EDETATE CALCIUM DISODIUM

EDETATE CALCIUM DISODIUM
(ed'e-tate)
Calcium Disodium Versenate
Classifications: chelating agent;
Therapeutic: chelating agent; antipoison agent
Pregnancy Category: B

Availability

200 mg/mL injection

Action

Chelating agent that combines with divalent and trivalent metals to form stable, nonionizing soluble complexes that can be readily excreted by kidneys. Action is dependent on ability of heavy metal to displace the less strongly bound calcium in the drug molecules.

Therapeutic Effect

Chelating agent that binds with heavy metals such as lead to form a soluble complex that can be excreted through the kidney, thereby ridding the body of the poisonous substance.

Uses

As adjunct in treatment of acute and chronic lead poisoning (plumbism). Generally used in combination with dimercaprol (BAL) in treatment of lead encephalopathy or when blood lead level exceeds 100 mcg/dL. Also used to diagnose suspected lead poisoning.

Unlabeled Uses

Treatment of poisoning from other heavy metals such as chromium, manganese, nickel, zinc, and possibly vanadium; removal of radioactive and nuclear fission products such as plutonium, yttrium, uranium. Not effective in poisoning from arsenic, gold, or mercury.

Contraindications

Severe kidney disease, active renal disease, anuria, oliguria; hepatitis; IV use in patients with lead encephalopathy not generally recommended (because of possible increase in intracranial pressure).

Cautious Use

Kidney dysfunction; active tubercular lesions; history of gout; pregnancy (category C); lactation.

Route & Dosage

Diagnosis of Lead Poisoning
Adult: IV/IM 500 mg/m² (max: 1 g) over 1 h, then collect urine for 24 h (if mcg lead:mg EDTA ratio in urine is >1, the test is positive)
Child: IM 50 mg/kg (max: 1 g), then collect urine for 6–8 h, (if mcg lead:mg EDTA ratio in urine is >0.5, the test is positive)

Treatment of Lead Poisoning
Adult/Child: IV 1–1.5 g/m²/d infused over 8–24 h for up to 5 d IM 1–1.5 g/m²/d divided q8–12h

Asymptomatic Lead Poisoning
Adult/Child: IV 1 g/m²/d infused over 8–24 h for up to 5 d

Lead Nephropathy/Renal Impairment
Adult: IV Based on serum creatinine <2 mg/dL, 1 g/m²/d x 5 d; 2–3 mg/dL, 500 mg/m²/d x 5 d; 3.1–4 x 3 doses mg/dL, 500 mg/m² q48h; >4 mg/dL, 500 mg/m² once/wk. Infuse over 8–24 h, may repeat monthly.

Administration

Note: Calcium disodium edetate can produce potentially fatal effects when higher than recommended doses are used or when it is continued after toxic effects appear.

Intramuscular

IM route preferred for symptomatic children and recommended for patients with incipient or overt lead-induced encephalopathy.
Add Procaine HCl to minimize pain at injection site (usually 1 mL of procaine 1% to each 1 mL of concentrated drug). Consult physician.
Use separate injection sites when dimercaprol (BAL) and Calcium EDTA are given concurrently.

Intravenous

PREPARE: IV Infusion: Dilute the 5 mL ampule with 250–500 mL of NS or D5W.

ADMINISTER: IV Infusion: Warning: Rapid IV infusion may be LETHAL by suddenly increasing intracranial pressure in patients who already have cerebral edema. Manufacturer recommends total daily dose over 8–12 h. Some clinicians recommend infusing over 1–2 h. Consult physician for specific rate.

INCOMPATIBILITIES Solution/additive: Amphotericin B, D10W hydralazine, Ringer's lactate.

Adverse Effects (≥1%)

CV: Hypotension, thrombophlebitis. GI: Anorexia, nausea, vomiting, diarrhea, abdominal cramps, cheilosis. Hematologic: Transient bone marrow depression, depletion of blood metals. Urogenital: Nephrotoxicity (renal tubular necrosis), proteinuria, hematuria. Body as a Whole: Febrile reaction (excessive thirst, fever, chills, severe myalgia, arthralgia, GI distress), histamine-like reactions (flushing, throbbing headache, sweating, sneezing, nasal congestion, lacrimation, postural hypotension, tachycardia).

Diagnostic Test Interference

Edetate calcium disodium may decrease serum cholesterol, plasma lipid levels (if elevated), and serum potassium values. Glycosuria may occur with toxic doses.

Interactions

Drug: May affect insulin requirements.

Pharmacokinetics

Absorption: Well absorbed IM. Onset: 1 h. Peak: Peak chelation 24–48 h. Distribution: Distributed to extracellular fluid; does not enter CSF. Metabolism: Not metabolized. Elimination: Chelated lead excreted in urine; 50% excreted in 1 h. Half-Life: 20–60 min IV, 90 min IM.

Nursing Implications

Assessment & Drug Effects

Determine adequacy of urinary output prior to therapy. This may be done by administering IV fluids before giving first dose.
Increase fluid intake to enhance urinary excretion of chelates. Avoid excess fluid intake, however, in patients with lead encephalopathy because of the danger of further increasing intracranial pressure. Consult physician regarding allowable intake.
Monitor I&O. Since drug is excreted almost exclusively via kidneys, toxicity may develop if output is inadequate. Stop therapy if urine flow is markedly diminished or absent. Report any change in output or I&O ratio to physician.
Lab tests: Obtain serum creatinine, calcium, and phosphorus before and during each course of therapy. Monitor baseline and frequent BUN levels and ECG during therapy. With prolonged therapy determine periodic determinations of blood trace element metals (e.g., copper, zinc, magnesium).
Be alert for occurrence of febrile reaction that may appear 4–8 h after drug infusion (see ADVERSE EFFECTS).

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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