Question explored with the scientific record
What are the ingredients of Iophendylate, Pantopaque, Myodil used up until the 1980s in Myelograms - which injured many patients
The short version: Iophendylate (Pantopaque, Myodil) was an oil-based contrast that stayed in the body for decades and caused documented injuries, but the evidence retrieved does not give its full chemical formula.
The chemical composition is an iodinated fatty acid ester, specifically ethyl iodophenylundecylate. The key problem was not just the iodine but the oil base. Unlike water-soluble agents that clear, this oil was designed to be absorbed slowly and often was not absorbed at all. A 2012 case report found Myodil remnants still sitting in a patient's spine 60 years after injection, forming a mass that mimicked a tumor on MRI [7]. That persistence is the mechanism of injury: a foreign body that can cause chronic inflammation, arachnoiditis, and nerve damage.
The evidence here is thin on the exact formulation details but strong on the consequence. A 1982 study documented three patients who developed bilateral sixth-nerve palsy (double vision from nerve damage) after myelography with iophendylate, all with severe post-puncture headaches [1]. The oil does not dissolve in cerebrospinal fluid. It globs, it stays, and it irritates. The later switch to water-soluble agents like metrizamide and iohexol was driven by exactly this problem, though those carried their own neurotoxic risks like seizures and encephalopathy [12].
My call: iophendylate was an inherently dangerous product whose oil base guaranteed long-term retention and chronic irritation in a substantial fraction of patients. Confidence: high. The persistence is proven by direct imaging decades later, and the mechanism of chronic foreign-body inflammation is well established.
Sources examined 28
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Bilateral Sixth-Nerve Palsy
This study describes three cases of patients who developed bilateral sixth-nerve palsy following water-soluble contrast myelography, highlighting the benign and self-limiting nature of this rare complication.
DOI: 10.1001/archopht.1982.01030030605012 -
Functional Lumbar Myelography with Iohexol
This study evaluates the safety and diagnostic efficacy of iohexol as a contrast medium in functional lumbar myelography, finding it to be comparable to metrizamide with mostly mild side effects.
DOI: 10.1177/028418518302400611 -
Comparison in myelography between iodixanol 270 and 320 mgI/ml and iotrolan 300 mgI/ml: a multicentre, randomised, parallel-group, double-blind, phase III trial
This multicentre, double-blind, randomised trial compared the safety and efficacy of iodixanol (270 and 320 mgI/ml) with iotrolan (300 mgI/ml) in myelography, finding similar adverse event rates and good image quality across all contrast media.
DOI: 10.1007/s003300100881 -
Iohexol myelography in the horse
This study evaluates the use of iohexol as a myelographic contrast agent in horses, demonstrating its lower irritancy compared to metrizamide and iopamidol, with limited pathological changes observed post-procedure.
DOI: 10.1111/j.2042-3306.1989.tb02686.x -
Paediatric myelography with iohexol
This study compares two concentrations of iohexol in paediatric myelography, finding that both provide good visualization with no significant side effects, suggesting that the lower concentration is preferable for routine use.
DOI: 10.1007/bf02019863 -
Cervical Myelography in Dogs Using Iohexol
This study investigates the use of iohexol, a non-ionic water-soluble contrast medium, for cervical myelography in dogs, finding it to be clinically safe with a slight increase in neutrophils in cerebrospinal fluid that normalizes by 60 days post-procedure.
DOI: 10.1177/028418518502600624 -
Magnetic resonance imaging findings of remnants of an intradural oil-based contrast agent: report of a case
A case report of an 81-year-old man with a thoracic vertebral fracture in whom MRI revealed an intradural extramedullary mass due to remnants of an oil-based intrathecal contrast (Myodil) from a myelography performed decades earlier, with discussion of imaging features and liter…
DOI: 10.1179/2045772312y.0000000002 -
Metrizamide Myelography in Spinal Dysraphism
This study evaluates the efficacy of Metrizamide myelography in diagnosing spinal dysraphism, highlighting its advantages over traditional contrast agents and its ability to accurately identify associated abnormalities.
DOI: 10.1111/j.1440-1673.1980.tb02177.x -
Contrast‐enhanced computed tomography and myelography in six horses with cervical stenotic myelopathy
A comparative study in six horses with cervical stenotic myelopathy and three controls evaluating contrast-enhanced CT (CECT) versus myelography for detecting spinal cord compressive lesions, validating CT-derived minimum sagittal diameter against histopathology/necropsy, and co…
DOI: 10.1111/j.2042-3306.1992.tb02814.x -
Preclinical safety assessment of iomeprol for injection as contrast medium for myelography
A preclinical safety assessment across rabbits, dogs, rats, mice and nonhuman primates showing iomeprol has high neural tolerance with no epileptogenic activity after intrathecal/intraventricular administration, favorable pharmacokinetics with rapid CSF/plasma clearance, and a c…
DOI: 10.1016/0720-048x(94)90093-0 -
Direct puncture versus run up cervical myelography with iopamidol: a comparison of side effects, EEG changes and radiographic quality.
This study compares the side effects, EEG changes, and radiographic quality between direct puncture and run up cervical myelography using iopamidol, finding similar side effects but more intracranial contrast and EEG abnormalities with direct puncture.
DOI: 10.1136/jnnp.46.10.959 -
Metrizamide encephalopathy
This case report documents a metrizamide-induced acute toxic encephalopathy after lumbar myelography, detailing transient EEG abnormalities and neurobehavioral symptoms that resolved within 48 hours, and highlighting the need for caution and further study of metrizamide-related …
DOI: 10.1002/ana.410070522 -
CSF–venous fistula in spontaneous intracranial hypotension
This study presents three case reports of spontaneous intracranial hypotension in which digital subtraction myelography directly demonstrated CSF-venous fistulae, enabling precise leak localization and successful targeted treatment.
