Iohexol is a contrast agent for intrathecal administration used in myelography and contrast enhancement for computerized tomography.

Brand Names
Omnipaque, Oraltag
Generic Name
DrugBank Accession Number

Iohexol is an effective non-ionic, water-soluble contrast agent which is used in myelography, arthrography, nephroangiography, arteriography, and other radiographic procedures. Its low systemic toxicity is the combined result of low chemotoxicity and low osmolality.

Small Molecule
Average: 821.1379
Monoisotopic: 820.880309705
Chemical Formula
  • Iohexol
  • Iohexolum
  • N,N'-Bis(2,3-dihydroxypropyl)-5-(N-(2,3-dihydroxypropyl)acetamido)-2,4,6-triiodoisophthalamide
External IDs
  • WIN 39424
  • WIN-39424



Iohexol ia used in myelography, arthrography, nephroangiography, arteriography, and other radiographic procedures.

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Iohexol is an effective non-ionic, water-soluble contrast agent which is used in myelography, arthrography, nephroangiography, arteriography, and other radiographic procedures. Its low systemic toxicity is the combined result of low chemotoxicity and low osmolality.

Mechanism of action

Organic iodine compounds block x-rays as they pass through the body, thereby allowing body structures containing iodine to be delineated in contrast to those structures that do not contain iodine. The degree of opacity produced by these compounds is directly proportional to the total amount (concentration and volume) of the iodinated contrast agent in the path of the x-rays. After intrathecal administration into the subarachnoid space, diffusion of iohexol in the CSF allows the visualization of the subarachnoid spaces of the head and spinal canal. After intravascular administration, iohexol makes opaque those vessels in its path of flow, allowing visualization of the internal structures until significant hemodilution occurs.


Small amounts are absorbed through the bladder via intravesical instillation. Following intrauterine instillation, the majority of the medium within the uterine cavity is discharged into the vagina immediately upon termination of procedure. However, any medium retained in the uterine or peritoneal cavity is absorbed systemically within 60 minutes. May not be absorbed for up to 24 hours if tubes are obstructed and dilated.

Volume of distribution
  • 350-849 mL/kg
Protein binding

Not Available

Not Available
Route of elimination

Iohexol is absorbed from cerebrospinal fluid (CSF) into the bloodstream and is eliminated by renal excretion. No significant metabolism, deiodination, or biotransformation occurs.


Intrathecal half-life is 3.4 hours (mean). Intravascular is approximately 2 hours (with normal renal function).

  • 109 mL/min [Adult patients receiving 16-18 ml of iohexol (180 mgI/mL) by lumbar intrathecal injection]
Adverse Effects
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Non-ionic radiocontrast agents like iohexol are cytotoxic to renal cells. The toxic effects include apoptosis, cellular energy failure, disruption of calcium homeostasis, and disturbance of tubular cell polarity, and are thought to be linked to oxidative stress.

Not Available
Pharmacogenomic Effects/ADRs
Not Available


Drug Interactions
This information should not be interpreted without the help of a healthcare provider. If you believe you are experiencing an interaction, contact a healthcare provider immediately. The absence of an interaction does not necessarily mean no interactions exist.
AcetazolamideThe therapeutic efficacy of Acetazolamide can be decreased when used in combination with Iohexol.
AldesleukinThe risk of a hypersensitivity reaction to Iohexol is increased when it is combined with Aldesleukin.
AmifampridineThe risk or severity of seizure can be increased when Iohexol is combined with Amifampridine.
AmobarbitalThe therapeutic efficacy of Amobarbital can be decreased when used in combination with Iohexol.
BrexanoloneThe therapeutic efficacy of Brexanolone can be decreased when used in combination with Iohexol.
BrivaracetamThe therapeutic efficacy of Brivaracetam can be decreased when used in combination with Iohexol.
BupropionThe risk or severity of seizure can be increased when Bupropion is combined with Iohexol.
ButalbitalThe therapeutic efficacy of Butalbital can be decreased when used in combination with Iohexol.
CannabidiolThe therapeutic efficacy of Cannabidiol can be decreased when used in combination with Iohexol.
CarbamazepineThe therapeutic efficacy of Carbamazepine can be decreased when used in combination with Iohexol.
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Food Interactions
No interactions found.


