A Comprehensive Monograph on Iohexol

Executive Summary

Iohexol is a second-generation, non-ionic, low-osmolality, water-soluble iodinated radiographic contrast agent that stands as a cornerstone of modern diagnostic imaging. Marketed under brand names such as Omnipaque and Oraltag, its development represented a significant advancement in patient safety compared to older, first-generation high-osmolality ionic agents. Its chemical structure, featuring a tri-iodinated benzene ring with hydrophilic, non-ionizing side chains, allows for high concentrations of iodine necessary for X-ray attenuation while maintaining an osmolality closer to that of physiological fluids, thereby reducing systemic toxicity and improving patient tolerance.[1]

The clinical utility of Iohexol is exceptionally broad, encompassing a vast array of procedures across nearly all medical specialties. Its primary applications involve enhancing visualization during X-ray and Computed Tomography (CT) examinations. It is administered via multiple routes—intravascularly, intrathecally, orally, rectally, and into body cavities—to opacify vascular structures, the central nervous system (brain and spinal cord), the urinary tract, joints, and the gastrointestinal (GI) tract.[1] This versatility has secured its place on the World Health Organization's List of Essential Medicines.[1]