Generic UPLC-MS/MS and Gyrolab assays with blood microsampling for pharmacokinetic assessments of therapeutic antibodies in mice.

Serial blood sampling from one animal is useful to understand relationship between pharmacokinetics (PK) and pharmacological or toxicological events in individual animals. To assess its feasibility in mice, two therapeutic antibodies were used to evaluate impacts by different blood sampling methods, sampling sites, and assay platforms on PK. Denosumab and Panitumumab were intravenously administered to mice and only 0.05 mL of blood sample per point was collected from jugular vein or tail vein. Blood samples were collected serially from a mouse or collected by traditional composite sampling from each mouse. Plasma concentrations of the two drugs were assayed by a generic ligand binding assay using Gyrolab or by a generic ultra-performance liquid chromatography with tandem mass spectrometry. The two assay platforms showed acceptable accuracy and precision and gave comparable PK parameters of the drugs, suggesting that both assays were successfully applied to the PK assessments. Comparable results in the PK profiles were noted between serial and composite blood samplings and differences in the two sampling sites did not impact PK. These findings suggest that microsampling combined with generic assays is useful to assess PK profiles of therapeutic antibodies in mice.

Quantitative and qualitative application of a novel capillary microsampling device, Microsampling Wing™ (MSW), using antiepileptic drugs in rats.

A novel microsampling device, namely, the Microsampling Wing™ (MSW), was evaluated using three anti-epileptic drugs (AEDs): carbamazepine, lamotrigine, and phenytoin. A simultaneous assay method of the three AEDs was developed and qualified via liquid chromatography with tandem mass spectrometry. Using 2.8 µL plasma, the three AEDs were quantifiable from 1 or 2 ng/mL. According to the intra-assay reproducibility assessment and additional validation parameters, the established method is reproducible. To apply the device to a pharmacokinetic (PK) study in rats, a cocktail of the three AEDs was orally administered to rats. Whole blood samples were serially collected using the MSW device and a glass capillary from the tail vein, and plasma samples (each 2.8 µL) from each device were assayed to compare PK parameters. The PK parameters of the three AEDs were similar between the two devices. A metabolite identification study was also conducted after oral administration of carbamazepine to rats. At least seven metabolites were detected in plasma, and the major metabolite was carbamazepine 10,11-epoxide, which is in accordance with the reported results. These findings suggest that the MSW device is a useful microsampling device for PK and metabolite identification studies.

Study for collecting background data on Wistar Hannover [Crl:WI(Han)] rats in embryo-fetal development studies--comparative data to Sprague Dawley rats.

The purpose of the present study was to collect the background data on Wistar Hannover [Crl:WI(Han)] (hereafter Wistar Han) rats in embryo-fetal development studies from the 6 safety research facilities of pharmaceutical companies and contract research organizations. In each facility, 20 or 22 female rats were dosed with vehicle solution during the organogenesis period. As a result, no abnormalities in clinical signs and necropsy findings in dams were found. Body weights and food consumption in dams were lower than those in Sprague Dawley (SD) rats. The number of corpora lutea (13.3 vs. 16.0 in SD) and implantations (11.8 vs. 14.7) were fewer, and fetal body weights (3.66 vs. 3.70) and placental weights (0.42 vs. 0.45) tended to be lower than those in SD rats. Regarding the fetal abnormalities, the incidence of several findings such as the persistent left umbilical artery (10.4% vs. 1.1%) and cervical (5.2% vs. 0.4%), full (7.4% vs. 0.9%) or short supernumerary (64.5% vs. 9.9%) and wavy ribs (6.6% vs. 0.3%) was higher than that in SD rats. Our present study showed that they maintained a sufficient number of live fetuses and the difference in the fetal sex ratio was not observed. In conclusion, Wistar Han rats were considered to be a suitable strain for embryo-fetal development toxicity study. Since the incidence of several abnormalities was higher than that in SD rats, it may be said that to accumulate background control data is important to evaluate the embryo-fetal development toxicity study using Wistar Han rats.

Historical control data on prenatal developmental toxicity studies in rabbits.

Historical control data on rabbit prenatal developmental toxicity studies, performed between 1994-2010, were obtained from 20 laboratories, including 11 pharmaceutical and chemical companies and nine contract laboratories, in Japan. In this paper, data were incorporated from a laboratory if the information was based on 10 studies or more. Japanese White rabbits and New Zealand White rabbits were used for prenatal developmental toxicity studies. The data included maternal reproductive findings at terminal cesarean sections and fetal findings including spontaneous incidences of morphological alterations. No noticeable differences between strains or laboratories were observed in the maternal reproductive and fetal developmental data. The inter-laboratory variations in the incidences of fetal external, visceral, and skeletal alterations seem to be due to differences in the selection of observation parameters, observation criteria, and classification of the findings, and terminology of fetal alterations.

Involvement of neurokinin receptors in the control of pulsatile luteinizing hormone secretion in rats.

It has recently been shown that neurokinin B, a tachykinin, is associated with GnRH pulse generation in sheep and goats. The aim of the present study was to clarify the role of tachykinin receptors in the control of LH secretion in rats. To this end, we evaluated the effect of CS-003, an antagonist for all three neurokinin receptors (NK1, NK2 and NK3 receptors), on pulsatile LH secretion in both sexes of rats with different routes of administration. Both oral and third ventricular administration of CS-003 suppressed LH secretion in both sexes of gonadectomized animals. Furthermore, intact male rats with oral administration of CS-003 showed decreased serum testosterone levels, which might be due to suppressed LH secretion. None of the three subtype-specific neurokinin receptor antagonists showed a significant effect on LH secretion in ovariectomized rats when each antagonist was singly administered. The present results suggest that neurokinins play a role in the control of pulsatile GnRH/LH secretion via multiple neurokinin receptors in both male and female rats.

Testicular toxicity induced by a triple neurokinin receptor antagonist in male dogs.

Mechanism mediating the testicular toxicity induced by CS-003, a triple neurokinin receptor antagonist, was investigated in male dogs. Daily CS-003 administrations showed testicular toxicity, such as a decrease in the sperm number, motility and prostate weight; and an increase in sperm abnormality, accompanying histopathological changes in the testis, epididymis and prostate. A single CS-003 administration suppressed plasma testosterone and LH levels in intact and castrated males. The suppressed LH release was restored by GnRH agonist injection, suggesting that pituitary sensitivity to GnRH is not impaired by CS-003. Treatment with SB223412, a neurokinin 3 receptor antagonist, caused a similar effect to CS-003, such as toxicity in the testis, prostate and epididymis and decreased plasma level of LH and testosterone. In conclusion, CS-003-induced testicular toxicity is caused by the inhibition of neurokinin B/neurokinin 3 receptor signaling probably at the hypothalamic level in male dogs.