Contrast media:
- Radiocontrast agents are per definition of drugs, but lack therapeutic effects. Contrast medium is used to enhance the visibility of internal structures in X-ray-based imaging techniques such as fluoroscopy.
- Modern intravenous contrast agents are typically based on iodine. This may be bound either in an organic (non-ionic) compound or an ionic compound.
Iodine-based contrast media are usually classified as:
- Ionic contrast media typically, but not always, have higher osmolality and more side-effects.
- Non-ionic contrast media have lower osmolality and tend to have fewer side-effects.