PENTETATE ZINC TRISODIUM
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PENTETATE ZINC TRISODIUM (PENTETATE ZINC TRISODIUM).
Pentetic acid (diethylenetriaminepentaacetic acid, DTPA) forms stable chelates with metal ions, particularly radioactive transuranic elements such as plutonium, americium, and curium. The zinc trisodium salt exchanges zinc for the radioactive metal, forming a stable, soluble complex that is rapidly excreted via the kidneys, thereby reducing radiation exposure.
| Metabolism | Pentetic acid is not significantly metabolized; it is excreted unchanged in the urine via glomerular filtration and active tubular secretion. |
| Excretion | Primarily renal elimination of the chelated complex (e.g., Zn-DTPA). In adults, >95% of the administered dose is excreted unchanged in urine within 24 hours, with minor biliary/fecal excretion (<5%). |
| Half-life | The terminal elimination half-life is approximately 1.5 to 2 hours for the Zn-DTPA complex in patients with normal renal function. In the setting of acute radiation exposure, this rapid clearance allows for early chelation. |
| Protein binding | Negligible protein binding (<5%) for the Zn-DTPA complex; it remains largely free in plasma. |
| Volume of Distribution | Approximately 0.2-0.3 L/kg, reflecting distribution primarily in extracellular fluid, with limited intracellular penetration. |
| Bioavailability | Intravenous: 100%. Intramuscular: Not recommended. Inhalation (nebulized): Approximately 20-30% systemic bioavailability, with local pulmonary action. Oral: <5% due to poor absorption and chelation in the gut. |
| Onset of Action | Intravenous administration: Clinical effect (enhanced elimination of radionuclides) begins immediately as chelation occurs in the bloodstream; measurable reduction in body burden within minutes. Inhalation (nebulized): Onset of pulmonary chelation is within 15-30 minutes. |
| Duration of Action | Single intravenous dose provides enhanced elimination for approximately 6-8 hours, after which repeat dosing is typically required. The duration is limited by rapid renal clearance. Continuous infusion may extend effect. |
1 g intravenous infusion over 1-2 hours once daily for up to 5 days.
| Dosage form | SOLUTION |
| Renal impairment | Contraindicated in patients with severe renal impairment (eGFR <30 mL/min/1.73 m²) or acute renal failure. No dose adjustment required for mild to moderate impairment. |
| Liver impairment | No specific dose adjustment recommended based on Child-Pugh class; use caution in severe hepatic impairment. |
| Pediatric use | Safety and efficacy not established; no standard dosing available. |
| Geriatric use | No specific geriatric dose adjustment; use with caution due to age-related renal function decline. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PENTETATE ZINC TRISODIUM (PENTETATE ZINC TRISODIUM).
| Breastfeeding | Not known if excreted in human milk. Preclinical data show Zn-DTPA distributes into rat milk. M/P ratio: not established. Due to potential for essential metal chelation in the infant, breastfeeding is not recommended during therapy or for 2 weeks after last dose. |
| Teratogenic Risk | FDA Pregnancy Category C. In animal studies, zinc trisodium diethylenetriaminepentaacetate (Zn-DTPA) was not teratogenic at doses up to 30 mg/kg/day in rats and rabbits. However, no adequate human studies exist. Ca- or Zn-DTPA can chelate essential trace metals (e.g., zinc, manganese) potentially causing fetal deficiency; effects may vary by trimester. First trimester: theoretical risk of metal depletion affecting organogenesis. Second/third trimester: risk of fetal growth restriction or anemia from zinc deficiency. Use only if potential benefit justifies risk. |
■ FDA Black Box Warning
None
| Serious Effects |
Known hypersensitivity to pentetic acid, zinc, or any component of the formulation.
| Precautions | May cause nephrotoxicity, especially in patients with pre-existing renal impairment; monitor renal function. May deplete essential metals (e.g., zinc, magnesium) with prolonged use; monitor and supplement as needed. Use caution in patients with asthma or allergic history; hypersensitivity reactions possible. Not for intravenous administration in patients with known hypersensitivity to any component. Safety and efficacy in children and pregnant women have not been established. |
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| Fetal Monitoring | Monitor maternal serum zinc, copper, and manganese levels weekly. Fetal monitoring: serial ultrasound for growth and amniotic fluid volume. Assess fetal iron status via maternal ferritin. Cardiotocography for fetal well-being if indicated. |
| Fertility Effects | Animal studies: Zn-DTPA at 30 mg/kg/day reduced fertility indices in rats (prolonged estrous cycles, fewer implants). In humans, data are lacking. Potential reversible impairment of spermatogenesis and oogenesis due to trace metal chelation. Advise pregnancy avoidance during therapy. |