Last revised by Andrew Murphy on 23 Mar 2023

Iofendylate (generic names: ethyl 10-(4-iodophenyl)undecanoate or iodophenylundecylic acid) and sold under the tradename Myodil (except the USA where it was marketed as Pantopaque) was an oil-based contrast medium used for myelography

The iodine moiety of the compound causes high attenuation on radiography and CT 6. Its major drawback was its extremely slow resorption, with contrast medium persisting in situ for decades 6. Complete removal through aspiration was usually impossible after a procedure, and the remaining droplets could lead to chronic irritation and severe arachnoiditis.

In most patients, myelography was replaced by MRI of the spine, which did not require intrathecal contrast medium. In the rare cases in which MRI is contraindicated, and myelography (conventional/CT) is still required, iofendylate has been replaced by water-soluble iodinated contrast media 8

History and etymology

Iofendylate was introduced as a contrast medium in 1944, and when it was found to be less irritative to the meninges than Lipiodol it rapidly became the preferred contrast agent for myelograms (although some physicians, especially in the United States, continued to favor air). However iofendylate was officially discontinued in 1988 due to its risk of causing severe arachnoiditis 6,8.

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