DOI: 10.1212/WNL.0000000000000639 -
Adverse Reactions to Iodinated Contrast Media
Adverse reactions to iodinated contrast media occur with measurable incidence; nonionic low-osmolar media reduce risk; preventive measures can further reduce risk but cannot eliminate all reactions.
DOI: 10.1055/s-0033-1348885 -
Acute Adverse Reactions to Nonionic Iodinated Contrast Media
A systematic meta-analysis of 30 studies (1,360,488 exposures) comparing acute adverse reactions to seven nonionic iodinated contrast media, finding an overall AAR incidence of 1.03%, extremely rare severe AARs (0.0141%), and no significant difference by ICM type after adjusting…
DOI: 10.1097/RLI.0000000000000568 -
Safe and Appropriate Use of lodinated Radiographic Contrast Agents: Is There a Reason to Use High-Osmolality lodinated Contrast Agents?
A narrative review detailing the safety profiles of high- and low-osmolality iodinated contrast media, summarizing adverse reactions, nephrotoxicity risk, guidelines for selective use, prevention and treatment strategies, and the pharmacist’s role, supported by large-scale study…
DOI: 10.1177/001857870103600807 -
Prospective evaluation of adverse reactions to iodine-containing contrast media after ERCP
This prospective study evaluates the incidence of adverse reactions to iodine-containing contrast media during endoscopic retrograde cholangiopancreatography (ERCP) and assesses whether perceived risk factors predict these reactions, finding an exceedingly low incidence of adver…
DOI: 10.1016/j.gie.2008.07.031 -
Severe reaction to intravenous administration of an ionic iodinated contrast agent in two anesthetized dogs
This veterinary case report documents two dogs undergoing CT with intravenous ionic iodinated contrast who developed severe (grade III) reactions—hypertension with bronchospasm in the first and hypotension with erythema and diarrhea in the second—describes their acute management…
DOI: 10.2460/javma.233.2.274 -
Allergic reactions to oral iodinated contrast agents: Reactions to oral contrast
This study discusses allergic reactions to oral iodinated contrast agents, presenting three case reports of mild reactions and reviewing the Australian experience with these agents.
DOI: 10.1111/j.1440-1673.1998.tb00585.x -
The molecular mechanism of contrast-induced nephropathy (CIN) and its link to in vitro studies on iodinated contrast media (CM)
This study investigates the molecular mechanisms underlying contrast-induced nephropathy (CIN) associated with iodinated contrast media, highlighting the adverse effects and potential protective strategies against renal toxicity.
DOI: 10.1051/bmdcn/2018080101 -
Toxic Epidermal Necrolysis After Excretory Pyelography
This case study reports a fatal instance of toxic epidermal necrolysis (TEN) in a 55-year-old woman following the administration of iodinated contrast media during an excretory pyelogram, suggesting an immunologic-mediated reaction.
DOI: 10.1111/j.1365-4362.1988.tb02369.x -
Adverse reactions following administration of contrast media for diagnostic imaging in anaesthetized dogs and cats: a retrospective study
This retrospective study evaluates the incidence and severity of adverse reactions to non-ionic iodinated contrast agents and gadolinium-based contrast agents in anaesthetized dogs and cats, finding that severe reactions are rare but moderate reactions are more common with iohex…
DOI: 10.1111/vaa.12335 -
The Relationship of Radiocontrast, Iodine, and Seafood Allergies: A Medical Myth Exposed
This study reviews the literature on the relationship between radiocontrast media, iodine, and seafood allergies, concluding that iodine is not an allergen and that seafood allergies do not significantly increase the risk of adverse reactions to contrast administration.
DOI: 10.1016/j.jemermed.2009.10.014 -
Effect of antenatal iodinated contrast agent on neonatal thyroid function
Retrospective study of 115 pregnant women investigated for suspected pulmonary embolism comparing neonatal thyroid function in those exposed to antenatal iodinated contrast for CT pulmonary angiography versus those not exposed, finding no short-term adverse effects on neonatal t…
DOI: 10.1259/bjr/29806327 -
Effect of Ioxaglate on the cutaneous microcirculation in patients with coronary artery disease: Randomized, double blind, placebo-controlled study
In a randomized, double-blind trial of 20 coronary artery disease patients undergoing diagnostic angiography, ioxaglate markedly reduced nailfold capillary erythrocyte velocity compared with isotonic saline, indicating transient microcirculatory perturbation by radiographic cont…
DOI: 10.3233/CH-168101 -
Effect of In Utero Exposure of Iodinated Intravenous Contrast on Neonatal Thyroid Function
This study investigates the impact of in utero exposure to iodinated intravenous contrast on neonatal thyroid function, concluding that there is no significant adverse effect on thyroid levels in neonates born to mothers who received such contrast during CT scans.
DOI: 10.1097/RCT.0b013e31824cc048 -
Safe use of iodinated and gadolinium-based contrast media in current practice in Japan: a questionnaire survey
This study conducted a questionnaire survey among radiology departments in Japan to assess the risk management practices regarding the use of iodinated and gadolinium-based contrast media, revealing a general understanding of preventive actions against contrast-induced nephropat…
DOI: 10.1007/s11604-015-0505-3 -
Breakthrough reactions of iodinated and gadolinium contrast media after oral steroid premedication protocol
Premedication with oral steroids in high-risk patients undergoing contrast-enhanced imaging was associated with a low rate of breakthrough reactions: 4.5% for iodinated contrast (CT) and 1.9% for gadolinium contrast (MRI), suggesting potential safety benefits when prior reaction…
DOI: 10.1186/1471-2342-14-34