Iothalamic acid is a Radiographic Contrast Agent. The mechanism of action of iothalamic acid is as a X-Ray Contrast Activity. GLOFIL-125 (Sodium Iothalamate I-125 Injection) is a sterile, nonpyrogenic aqueous injection containing approximately 1 mg sodium iothalamate per mL, and 0.9 percent benzyl alcohol as a preservative. The radioactive concentration of the material is 250-300 µCi/mL as of the calibration date. Sodium bicarbonate and hydrochloric acid are present for pH adjustment. GLOFIL-125 (Sodium Iothalamate I-125 Injection) is indicated for evaluation of glomerular filtration in the diagnosis or monitoring of patients with renal disease. The renal clearance of sodium iothalamate in man closely approximates that of inulin. The compound is cleared by glomerular filtration without tubular secretion or reabsorption. Following infusion administration of I-125 iothalamate, the effective half-life is about 0.07 days.