. At the probability threshold of the various tests used there was a significant increase in volume of the treated paw relative to the control paw for all the substances at all times, except for the two concentrations of diamond (effect no longer significant from 30 min on), of calcium phosphate (not significant from 2 h), and of aluminium phosphate (not significant from 24 h). The effects were not significantly different between diamond and calcium phosphate (both concentrations).