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International/Other Brands
Histodenz (Sigma) / Nycodenz
Brand Name Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing EndRegionImage
OmnipaqueSolution388.3 mg/1mLIntravenousApothecary Shop Wholesale Inc.2011-07-012011-08-31US flag
OmnipaqueInjection, solution240 mg/1mLIntra-articular; Intrathecal; Intravascular; Intravenous; Oral; RectalGE Healthcare Inc.1985-12-26Not applicableUS flag
OmnipaqueSolution647.1 mg/1mLIntravenousApothecary Shop Wholesale Inc.2011-07-012011-08-31US flag
OmnipaqueInjection, solution350 mg/1mLIntravascular; Intravenous; Oral; RectalGE Healthcare Inc.2004-09-03Not applicableUS flag
OmnipaqueSolution12 mg/1mLOralGE Healthcare Inc.2018-04-27Not applicableUS flag
OmnipaqueInjection, solution180 mg/1mLIntrathecal; Oral; RectalGE Healthcare Inc.2004-07-15Not applicableUS flag
OmnipaqueSolution518 mg/1mLIntravenousApothecary Shop Wholesale Inc.2011-06-012011-08-31US flag
OmnipaqueInjection, solution300 mg/1mLIntrathecal; Intravascular; Intravenous; Oral; RectalGE Healthcare Inc.2004-09-03Not applicableUS flag
OmnipaqueSolution9 mg/1mLOralGE Healthcare Inc.2018-04-27Not applicableUS flag
OmnipaqueInjection, solution140 mg/1mLIntravascular; IntravenousGE Healthcare Inc.2004-05-25Not applicableUS flag


ATC Codes
V08AB02 — Iohexol
Drug Categories
Chemical TaxonomyProvided by Classyfire
This compound belongs to the class of organic compounds known as o-haloacetanilides. These are organic compounds containing an acetamide group conjugated to a phenyl group, which is in turn ortho-substituted with a halogen atom.
Organic compounds
Super Class
Benzene and substituted derivatives
Sub Class
Direct Parent
Alternative Parents
P-haloacetanilides / Iodobenzenes / Aryl iodides / Tertiary carboxylic acid amides / Acetamides / Secondary alcohols / Propargyl-type 1,3-dipolar organic compounds / Carboximidic acids / Primary alcohols / Organopnictogen compounds
show 5 more
Acetamide / Alcohol / Aromatic homomonocyclic compound / Aryl halide / Aryl iodide / Carbonyl group / Carboxamide group / Carboximidic acid / Carboximidic acid derivative / Carboxylic acid derivative
show 18 more
Molecular Framework
Aromatic homomonocyclic compounds
External Descriptors
organoiodine compound, benzenedicarboxamide (CHEBI:31709)
Affected organisms
  • Humans and other mammals

Chemical Identifiers

CAS number
InChI Key


Synthesis Reference

Xiu C. Wang, Steve A. Chamberlin, Ashok V. Bhatia, Gregg E. Robinson, John Hufnagel, "Process for the preparation of iohexol." U.S. Patent US5705692, issued December, 1985.

General References
  1. Kawada TK: Iohexol and iopamidol: second-generation nonionic radiographic contrast media. Drug Intell Clin Pharm. 1985 Jul-Aug;19(7-8):525-9. [Article]
  2. Shaw DD, Potts DG: Toxicology of iohexol. Invest Radiol. 1985 Jan-Feb;20(1 Suppl):S10-3. [Article]
  3. FDA Approved Drug Products: OMNIPAQUE (iohexol) injection and oral solution. [Link]
Human Metabolome Database
PubChem Compound
PubChem Substance

Clinical Trials

Clinical Trials
4CompletedNot AvailableHuman Immunodeficiency Virus (HIV) Infections1
4CompletedDiagnosticContrast Media Dosing1
4CompletedDiagnosticHealthy Subjects (HS)1
4CompletedDiagnosticHormone Replacement Therapy / Renal Function / Transgender1
4CompletedTreatmentHuman Immunodeficiency Virus Type 1 (HIV-1) Infection1
4CompletedTreatmentRenal Cirrhosis1
4Not Yet RecruitingDiagnosticTranscatheter Aortic Valve Replacement (TAVR)1
4Not Yet RecruitingOtherLung Disorder1
4RecruitingBasic ScienceHeart Failure2
4RecruitingDiagnosticContrast media reaction / Coronary Artery Disease (CAD)1


