The pharmacology of ganglion blocking agents / by W.D.M. Paton.

  • William Paton
Date:
[1959?]
Catalogue details

Licence: In copyright

Credit: The pharmacology of ganglion blocking agents / by W.D.M. Paton. Source: Wellcome Collection.

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    drugs characteristically produce headache, and they have a peripheral dila¬ tor mechanism. I feel that there is a component of hydralazine’s action which involves histamine release, but of course it’s so mixed that it’s rather difficult to disentangle. Dr. Schroeder: I agree with Dr. Paton on that. As a matter of fact, when we give it to patients for the first time it looks as though the patients have got too much histamine in them and they even get a flu-like syndrome with pains in the back and stuffy nose and so on. Their rings get tight, they have edema without weight gain, their eyes are puffy, they flush, and many things hap¬ pen that suggest histamine release. But to my knowledge, histamine is a vasoconstrictor, isn’t it? Dr. Paton: That depends enormously on the person. The Pharmacology of Ganglion Blocking Agents W. D. M. PATON Royal College of Surgeons, England THE ACTIONS OF HEXAMETHONIUM AND PENTOLINIUM It is hardly necessary to describe in detail the experiments on which our views of the action of drugs like hexamethonium and pentolinium are based. It is generally agreed that drugs of this type act simply by an ability to com¬ pete with acetylcholine at the cholinergic synapse of autonomic ganglia. They are themselves unable to excite the ganglion, but if the synapse is ac¬ tive, they reduce the efficiency of the transmission. Since the antagonism is competitive, the intensity of the block, i.e., the proportion of cells for which synaptic transmission fails, steadily increases as the concentration of hexa¬ methonium or pentolinium in the extracellular space of the ganglion in¬ creases in relation to the acetylcholine released. This type of action can be extraordinarily selective. For practical purposes, ganglia only are affected and the response of peripheral effector organs to stimulants is unimpaired. Because these are quaternary salts, they must exist in solution as ions; that is, they have to carry about a positive charge with them, which greatly hinders their passage through cell walls. This gives them the other proper¬ ties, not directly to do with ganglion block, of being excluded from the cen¬ tral nervous system, of being poorly absorbed by mouth, of ^reaching a concentration in the plasma such as is to be expected if they lead an extracel¬ lular life, and of being filtered by the kidney, neither being reabsorbed nor actively secreted. All this makes a tolerably coherent picture. The specificity found for these drugs in the laboratory has been fully justified in clinical