succimer and Cadmium-Poisoning

Heavy metals are, unfortunately, present in the air, water, and food supply. Cases of severe acute lead, mercury, arsenic, and cadmium poisoning are rare; however, when they do occur an effective, non-toxic treatment is essential. In addition, chronic, low-level exposure to lead in the soil and in residues of lead-based paint, to mercury in the atmosphere, in dental amalgams and in seafood, and to cadmium and arsenic in the environment and in cigarette smoke is much more common than acute exposure. Meso-2,3-dimercaptosuccinic acid (DMSA) is a sulfhydryl-containing, water-soluble, non-toxic, orally-administered metal chelator which has been in use as an antidote to heavy metal toxicity since the 1950s. More recent clinical use and research substantiates this compound s efficacy and safety, and establishes it as the premier metal chelation compound, based on oral dosing, urinary excretion, and its safety characteristics compared to other chelating substances.

Topics: Arsenic Poisoning; Cadmium Poisoning; Chelating Agents; Heavy Metal Poisoning; Humans; Lead Poisoning; Mercury Poisoning; Poisoning; Succimer

Topics: Animals; Antidotes; Arsenic Poisoning; Biotransformation; Cadmium Poisoning; Dimercaprol; Forecasting; Humans; Kinetics; Lead Poisoning; Mercury Poisoning; Metals; Solubility; Succimer; Sulfhydryl Compounds; Unithiol

The influence of an antioxidant agent such as N-acetyl cysteine (NAC) or mannitol on the cadmium chelating ability of monoisoamyl 2,3-dimercaptosuccinate (MiADMS) was investigated in cadmium pre-exposed rats. This ester of 2,3-dimercaptosuccinic acid (DMSA), an accepted drug for lead poisoning, being lipophilic in nature was expected to be an efficient cadmium chelator. The treatment of cadmium intoxicated animals with MiADMS reversed cadmium induced increase in blood catalase, superoxide dismutase (SOD) and malondialdehyde (MDA), liver MDA and brain SOD and MDA levels but not the decrease in blood, liver brain reduced glutathione (GSH) and increase in oxidized glutathione (GSSG) levels, consistent with the lowering of tissue cadmium burden. The administration of NAC or mannitol reversed the cadmium induced alterations in blood and liver GSH, GSSG, blood catalase, SOD, MDA, liver SOD, MDA and brain MDA levels without lowering blood and tissue cadmium contents. However, treatments with the combination of MiADMS and NAC or MiADMS and mannitol reversed these alterations as well as reduced blood and tissue cadmium concentrations. The combined treatment with MiADMS and mannitol was better than that with MiADMS and NAC, and was significantly more effective in normalizing blood, liver GSH, GSSG, brain GSSG, and their GSH/GSSG ratios than that by either of them alone. The combined treatments also improved liver and brain endogenous zinc levels, which were decreased due to cadmium toxicity. The results suggest that the administration of an antioxidant during chelation of cadmium may provide beneficial effects by reducing oxidative stress without its cadmium removing ability.

Topics: Acetylcysteine; Administration, Oral; Animals; Antioxidants; Brain; Cadmium Chloride; Cadmium Poisoning; Catalase; Chelating Agents; Drug Synergism; Drug Therapy, Combination; Glutathione; Liver; Male; Malondialdehyde; Mannitol; Oxidative Stress; Rats; Succimer; Superoxide Dismutase

Topics: Arsenic Poisoning; Cadmium Poisoning; Chelating Agents; Humans; Lead Poisoning; Mercury Poisoning; Poisoning; Succimer

meso-2,3-Dimercaptosuccinic acid (DMSA) treatment in free of liposome-encapsulated form was given to mice pre-exposed to cadmium as CdCl2 (2 intraperitoneal injections; 0.5 mg Cd/kg along with 5 microCi 109CdCl2 in 4 ml volume within 24 h). Both treatments removed cadmium from liver, spleen, testis and blood with liposomal DMSA exhibiting higher efficacy in mobilizing cadmium not only from whole organs but also from liver proteins. It also resulted in higher excretion of cadmium via urine as compared with free DMSA or saline treatment. Whereas this treatment eliminated significantly higher amounts of cadmium via the fecal route throughout the period examined, free DMSA responded only 48 h after treatment and was less effective. The results suggest mobilization of cadmium from intracellular sites of deposition. However, DMSA in the dose administered (24 mumol/kg i.v.) in either form was ineffective in decorporating cadmium from the kidney, the critical organ in cadmium intoxication.

