Experimental and clinical studies on the absorption and toxicity of cerium nitrate

Abstract

In this publication we present the results of three studies concerning the toxicity and absorption of cerium. In the first experimental study in rats, following the application of a 2.2 % solution of cerium nitrate on dorsal wounds for five weeks, delayed healing was demonstrated and histological examination revealed richly vascularized granulation tissue in which microcalcifications and foreign-body type giant cells were found. A high concentration of cerium was found in the liver. The second experimental study employing rat enterocytes demonstrated an immediate cellular toxicity after exposure to a 2.2% cerium nitrate solution. Correction of pH and/or osmolarity did not play a protective role. In the clinical evaluation, significant levels of cerium were found in six blood samples and four urinary specimens, following the application of a 2.2% cerium nitrate solution on burn wounds. Liver biopsies were performed in two cases. There were no abnormal histological findings, but cerium levels were elevated.The first report of the use of cerium nitrate for the treatment of severely burned patients was published in 1976 by Monafo [22]. A review of the literature since that time revealed that the use of this substance has become increasingly popular but the reported results are widely divergent. Some authors have recorded improved survival rates for severely burned patients treated with cerium and have attributed this to its wide spectrum anti-bacterial effect associated with a state of improved immunity [3,12,13,17,19,20,21,25,26,33,35,36,40,41]. Others published less positive results and felt that the improved survival rates were due to better global management of the patient rather than the cerium therapy [5, Correspondence to. W. Raffoul, Service de Chirurgie Plastique et Centre de Brfil6s, CHUV, CH-1011 Lausanne, Switzerland -6, 11, 26, 23, 32]. Moreover, very little has been reported on its toxic effects and those results which do exist have been contradictory. Monafo did not find any trace of cerium in the blood and urine specimens of burned patients treated with cerium [7,25,27]. On the contrary, Hirakawa found significant quantities of cerium in hepatic biopsies [15]. Because of these conflicting reports, the study to be reported was performed to investigate the possible toxicity of topically applied cerium nitrate. In order to investigate this problem, two types of experimental studies were performed on rats in order to investigate the possible local and toxic effects of a 2.2% solution of cerium nitrate. In addition to these studies, a clinical evaluation of the use of cerium nitrate in severely burned patients was carried out. The results obtained are presented and discussed in this paper. Material and methods Experimental study IIn order to investigate the effects of cerium mtrate on dorsal skin wounds, sixteen female Wistar rats weighing between 200-220 g were divided into two experimental groups. Each animal was kept m a metabolic cage under identical conditions of light, temperature, humidity and noise...