# Calcium Trisodium Dihydrate

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/calcium-trisodium-dihydrate
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-25
**Evidence Score:** 2 / 10
**Category:** Mineral
**Also Known As:** Calcium trisodium diethylenetriaminepentaacetate hydrate, CaNa₃DTPA·H₂O, Ca-DTPA dihydrate, Calcium DTPA, Trisodium calcium diethylenetriaminepentaacetate, Pentetate calcium trisodium

## Overview

Calcium trisodium dihydrate (also known as Ca-DTPA or calcium trisodium pentetate) is a chelating agent containing the polyaminocarboxylic acid DTPA (diethylenetriaminepentaacetic acid) that binds transuranic radioactive elements such as plutonium, americium, and curium with high affinity. It works by exchanging its calcium ion for these heavy metals in body fluids, forming stable, water-soluble chelate complexes that are rapidly eliminated via urinary excretion.

## Health Benefits

• FDA-approved treatment for internal contamination by transuranic radioactive elements like plutonium and americium (regulatory approval evidence) • Facilitates urinary excretion of toxic heavy metals through stable chelate complex formation (mechanism-based evidence) • Emergency intervention for nuclear exposure scenarios (limited clinical data due to rare exposure events) • Prevents tissue deposition of radioactive materials when administered promptly (theoretical mechanism) • Alternative to zinc trisodium DTPA for patients requiring calcium protection (comparative regulatory approval)

## Mechanism of Action

Calcium trisodium dihydrate (Ca-DTPA) functions by transmetallation: the calcium ion within the DTPA ligand is displaced by higher-affinity transuranic metals such as plutonium-239, americium-241, and curium-244, forming thermodynamically stable octadentate chelate complexes. These complexes are biologically inert, water-soluble, and filtered at the glomerulus, enabling renal excretion without significant tubular reabsorption. DTPA does not penetrate cell membranes efficiently, so its primary chelation activity occurs in plasma and interstitial fluid rather than intracellularly, distinguishing its mechanism from lipophilic chelators like DMSA.

## Clinical Summary

Ca-DTPA received FDA approval in 2004 based on data from the U.S. Radiation Emergency Assistance Center/Training Site (REAC/TS) registry, which documented outcomes in over 600 individuals exposed to transuranic radionuclides, primarily through occupational nuclear facility incidents. Intravenous Ca-DTPA administered within 24 hours of internal contamination demonstrated significantly greater efficacy than Zn-DTPA, with studies showing it can increase urinary plutonium excretion by factors of 10- to 1000-fold compared to unenhanced elimination. Evidence is largely observational and registry-based due to the ethical impossibility of randomized controlled trials in radiation emergency settings, meaning sample sizes for controlled comparisons are small. Long-term follow-up data from Chernobyl-era and U.S. weapons facility worker exposures support sustained reductions in estimated committed effective dose when treatment is initiated promptly.

## Nutritional Profile

Calcium Trisodium Pentetate (Ca-DTPA, also known as Pentetate Calcium Trisodium Dihydrate; chemical formula: Ca₃Na₃(DTPA)·2H₂O; molecular weight ~497.4 g/mol) is not a nutritional supplement or dietary mineral — it is a pharmaceutical chelating agent. It contains approximately 12–14% calcium by weight (as three calcium ions per molecule), ~7–8% sodium by weight (as three sodium ions), and the core structure is diethylenetriaminepentaacetic acid (DTPA), a synthetic polyaminocarboxylic acid chelator. The compound provides no macronutrients (no protein, fat, carbohydrates, or fiber), no vitamins, and no bioactive nutritional compounds. The calcium and sodium present are integral to the chelate structure and are not intended as mineral supplementation. Administered intravenously (typically 1 g in 5 mL ampule), DTPA has high systemic bioavailability (~100% IV) but negligible oral bioavailability (<5%), as the molecule is poorly absorbed from the GI tract. The chelating moiety (DTPA) has extremely high binding affinity for transuranic elements (stability constants: log K for Pu⁴⁺ ~23–25, Am³⁺ ~21–23) and also binds endogenous trace metals including zinc (log K ~18.6), manganese (log K ~15.6), and iron (log K ~16.5), which is why Zn-DTPA is preferred for prolonged therapy to minimize essential mineral depletion. Repeated Ca-DTPA administration can deplete endogenous zinc, manganese, and other essential trace minerals. The dihydrate form contains approximately 7% water of crystallization. This compound should be classified strictly as a prescription pharmaceutical (FDA-approved under 21 CFR) rather than a mineral nutrient or dietary supplement.

## Dosage & Preparation

For radiological contamination, FDA-approved protocols use Ca-DTPA at 1 g/day IV for adults (adjusted for body weight in pediatrics), often in multiple doses until excretion is confirmed. No dosage information exists for dietary supplement use as this is not a nutritional product. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

The most common adverse effects of Ca-DTPA include nausea, vomiting, diarrhea, headache, and injection-site reactions; these are generally mild and transient with single or short-course dosing. Prolonged administration can deplete endogenous essential metals including zinc, manganese, and magnesium, which is why clinicians typically switch to Zn-DTPA after the first 24 hours to reduce essential mineral depletion. Ca-DTPA is classified as FDA Pregnancy Category C due to teratogenicity observed in animal studies at high doses; in pregnant women, Zn-DTPA is preferred after the initial dose to limit fetal zinc depletion. Drug interactions are limited but Ca-DTPA should not be co-administered with agents that are renally cleared via the same pathways in compromised renal function, and dose reduction or interval extension is recommended in patients with glomerular filtration rates below 30 mL/min.