Topics: Animals; Cadmium; Cadmium Poisoning; Drug Carriers; Injections, Intraperitoneal; Liposomes; Male; Mice; Succimer; Tissue Distribution

Isolated hepatocytes appear to be a suitable in vitro model for the testing of the efficacy of chelating agents. In this study hepatocytes were isolated from rats exposed to CdCl2 (50 mg Cd2+/l) in drinking water for 3 months. The cells were incubated in a Krebs-Henseleit buffer for 2 hrs and the cytotoxicity was assessed using 5 types of parameters. N-benzyl-D-glucaminedithiocarbamate (BGDTC) and meso-2,3-dimercaptosuccinic acid (DMSA) were tested. Individual chelators in various concentrations were added to the incubation medium at the beginning of the experiment (t = 0). The concentration of Cd in the extracellular fluid was measured every 30 mins using flame AAS. Exposed hepatocytes did not show the signs of damage. Both chelators did not exhibit any cytotoxic effect. BGDTC was found to be efficient in the mobilization of Cd, while DMSA was ineffective.

Topics: Animals; Cadmium; Cadmium Poisoning; Cells, Cultured; Chelation Therapy; Liver; Rats; Rats, Inbred Strains; Sorbitol; Succimer; Thiocarbamates

Topics: Alkaline Phosphatase; Animals; Cadmium; Cadmium Poisoning; Copper; gamma-Glutamyltransferase; Kidney; Liposomes; Male; Rats; Succimer; Trace Elements; Zinc

An examination has been carried out on the relative efficacy of a number of chelating agents when acting as antagonists for oral cadmium chloride intoxication in mice. The compounds were administered orally after the oral administration of cadmium chloride at 1 mmol/kg. Of the compounds examined, several were useful in terms of enhancing survival, but by far the most effective in both enhancing survival and leaving minimal residual levels of cadmium in the liver and the kidney, was meso-2,3-dimercaptosuccinic acid (DMSA). Several polyaminocarboxylic acids also enhanced survival. The most effective of these in reducing liver and kidney levels of cadmium were diethylenetriaminepentaacetic acid (DTPA), trans-1,2-diaminocyclohexane-N,N,N'N'-tetraacetic acid (CDTA), and triethylenetetraminehexaacetic acid (TTHA). D-Penicillamine (DPA) was found to promote survival but also led to kidney cadmium levels higher than those found in the controls. Sodium 2,3-dimercaptopropane-1-sulfonate (DMPS) was as effective in promoting survival as DMSA but left levels of cadmium in the kidney and liver that were approximately four times greater than those found with DMSA.

Topics: Administration, Oral; Animals; Antidotes; Cadmium; Cadmium Chloride; Cadmium Poisoning; Chelating Agents; Edetic Acid; Male; Mice; Pentetic Acid; Succimer

The conditioned flavor-aversion paradigm was used to assess the toxicity of acutely administered cadmium and the interaction of cadmium with the heavy-metal chelating agents dimercaprol (BAL) and dimercaptosuccinic acid (DMSA). Shortly after consuming saccharin, rats received ip administration of cadmium either alone or in combination with sc administration of BAL or DMSA. Three days later they were given the choice between consuming saccharin or water, and saccharin preferences were recorded. When compared to rats receiving either nothing or the vehicle, rats receiving cadmium displayed significant reductions in saccharin preference (i.e., conditioned flavor aversions). BAL and DMSA were also capable of producing conditioned flavor aversions when given alone. Rats receiving cadmium in combination with either BAL or DMSA displayed significant, but not complete attenuations of conditioned flavor aversions when compared to the flavor aversions of rats receiving cadmium alone. Chelator-induced blockade of cadmium-induced flavor-aversion conditioning was not obtained when BAL or DMSA administration was delayed by 4 hr. Attenuation of cadmium-induced aversions by BAL and DMSA extends earlier findings of an attenuation of lead-induced flavor-aversion conditioning by these complexing agents, and thus demonstrates further the utility of the flavor-aversion conditioning paradigm in characterizing metal-chelator interactions.

