Zinc-DTPA

Pentetate Calcium Trisodium ([calcium DTPA] and Pentetate Zinc Trisodium [zinc DTPA])... 

A. A radioactive material must be eliminated from the body to remove its hazard. Detoxification, which is effective against chemical hazards, will not be effective since radioactivity is not modified by chemical changes. The methods of elimination include renal excretion for most soluble materials, elimination in the feces for materials that are retained in the gut or which can be secreted in the bile, and exhalation for volatile materials and gases. Chelating agents, e.g., calcium or zinc DTPA (diethylenetriamine pentaacetic acid), if administered soon after exposure, are effective in enhancing the elimination of certain radioisotopes. These materials are not very effective for radioisotopes that have been incorporated and fixed in organs and tissues, e.g., bone. 

Calcium or zinc complexes of polycarboxylate compounds such as DTPA or ethylenediaminetetratacetic acid (EDTA) have been used as chelating agents to accelerate the urinary excretion of americium in humans who were accidentally exposed to americium (Breitenstein 1983 Doerfel and Oliveira 1989 ... 

Soils in the North China Plain and Loess Plateau regions contained 0.04-3.01 mg/kg DTPA-extractable Zn with an average of 0.44 mg/kg. The concentrations of DTPA-extractable Zn in northern China are presented in Table 7.7. In the loessial soils of the Loess Plateau, 64% of the soil samples had less than 0.5 mg/kg of bioavailable Zn. The bioavailable Zn in the arid soils of North China varied from 0.08-11.84 mg/kg with an average of 1 mg/kg, with 41% of the soil samples having < 0.5 mg/kg of bioavailable Zn. The average amount of bioavailable Zn in calcareous soils was 0.35 mg/kg (trace - 1.12 mg/kg). The North China Plain and Loess Plateau are major Zn-deficient regions in China. Calcareous paddy soils frequently displayed Zn deficiency in rice. Zinc fertilizers have been applied to rice, maize, sorghum, wheat, cotton and fruit trees where bioavailable Zn was less than 0.5 mg/kg. 

A common critical limit for Zn deficiency in soils has been 0.5 mg/kg DTPA-extractable Zn for different crops (maize, wheat, and rice) (Sillanpaa, 1982). DTPA-extractable Zn concentration of 0.5-1.0 mg/kg has been marginal for sensitive crops (Sillanpaa, 1982). Brown isohumic calcareous soils of New South Wales in Australia with 35-60 mg/kg of total Zn showed Zn deficiency due to the low bioavailability of Zn. Zinc deficiency has been reported to occur in wheat on solidized solonetz and solodic soils and other calcareous soils of South Australia. Zinc application at the rate of 0.6-28 kg/ha to cereals, pastures, and maize of Australia has been reported (Reuter, 1975). Zn deficiency occurs in Turkey, India, Iraq, Mexico, and Pakistan (Table 7.8). Zinc deficiency is frequently observed in rice on calcareous paddy soils. 

Lindsay W.L., Norvell W.A. Development of a DTPA soil test for zinc, iron, manganese, and copper. Soil Sci Soc Am J 1978 42 421 128. 

Sajwan K.S., Lindsay W.L. Effect of redox, zinc fertilization and incubation time on DTPA-extractable zinc, iron and manganese. Commun Soil Sci PlantAnal 1988 19 1-11. 

The method described below will use the complexing reagent DTPA (diethylene-triaminepentaacetic acid) to extract, by chelation, copper, iron, manganese and zinc (including zinc on calcareous soils) it also shows promise for monitoring cadmium, nickel and lead in soils receiving sludge appli-... 

Adams JF, Kissel DE. 1989. Zinc copper and nickel availabilities as determined by soil solution and DTPA extraction of a sludge-amended soil. Commun Soil Sci Plant Anal 20 139-158. 

The manifestations of the toxicity of DTPA arise from depletion of transition elements97. Administration of DTPA as its zinc salt suppresses its toxicity. Computer simulation studies of the chelates formed in plasma identify Zn-DTPA as the major form, 96%, whereas Ca-DTPA accounts for 3%91. ... 

