The regional localisation of a new potent centrally acting antihypertensive agent R 28935 and its less active threo-isomer R29814 in the cat brain.

Systemic administration of the centrally acting antihypertensive agent R 28935 to cats resulted in a long lasting decrease of mean arterial pressure (+/-30%) whereas the same dose of the threo-isomer R 29814 was ineffective. The antihypertensive activity was due to the unaltered drug. In spite of an identical log P, pKa, dose and a comparable plasma level, the concentration of R 28935 in all the brain areas tested was about twice that of the threo-isomer, suggesting a stereoselective uptake and/or binding of R 28935.