Topics: Animals; Behavior, Animal; Body Weight; Cadmium Poisoning; Chelating Agents; Conditioning, Operant; Dimercaprol; Dose-Response Relationship, Drug; Male; Rats; Succimer; Taste; Time Factors

The antidotal efficacies of chelators during acute cadmium intoxication has previously been examined in experiments where both a soluble cadmium salt and the chelator were administered parenterally. In the present study, PA, DMSA and related compounds were studied as oral antidotes during oral CdCl2 intoxication. According to the antagonistic effects noted on mortality, peristaltic toxicity and intestinal cadmium uptake, the relative efficacies of the compounds tested were: DMSA greater than PAD greater than DMPS greater than MSA greater than PA greater than NAPA. None of the chelators induced major changes in the organ distribution of absorbed cadmium, in particular no increased cerebral deposition of cadmium. This study indicates that, in oral cadmium intoxication in humans, orally administered DMSA would be likely to offer protection against the local toxicity of cadmium in the gastrointestinal tract as well as to reduce the risk of systemic toxicity of absorbed cadmium.

Topics: Administration, Oral; Animals; Cadmium; Cadmium Chloride; Cadmium Poisoning; Cadmium Radioisotopes; Male; Mice; Penicillamine; Succimer; Sulfhydryl Compounds; Whole-Body Counting

Topics: Acute Disease; Animals; Cadmium; Cadmium Poisoning; Chelating Agents; Edetic Acid; Liver; Male; Metallothionein; Mice; Mice, Inbred Strains; Pentetic Acid; Succimer; Time Factors

Water soluble analogs of British Anti-Lewisite that are active orally and less toxic than BAL are now available. These agents are 2,3-dimercapto-1-propanesulfonic acid and meso-dimercaptosuccinic acid. Evidence for their effectiveness in preventing the lethal effects of sodium arsenite in mice and lewisite in rabbits is presented. These analogs can be expected to replace BAL in the treatment of heavy metal poisoning.

Topics: Animals; Arsenic Poisoning; Arsenites; Cadmium Poisoning; Chelating Agents; Dimercaprol; Lethal Dose 50; Male; Mice; Penicillamine; Sodium Compounds; Succimer; Sulfhydryl Compounds; Unithiol

Topics: Animals; Cadmium; Cadmium Poisoning; Chelating Agents; Edetic Acid; Male; Mice; Pentetic Acid; Succimer; Tissue Distribution

An examination has been made of the relative effectiveness of three chelating agents in reducing lethality in acute cadmium poisoning. The chelating agents used were sodium 2,3 dimercaptosulfonate (DMPS), N-Acetyl d,1 penicillamine (NAPA), and 2,3 dimercaptosuccinic acid (DMSA). For cadmium acetate administered ip at a level of 16.9 mg/kg, the oral administration of the chelating agents at a 20:1 mole ratio in three doses subsequent to the cadmium acetate at 20 minutes, 90 minutes, and 210 minutes resulted in a significant enhancement of the survival rate for all three compounds. At this level none of the control animals survived beyond 2 days. On the basis of the experiments carried out here the survival rates decreased in the order sodium 2,3 dimercaptopropane-sulfonate greater than 2,3 dimercaptosuccinic acid greater than N-Acetyl d,l penicillamine. In a study of the effect of the mole ratio of the chelating agent sodium 2,3 dimercaptopropanesulfonate to cadmium acetate on the survival rate, it was found that the survival rate attained a maximum for values between 20 and 60 and dropped off at both higher and lower values. It was also found that for at least one set of conditions, younger animals were better able to survive the administration of cadmium acetate and the antidote than older animals.

Topics: Animals; Antidotes; Cadmium Poisoning; Chelating Agents; Male; Mice; Mice, Inbred Strains; Penicillamine; Succimer; Sulfhydryl Compounds; Time Factors