Because the drug and the mobilized metals are excreted via the urine, the drug is contraindicated in anuric patients. Nephrotoxicity from EDTA has been reported, but in most cases this can be prevented by maintenance of adequate urine flow, avoidance of excessive doses, and limitation of a treatment course to 5 or fewer consecutive days. EDTA may result in temporary zinc depletion that is of uncertain clinical significance. An experimental analog of EDTA, calcium disodium diethylenetriaminepentaacetic acid (DTPA), has been used for removal ("decorporation") of uranium, plutonium, and other heavy radioisotopes from the body. 

Merkel, D. (1996). Cadmium, copper, nickel, lead and zinc contents of wheat grain and soils extracted with CaC /DTPA (CAD), CaCl2 and NH4NO3. Agribiological Research—Zeitschriji Fur Agrarhiolo-gie Agrikulturchemie Okologie 49, 30—37. 

Following exposure to plutonium, curium and americium, chelation with pentate calcium trisodium (CaDTPA), pentate zinc trisodium (Zn-DTPA), or dimercapto-propane-1-sulfonic acid (DMPS) can be administered (Chung Shannon, 2005). Ca-DTPA and Zn-DTPA chelate with metals and are excreted in the urine (Chung Shannon, 2005). These medications are administered by inhalation or intravenous routes at a dosage of 14 mg/kg IV, up to a maximum of 1 g (Chung Shannon, 2005). 

For treatment when acute nephrotoxicity is possible, alkalinization of the urine is important to increase urinary excretion of uranium. Systemic chelating agents, such as calcium or zinc salts of diethylenetria-minepentaacetic acid (Ca-DTPA or Zn-DTPA), although recommended in some publications, have not been shown to be useful in increasing the excretion of uranium. 

The concentration of (EDTA) ", and thus the ability to complex metal ions, will depend upon the pH. A decrease in pH results in an increase in the deprotonation of EDTA and hence an increase in the concentration of the ED I A ion. The effect of this is that only metal ions with a very high affinity for EDTA will be able to form stable complexes. The stability constants for the EDTA and [diethylenetriaminepentaacetic acid] - (DTPA ) complexes with some important metal ions that are of particular interest for chelation therapy are listed in Table 7.3. It is important to note that the stability of the EDTA and DTPA complexes with toxic metals, such as lead, mercury, cadmium, or plutonium are quite similar to those with essential metals such as zinc, cobalt or copper however, the Ca complex is many orders of magnitude lower. This has important implications for chelation therapy. First, the mobilization and excretion of zinc and other essential metals are likely to be increased, along with that of the toxic metal during EDTA treatment and secondly, the chelation of the ionic calcium in the blood, that can cause tetany and even death, can be avoided by administering the chelator as the calcium salt. 

Laurie, S. H., Tancock, N., McGrath, S. P., and Sanders, J. R. (1991). Influence of complexation on the uptake by plants of iron, manganese, copper and zinc effect of DTPA in a multi-metal and computer simulation study. J. Exp. Bot. 42, 509-513. 

Chelation by LMMO substances is a major factor in the transport of micronutrient cations such as Cu, Zn, Ni, Fe, and Mn to root surface by mass flow and diffusion. In soil solutions of calcareous soils 40 to 75% of tlie zinc and 98% of copper have been found in organic complexes (Hodgson et al., 1966 Sanders, 1982, 1983 McGrath et al., 1988). For plants the importance of complexed micronutrients in the soil solution is particularly evident in calcareous soils. This is also indicated by the fact that soil extractions with synthetic chelators such as EDTA and DTPA provide suitable soil tests for estimation of available micronutrieiits (Sims and Johnson, 1991) (summarized in detail in Section 11.3). 

Gough, L. P., McNeal, J. M., and Severson, R. C. (1980). Predicting native plant copper, iron, manganese and zinc levels using DTPA and EDTA soil extractants in northern Great Plains. Soil Sci. Soc. Am. J. 44, 1030—1036. 

The inability of DTPA to completely coordinate the tetra-valent actinides is shown by the easy formation of ternary complexes between Th(DTPA) and many bidentate ligands (16, 17, 18). The hydrolysis of Th(IV) and U(IV) DTPA complexes at pH near 8 is explained by the dissociation of H+ from a coordinated water molecule (19, 20, 21, 22). In addition, the polyaminocarboxylic acids are toxic because they indiscriminately complex and remove biologically important metals, especially zinc (23, 24, 25, 26). Thus there is a need to develop new and powerful chelating agents highly specific for tetravalent actinides, particularly Pu(IV). 

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