Pentamethonium and Hexamethonium Iodide in Vascular Disease and Hypertension
Authors: C. C. Burt, A. J. P. Graham
Journal: BMJ (1950)

The clinical potentialities of hexamethonium iodide (C6) in producing ganglionic block were first reported by Paton and Zaimis (1948a, 1948b), who stated that it possessed greater potency and longer duration of action than tetra- ethylammonium bromide (T.E.A.B.).Preliminary obser- vations of the effect of pentamethonium iodide (CS) in man were made by Organe, Paton, and Zaimis (1949).Clinical effects of C5 as a vasodilator were reported by Arnold and Rosenheim (1949) and by Arnold, Goetz, and Rosenheim (1949).At the request of the Medical Research Council we undertook an investigation of the clinical effects of C5 and C6 with a view to assessing their value in the routine inves-.tigation of peripheral vascular disease and hypertension, and to comparing these with reflex vasodilatation and with T.E.A.B. Methods Investigations were made on three groups of subjects: (a) 5 normal controls; (b) 15 patients with vasomotor disorders, including acrocyanosis, erythrocyanosis, hyper- hidrosis, and Raynaud's phenomenon without evidence of occlusive arterial disease; and (c) 7 patients with essential hypertension.Whenever practicable the subjects were given each of the drugs under trial on consecutive days, but the order in which these were given was varied; a few patients were investigated before and after operations on the sympathetic nervous system.The drugs were administered intravenously-C5 and C6 in doses of 30-40 mg.during one to two minutes, and T.E.A.B. in doses of 250-500 mg. in two to four minutes.Reflex vasodilatation tests were carried out by immersing one hand and one foot in a water-bath at 43.5°C.The subject, covered with two blankets, lay supine on a couch, with the trunk between 30 and 45 degrees above the horizontal and the lower limbs horizontal.The hands were 3 in. (7.6 cm.) above the sternal angle and the feet 9 in.(22.8 cm.) below.Room temperature varied between 17 and 22.50 C., but on any one day extremes did not exceed 1.5°C.The skin temperature.in upper and lower limbs was recorded by means of copper-constantan thermocouples attached to the nail-folds.Blood flow to hands or feet and to forearms or legs was measured by venous occlusion plethysmography, using air displacement (Barcroft and Walker, 1949).Skin colour, calibre of conjunctival and retinal vessels, and changes in nail-fold and digital-pad capillaries were noted before and after administration of the drugs.Sweating was measured by recording changes *A Report to the Medical Research Council.in skin resistance on the pads of fingers and toes.Record- ings were made at intervals of five minutes for 30 minutes before administration of the drug.After administration, recordings were made every one to two minutes for 10 minutes and then at five-minute intervals for periods of 60 to 90 minutes.Subjective sensations were also noted.In reflex vasodilatation tests, either skin temperature or blood flow recordings were made, because only two limbs were available for recording purposes. ResultsBlood Pressure 1.In Controls and Vasospastic Cases.-(a)Systolic pres- sure: Following administration of 30-40 mg. of C5 or C6, in all except one of the patients tested there occurred a slight fall in systolic pressure, which was of a similar extent in the case of both drugs.The average fall in this group was between 15 and 24 mm.Hg (Table I). (b) Diastolic TABLE I.-Average Blood-pressure Changes Average Time of Fall (in l4inutes) Average