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sodium iothalamate (125I)

V09CX03

Forms & Strengths

Solution for injection: 37 MBq/mL (1 mCi/mL) of iodine-125

Adult Dosing

Glomerular filtration rate (GFR) determination: 1.85 to 3.7 MBq (50 to 100 microcuries) intravenously as a single injection
Effective renal plasma flow (ERPF): Continuous infusion methods utilized per specialized nuclear medicine protocols

Pediatric Dosing

Safety and effectiveness in pediatric patients have not been established
Dosage must be individualized based on body surface area or weight under specialized nuclear medicine protocols if used off-label

Indications

Measurement of glomerular filtration rate (GFR)
Evaluation of renal function via radioactive tracer clearance studies

Mechanism of Action

Iothalamate is filtered exclusively by the renal glomeruli without significant tubular secretion or reabsorption
Radioactive iodine-125 label emits gamma radiation allowing external detection and measurement of plasma and urine radioactivity to calculate GFR

Contraindications

Known hypersensitivity to iothalamate or iodine-containing compounds
Pregnancy and lactation due to fetal and neonatal exposure to ionizing radiation

Adverse Reactions

Rare hypersensitivity or anaphylactoid reactions including skin rash, urticaria, and pruritus
Injection site reactions such as mild pain or erythema

Drug Interactions

Drugs altering renal hemodynamics (e.g., NSAIDs, ACE inhibitors, diuretics) may falsely alter measured GFR clearance rates
Concurrent administration of other iodinated contrast agents or radiopharmaceuticals may interfere with counting equipment or baseline radioactivity measurements

Curated Content: Needs Vetting Before Put to Clinical Use