906     LEAD POISONING- COTTER
J.A.MA, July 3, 1954

TREATMENT OF LEAD POISONING
BY CHELATION 

Lawrence H. Cotter, M.D., New York

Chelating agents have been used in industry for some time. The substance under consideration here, ethylene diamine tetra-acetic acid, with the structural formula shown in the figure, has proved valuable for recovering trace metals from foods and beverages and rare metals in analyzing solutions. Pathologists find it useful in decalcifying bone, and Gellhorn and others have used it clinically in reducing hypercalcemia. The effects of the calcium chelate on the excretion and storage of lead were studied by Rubin in his experiments on rabbits. Many other animal studies have been reported, and it is in fairly general use by veterinarians. Busman, Reid and Rubin reported a case in 1952 in which lead encephalopathy in a human being was successfully treated by intravenous injection of calcium disodium Versenate. The same year Belknap obtained excellent results in three cases with the same treatment. Popovici and associates found that the chelating agent was absorbed through the skin in human beings with resultant diminution of the serum calcium. The practicability of oral administration was, therefore, established, but there remained the danger of eliminating the normal plasma electrolytes coincidentally with lead. The recent development of a disodium calcium salt of the amino acid (Versene) made treatment possible without this disadvantage. It further proved to be pleasant to take, whereas all patients had complained of the persistent nauseating taste of the acid. The method employee in this series was to give a test dose of 25mg of Versene by mouth. If no allergic symptoms were observed at the end of 24 hours, the initial dose was repeated every 2 hours during the day until a total of 2gm had been given. This was continued for a week, by which time the patient had received 14gm. There were no complaints, and most of the patients volunteered the information that they felt an urge to urinate about 15 minutes after taking the pills.


                                          HOOC-CH2                                  CH2-COOH

N-CH2-CH2-N
 

                                          HOOC-CH2                                  CH2-COOH

 

From the Department of Medicine, Columbia University, College of Physicians and surgeons, and Presbyterian Hospital.
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Pharmacology, Physiology, Biochemistry and Toxicity of Versenes, Framingham, MASS, Bersworth Chemical co, Sept 19, 1952
Birge, E.A. and Imhoff, C.E.: Versenate as Decalcifying Agent for Bone, Am. J. Clin. Path. 22:192, 1952. Hahn, F.L., and Reygadas, F; Demineralization of Hard Tissues, Science 114;462, 1951
Gellhorn, A: Personal communication to author.
Rubin, M: Gignac, S, and Popovici, A: Effect of Calcium Verseante on Storage and Excretion of Lead in Rabbits, abstracted, J. Am. Chem.. Soc. 121:3J, 1952.
Holm, L.W.: Wheat, J.D.; Rhode, E.A.; and Firch, G: Treatment of Chronic Lead Poisoning in Horses with Calcium disodium Ethylenediaminetetraacetate, J. am. Bet. M.A. 123:38, 1953.
Bessman, S.P: Reid, H, and Rubin, M: Treatment of Lead Encephalopathy with Calcium Disodium Versenate: Report of Case, M. Ann, District of Columbia 21:312, 1952.
Belknap, E.L: EDTA in Treatment of Lead Poisoning, Indust. Med. 21:305, 1952.
Popovici, A; Geschickter, C.F; Reinovsky, A and Rubin, M: Experimental Control of Serum Calcium Levels in Vivo, Proc. Soc. Exper. Biol. & Med. 74:415, 1950.
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