MECHANISM OF LONG DURATION OF ACTION OF DIBENZYLINE’

There are two hypotheses to explain the mechanism of long duration of action of Dibenamine and its congener Dibenzyline. One is that the adrenergic blocking action of these drugs involves destruction or prolonged inactivation of some cellular substance necessary for the excitatory response to epinephrine and that the blockade persists until the substance is regenerated (Nickerson and Goodman, 1948; Nickerson, 1949.) The other is that the persistence of blockade is due to the storage of the drug in fat, from where it slowly diffuses into the blood and tissues and exerts its blocking effects in extremely low concentrations (Brodie, Aronow and Axelrod, 1954; Axelrod, Aronow and Brodie, 1952). The present study was undertaken to explore the role of fat depots in the main-tenance of the adrenergic blockade by Dibenzyline. METHODS. Localization of Dibenzyline block in the hind limb of the cat. Cats of either sex weighing from 2 to 3 kgm. were anesthetized with thiopental sodium (40 mgm./ml.), given slowly intravenously through an indwelling needle over the period of the operation, which lasted approximately 45 minutes. The femoral vessels were isolated and cleared from th