Glofil-125 is a sterile aqueous injection containing sodium iothalamate. Glofil-125 is used for evaluation of glomerular filtration in the monitoring or diagnosis of patients with renal disease. Glofil-125 is popular for the measurement of the glomerular filtration rate (GFR). Glofil-125 is a Radiopaque agent, which contains iodine and absorbs x-rays. Depending on how it is given, Glofil-125 builds up in a particular area of the patient's body. This leads to a high level of iodine in that area, which allows x-rays to take a clearer picture.