The Anticoagulant Effects in Rabbits and Man of the Intravenous Injection of Salts of the Rare Earths.

The recent interest in the anticoagulant action of heparin has led us to seek a substance which might be similar in action but less expensive and simpler to administer. The anticoagulant effect of various rare earths given intravenously has been studied in lower animals (1, 2, 3). As far back as 1920, Esnault and Brou (4), and Grenet and Drouin (5) injected rare earths in 40 to 100 mgm. doses intravenously into human subjects, as therapeutic agents in tuberculosis. More recently, Dyckerhoff and Goossens (6) found that neodymium salts injected intravenously prolonged (considerably) the coagulation time of the blood of dogs and man. These authors gave some 30 injections to human subjects, the total dosage of neodymium salt varying from 250 to 500 mgm. The anticoagulant action persisted for as long as 6 hours after a single injection, and no ill effects were noted. No anticoagulant effects resulted from the oral or subcutaneous administration of neodymium. The need for a cheaper and more easily administered anticoagulating agent than heparin, led us to study the anticoagulant properties of rare earths. The experimental data which we obtained on animals justified an attempt to observe the effects of these substances in man. Our experience, which does not support the claims of Dyckerhoff and Goossens that they are harmless to man, is the subject of this report.