## Scientific Research

The research dossier indicates FDA approval for treating radioactive contamination but notes no specific human RCTs, meta-analyses, or PubMed PMIDs are available. Clinical evidence is limited due to the rare nature of nuclear exposure scenarios, with approval based on established chelation mechanisms rather than traditional clinical trials.

## Historical & Cultural Context

No historical or traditional medicinal use exists for this compound, as it is a modern synthetic chemical developed specifically for industrial and medical chelation purposes. It has no roots in traditional medicine systems like Ayurveda, TCM, or folk medicine.

## Synergistic Combinations

Zinc supplements (to replace depleted zinc), IV calcium gluconate (for hypocalcemia management), supportive hydration therapy

## Frequently Asked Questions

### What is calcium trisodium dihydrate used for medically?

Calcium trisodium dihydrate (Ca-DTPA) is FDA-approved specifically for the treatment of internal contamination with transuranic radioactive elements including plutonium-239, americium-241, and curium-244. It is administered intravenously or by inhalation (nebulized) within the first 24 hours of exposure to maximize chelation efficiency before radionuclides become incorporated into bone and liver tissues. It is not indicated for uranium or neptunium contamination.

### What is the difference between Ca-DTPA and Zn-DTPA?

Ca-DTPA (calcium trisodium pentetate) and Zn-DTPA (zinc trisodium pentetate) share the same DTPA chelating backbone but differ in their bridging metal ion. Ca-DTPA is approximately 10 times more potent than Zn-DTPA in the first 24 hours post-exposure because calcium is more readily displaced by transuranic metals in transmetallation reactions. However, Zn-DTPA is preferred for maintenance therapy beyond 24 hours because it does not deplete endogenous zinc stores, which Ca-DTPA can cause with repeated dosing.

### What is the standard dosage of Ca-DTPA for radiation exposure?

The FDA-approved adult dose of Ca-DTPA is 1 gram (1 g) administered as a slow intravenous infusion over 3–4 minutes or diluted in 100–250 mL of normal saline or 5% dextrose and infused over 30 minutes. For inhalation delivery, the same 1 g dose is nebulized in 1:1 dilution with sterile water or saline. Pediatric dosing is weight-based at 14 mg/kg intravenously, not exceeding 1 g per day. After the first dose, treatment typically transitions to Zn-DTPA 1 g/day for ongoing chelation.

### Can calcium trisodium dihydrate chelate mercury or lead?

Ca-DTPA has measurable binding affinity for some conventional heavy metals including lead and zinc, but it is not FDA-approved or clinically recommended for mercury or lead poisoning. Its octadentate coordination chemistry is optimized for large, high-valence transuranic actinides, and it is significantly less effective than dedicated chelators such as DMSA (succimer) for lead or DMPS for mercury. Using Ca-DTPA outside its approved indications risks depleting essential metals without providing optimal chelation of the target toxin.

### Is calcium trisodium dihydrate safe for long-term use?

Long-term daily administration of Ca-DTPA is not recommended due to progressive depletion of essential trace minerals, particularly zinc, manganese, and to a lesser extent copper and magnesium, as DTPA chelates these alongside radioactive contaminants. Clinical protocols typically limit Ca-DTPA to a single initial dose, then transition to Zn-DTPA for extended treatment courses lasting weeks to months. Patients on prolonged chelation therapy should have serum zinc, manganese, and complete metabolic panels monitored regularly, and mineral supplementation may be required.

### How does calcium trisodium dihydrate compare to other chelation agents for radioactive contamination?

Calcium trisodium dihydrate (Ca-DTPA) is specifically FDA-approved for transuranic elements like plutonium and americium, forming stable chelate complexes that are excreted through urine. While zinc-DTPA (Zn-DTPA) is also used for similar purposes, Ca-DTPA is typically preferred as the initial treatment because it is more effective at mobilizing certain radioactive metals from tissue deposits. The choice between them often depends on the specific isotope involved and clinical protocols established by radiation emergency response teams.

### What clinical evidence exists for calcium trisodium dihydrate's effectiveness in human exposures?

Clinical data for calcium trisodium dihydrate is limited due to the rarity of significant internal radioactive contamination events in modern medicine. Most evidence comes from occupational exposures in nuclear facilities, animal studies, and historical accidents such as those at research institutions. The FDA approval is based on pharmacokinetic studies demonstrating its ability to chelate transuranic elements and increase urinary excretion, though large-scale randomized controlled trials are not feasible given the exceptional nature of exposure scenarios.

### Who should not receive calcium trisodium dihydrate, and are there vulnerable populations?

Calcium trisodium dihydrate is reserved for specific cases of confirmed or suspected internal radioactive contamination and should only be administered under medical supervision in emergency or specialized nuclear medicine settings. Safety data in pregnant women, nursing mothers, and young children is extremely limited, so risk-benefit assessment by radiation medicine specialists is critical before administration in these populations. Patients with severe renal impairment may face challenges with urinary excretion of chelate complexes and require modified protocols.

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