Whole-body tissue distribution of total radioactivity in rats after oral administration of [¹⁴C]-bilastine

Abstract

This study evaluated the tissue distribution of total radioactivity in male albino, male pigmented, and time-mated female albino rats after oral administration of a single dose of [¹⁴C]-bilastine (20 mg/kg). Although only 1 animal was analyzed at each time point, there were apparent differences in bilastine distribution. Radioactivity was distributed to only a few tissues at low levels in male rats, whereas distribution was more extensive and at higher levels in female rats. This may be a simple sex-related difference. In each group and at each time point, concentrations of radioactivity were high in the liver and kidney, reflecting the role of these organs in the elimination process. In male albino rats, no radioactivity was measurable by 72 hours postdose. In male pigmented rats, only the eye and uveal tract had measurable levels of radioactivity at 24 hours. Measureable levels of radioactivity were retained in these tissues at the final sampling time point (336 hours postdose), indicating a degree of melanin-associated binding. In time-mated female rats, but not in albino or pigmented male rats, there was evidence of low-level passage of radioactivity across the placental barrier into fetal tissues as well as low-level transfer of radioactivity into the brain.

Keywords::

• antihistamines
• autoradiography
• bilastine
• tissue distribution

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Erratum

Acknowledgments

The authors thank Dr Aurelio Orjales as the director of research at Faes Farma during the development of these studies. The authors thank Steve Clissold, PhD, Content Ed Net, for his editorial assistance, which was funded by Faes Farma.

Declaration of interest

M.L.L. is an employee of Faes Farma, S.A., and A.B.P. is an employee of Charles River Laboratories. The authors have no conflicts of interest that are directly relevant to the content of this study.