The use of edathamil (Versene or EDTA) in the treatment of lead poisoning has received wide attention during the past few years. No new method of treatment of this disease has shown so much promise. The principle of its action is quite simple. The edathamil combines with the lead ions in the body to for un-ionized lead edathamil, a substance which, though it contains lead, shows practically none of the chemical properties of lead and therefore may be considered, for practical purposes, to be a nontoxic form of this metal. Moreover, the lead edathamil is very readily excreted in the urine.

The first use of edathamil for lead intoxication was by intravenous injection. Some spectacular results were obtained on the excretion of lead, with urinary lead levels up to 20mg per liter being obtained without any exacerbation of the symptoms.^1,2 It is obviously, however, much simpler to administer a drug by ingestion, particularly since, in the case of edathamil, relatively larger volumes of the solution must be introduced in the intravenous injection. Experiments on the efficiency of orally administered edathamil carried out by Foreman and Trujillo, using radioactive carbon as a tracer, indicated that only a relatively small amount of the orally ingested edathamil was absorbed, because only about 3% could be recovered in the urine.³

In a preliminary experiment two members of our laboratory treated themselves orally with edathamil by taking, over a period of four days, a total of about 10gm of the calcium disodium salt. The urine samples were collected each day while the drug was being taken and a few days after the end of the treatment and were analyzed for their lead content by an ashing method. The results are given in Figure 1.

It can be seen that the lead excretion is increased during the first few days of treatment but rapidly falls off when edathamil is discontinued. In Subject A the maximum lead excretion of 0.47mg per liter corresponds approximately to the concentration found in control subjects after a single intravenous injection if edathamil.¹

The lead excretion results found in the case of Subject B, although not as remarkable, also indicate and elevated lead excretion.

Both of our subjects began treating themselves with edathamil calcium disodium tablets at noon on the first day and continued doing so at meal times and prior to retiring until noon on the firth day. Urine samples were collected each day about 5 p.m.