Not Available
  • GE Healthcare Inc.
  • Hospira Inc.
  • Nycomed Inc.
Dosage Forms
Injection, solutionParenteral
InjectionIntra-arterial; Intrathecal; Intravenous647 mg/ml
Injection, solutionIntra-arterial; Intravenous755 mg/ml
Solution300 mg
Solution350 mg
SolutionIntra-arterial; Intrathecal; Intravenous300 mg/ml
SolutionIntra-arterial; Intrathecal; Intravenous350 mg/ml
Injection, solution
SolutionIntra-articular; Intrathecal; Intravenous647 mg
Injection, solutionIntravenous647 mg
SolutionIntra-arterial; Intrathecal; Intravenous300 mg
InjectionIntra-articular; Intrathecal; Intravascular; Intravenous; Oral; Rectal
InjectionIntra-articular; Intravascular; Intravenous; Oral
Injection, solutionIntra-articular; Intrathecal; Intravascular; Intravenous; Oral; Rectal240 mg/1mL
Injection, solutionIntrathecal; Intravascular; Intravenous; Oral; Rectal300 mg/1mL
Injection, solutionIntrathecal; Oral; Rectal180 mg/1mL
Injection, solutionIntravascular; Intravenous140 mg/1mL
Injection, solutionIntravascular; Intravenous; Oral; Rectal350 mg/1mL
Injection, solutionParenteral518 mg/ml
Injection, solutionParenteral647 mg/ml
Injection, solutionParenteral755 mg/ml
SolutionIntravenous388.3 mg/1mL
SolutionIntravenous518 mg/1mL
SolutionIntravenous647.1 mg/1mL
SolutionOral12 mg/1mL
SolutionOral9 mg/1mL
Solution350 mg/1ml
SolutionSubarachnoid388 mg / mL
LiquidSubarachnoid180 mg / mL
SolutionIntravascular; Subarachnoid518 mg / mL
LiquidIntravenous; Subarachnoid240 mg / mL
SolutionIntravascular; Subarachnoid647 mg / mL
LiquidIntravenous; Subarachnoid300 mg / mL
Injection, solutionIntrathecal647 mg
InjectionIntrathecal647 mg/ml
SolutionIntravascular755 mg / mL
LiquidIntravenous350 mg / mL
InjectionIntrathecal755 mg/ml
InjectionIntra-arterial; Intrathecal; Intravenous
InjectionIntra-arterial; Intracavitary; Intrathecal; Intravascular; Intravenous300 mg/ml
InjectionIntravascular350 mg/ml
SolutionIntra-arterial; Intra-articular; Intrathecal; Intrauterine; Intravenous; Oral; Rectal300 mg
SolutionIntra-arterial; Intravenous350 mg
Injection, solutionIntravenous755 mg/ml
Injection, solutionIntravenous
InjectionIntrathecal300 mg/mL
Injection, solutionIntravenous350 mg/mL
For solutionOral4.5 g/1
Injection, solution300 mg/1ml
Injection, solution350 mg/1ml
Solution300 mg/1ml
Unit descriptionCostUnit
Myelo-kit 180 mg/ml62.19USD each
Omnipaque 240 mg/ml vial5.34USD ml
Omnipaque 180 mg/ml vial4.92USD ml
Omnipaque 300 mg/ml vial4.82USD ml
Omnipaque 210 mg/ml vial3.53USD ml
Omnipaque 350 mg/ml cartridge2.29USD ml
Omnipaque 300 mg/ml cartridge2.17USD ml
Omnipaque 240 mg/ml cartridge1.77USD ml
Omnipaque 300 mg/ml syringe1.08USD ml
Omnipaque 350 mg/ml infu btl1.08USD ml
Omnipaque 140 mg/ml vial0.78USD ml
DrugBank does not sell nor buy drugs. Pricing information is supplied for informational purposes only.
Not Available


