Radio-labeled sodium iothalamate (Glofil-125) is a popular agent for the measurement of the glomerular filtration rate (GFR). The FDA-approved route of administration is by intravenous injection or continuous infusion. Israelit et al. [1], in 1973, first reported the subcutaneous route of administration. Subsequently, several investigators have validated the accuracy of this method of administration in the clinical setting [2–4]. As the pharmacist and pharmaceutical physician responsible for Glofil-125, we would like to offer the following comments from our experience in assisting with recent medical information inquiries about this product.