Effect of microsampling (50 μL) on toxicological evaluation of methapyrilene, a hepatotoxic substance, in a collaborative 28-day study in female rats

Abstract

Although microsampling of blood is recommended to promote the 3Rs in toxicokinetic (TK) evaluation, there are few reports applying microsampling in actual toxicity evaluation. Here, we assessed the effects of microsampling on toxicological evaluation of methapyrilene hydrochloride, a hepatotoxic substance. Female SD rats received methapyrilene hydrochloride orally at dose levels of 0 (vehicle), 10, and 30 mg/kg BW, once daily for 4 weeks. Each dose level included a microsampling group and a non-microsampling group (n = 5). In the microsampling groups, blood sampling (50 µL/time point) was performed at 6 time points on day 1 of administration and 7 time points on day 27-28; all the animals underwent necropsy on day 29. Toxicity studies and TK analysis were performed, and through these studies in 2 organizations, cross-organization validation of the effect on toxicity evaluation was conducted. In one organization, microsampling obscured changes in some parameters in hematology due to the administration of methapyrilene hydrochloride. In the other organization, although the relationship between the developing pattern of histopathological findings in the liver and the blood sampling was suspected, it was associated with poor reproducibility; this was considered as a change within a variation range of biological reactions. Each of these phenomena was observed in only one organization without consistency. In both organizations, no effect of blood microsampling was observed in other endpoints. In conclusion, microsampling is considered to be a technique applicable to safety studies of drugs showing hepatotoxicity, as it did not show a marked influence on the toxicological evaluation of methapyrilene hydrochloride.

Impact of microsampling on toxicological evaluation in rodent safety studies

“…For drugs with other than hematological toxicity, the effects of microsampling on toxicological evaluation of methapyrilene hydrochloride, as a model compound for hepatotoxic drug, were evaluated (Hattori et al, 2023). Female SD rats received methapyrilene hydrochloride orally at dose levels of 0 (vehicle) and two dosage levels for 4 weeks at two organizations.…”

“…With regard to blood sampling from animals treated with drugs, there are no reports of blood sampling from the tail vein. Meanwhile, when blood was collected from the jugular vein, all previous reports have set the 24‐h blood collection volume to mostly less than 3% of the circulating blood volume (Hattori et al, 2023; Ohtsuka et al, 2022; Tanaka et al, 2023; Tochitani et al, 2022). Since the toxicological effects of blood sampling were minimal in all reports (although the potential influence on certain parameters might not be fully excluded in their statistical significance of the changes), the amount of blood collected from drug‐treated animals should be less than 3% of the circulating blood volume.…”

The 3Rs in Experimental Liver Disease

“…Other routes that have been shown to induce acceptable levels of distress when applied to serial sampling are the lateral tail vein [205] and the saphenous vein [204]. Although there is still research to be done given the novelty of this field, the use of serial microsampling has a promising niche in the study of DILI [209].…”