Experimental Properties
melting point (°C)174-180 °CPhysProp
logP-3.05HANSCH,C & LEO,AJ (1985)
Predicted Properties
Water Solubility0.796 mg/mLALOGPS
pKa (Strongest Acidic)11.73Chemaxon
pKa (Strongest Basic)-3Chemaxon
Physiological Charge0Chemaxon
Hydrogen Acceptor Count9Chemaxon
Hydrogen Donor Count8Chemaxon
Polar Surface Area199.89 Å2Chemaxon
Rotatable Bond Count12Chemaxon
Refractivity148.84 m3·mol-1Chemaxon
Polarizability60.37 Å3Chemaxon
Number of Rings1Chemaxon
Rule of FiveNoChemaxon
Ghose FilterNoChemaxon
Veber's RuleNoChemaxon
MDDR-like RuleNoChemaxon
Predicted ADMET Features
Human Intestinal Absorption-0.8406
Blood Brain Barrier-0.5082
Caco-2 permeable-0.6474
P-glycoprotein substrateSubstrate0.5
P-glycoprotein inhibitor INon-inhibitor0.8375
P-glycoprotein inhibitor IINon-inhibitor0.8629
Renal organic cation transporterNon-inhibitor0.9534
CYP450 2C9 substrateNon-substrate0.7747
CYP450 2D6 substrateNon-substrate0.8175
CYP450 3A4 substrateNon-substrate0.6895
CYP450 1A2 substrateNon-inhibitor0.919
CYP450 2C9 inhibitorNon-inhibitor0.9071
CYP450 2D6 inhibitorNon-inhibitor0.9303
CYP450 2C19 inhibitorNon-inhibitor0.9025
CYP450 3A4 inhibitorNon-inhibitor0.971
CYP450 inhibitory promiscuityLow CYP Inhibitory Promiscuity0.7514
Ames testNon AMES toxic0.9035
BiodegradationNot ready biodegradable0.9937
Rat acute toxicity1.6446 LD50, mol/kg Not applicable
hERG inhibition (predictor I)Weak inhibitor0.9895
hERG inhibition (predictor II)Non-inhibitor0.7193
ADMET data is predicted using admetSAR, a free tool for evaluating chemical ADMET properties. (23092397)


Mass Spec (NIST)
Not Available
SpectrumSpectrum TypeSplash Key
Predicted GC-MS Spectrum - GC-MSPredicted GC-MSNot Available
Predicted MS/MS Spectrum - 10V, Positive (Annotated)Predicted LC-MS/MSNot Available
Predicted MS/MS Spectrum - 20V, Positive (Annotated)Predicted LC-MS/MSNot Available
Predicted MS/MS Spectrum - 40V, Positive (Annotated)Predicted LC-MS/MSNot Available
Predicted MS/MS Spectrum - 10V, Negative (Annotated)Predicted LC-MS/MSNot Available
Predicted MS/MS Spectrum - 20V, Negative (Annotated)Predicted LC-MS/MSNot Available
Predicted MS/MS Spectrum - 40V, Negative (Annotated)Predicted LC-MS/MSNot Available
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-0udi-0000000090-ec4e884f5d1e3e37a84f
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-0udi-0020002090-d8ff0c2813768e3cf012
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-00dj-0009850000-7a1ca449a56d19c39ea8
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-0fk9-0009120000-a8c863a64d387cfd461a
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-0kmi-0496000000-bff588cc0e98918355e8
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-05fu-0492000000-4a9469f17183d2f9f291
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-0udi-0020003090-7423fd2df7e59f0f78ee
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-0fka-0008951000-ea0d52cf6d356a7f3590
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-0fk9-0029120000-e5ff4d33e064ff47ff49
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-0kmi-0395000000-775d49075e4ad66be119
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-05i1-0492000000-1a8b12a2e372f5b00ca1
LC-MS/MS Spectrum - LC-ESI-ITFT , positiveLC-MS/MSsplash10-0udi-0000000090-262fc3f19d8442742408

Drug created at July 06, 2007 19:54 / Updated at December 06, 2023 02:33