Comparative studies on central factors contributing to the hypotensive action of propranolol, alprenolol, and their enantiomers

Abstract

The β-receptor blocking drugs, propranolol and alprenolol, and their dextrorotatory isomers were injected or infused into the vertebral artery of open-chest, anaesthetized cats and the hypotensive effects were compared to those obtained after injection or infusion of the same dose into a peripheral vein. Penetration of these drugs through the blood-brain barrier was studied by the assay of drug concentrations in plasma and cerebrospinal fluid. Propranolol probably lacks marked central hypotensive properties, whereas the blood pressure lowering effect of alprenolol was shown to possess a substantial central component.