Introduction
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.
Uses
Iohexol is a contrast agent for intrathecal administration used in myelography and contrast enhancement for computerized tomography.
Iohexol ia used in myelography, arthrography, nephroangiography, arteriography, and other radiographic procedures.
Pharmacodynamics
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.
Absorption
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
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.
Half Life
Intrathecal half-life is 3.4 hours (mean). Intravascular is approximately 2 hours (with normal renal function).
Clearance
- 109 mL/min [Adult patients receiving 16-18 ml of iohexol (180 mgI/mL) by lumbar intrathecal injection]
Toxicity
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.
Food Interactions
No interactions found.
Dosage
Injection-
Angiocardiography:- Adult: Ventriculography: 350 mg iodine/ml: 30-60 ml, usual: 40 ml, may be repeated as necessary. If with selective coronary arteriography: max 250 ml. Selective coronary arteriography: 350 mg iodine/ml: 3-14 ml per inj, usual: 5 ml. Aortic root and arch study when used alone: 350 mg iodine/ml: 20-75 ml, usual 50 ml. Multiple procedures: 350 mg iodine/ml: max 250 ml.
- Child: Ventriculography: 350 mg iodine/ml: 1-1.5 ml/kg, usual: 1.25 ml/kg; 300 mg iodine/ml: 1.5-2 ml/kg, usual 1.75 ml/kg. Max: 5 ml/kg; 350 mg iodine/ml: 250 ml; 300 mg iodine/ml: 291 ml. Pulmonary angiography: 350 mg iodine/ml: 1 ml/kg. Multiple procedures: Max: 5 ml/kg; 350 mg iodine/ml: 250 ml; 300 mg iodine/ml: 291 ml.
- Adult: Use 300 or 350 mg iodine/ml solution, single inj. Aorta: 50-80 ml; major branches: 30-60 ml; renal arteries: 5-15 ml. Repeat as necessary. Max: 300 mg iodine/ml: 291 ml; 350 mg iodine/ml: 250 ml.
- Child: Use 350 mg iodine/ml solution: 1 ml/kg, single dose. Max: 5 ml/kg up to 250 ml.
- Adult: Use diluted solutions using sterile water for inj to concentrations of 50-100 mg iodine/ml. Usual volume: 50 mg iodine/ml solution: 50-600 ml; 100 mg iodine/ml: 50-300 ml.
- Child: Children: Use diluted solutions using sterile water for inj to concentrations of 50-100 mg iodine/ml: 50-300 ml.
- Adult: 240 mg iodine/ml: 15-20 ml; 300 mg iodine/ml: 15-20 ml.
- Adult: Knee: 240 mg iodine/ml: 5-15 ml; 300 mg iodine/ml: 5-15 ml; 350 mg iodine/ml: 5-10 ml. Shoulder: 240 mg iodine/ml: 3 ml; 300 mg iodine/ml: 10 ml. Temporomandibular: 300 mg iodine/ml: 0.5-1 ml. Lower volumes are recommended for double-contrast examinations; higher volumes are recommended fro single-contrast examinations.
- Adult: 240 mg iodine/ml: 50 ml.
- Adult: Use 300 or 350 mg iodine/ml solution: 200-350 mg iodine/kg.
- Child: Use 300 mg iodine/ml solution: 0.5-3 ml/kg, usual: 1-1.5 ml/kg; max: 3 ml/kg.
- Adult: Use 240 mg iodine/ml: 10-50 ml.
Intra-arterial-
Peripheral arteriography:- Adult: Aortofemoral runoffs: 350 mg iodine/ml: 20-70 ml; 300 mg iodine/ml: 30-90 ml. Selective arteriograms (femoral/iliac): 350 mg iodine/ml: 10-30 ml; 300 mg iodine/ml: 10-60 ml. Venography (per leg): 240 mg iodine/ml: 20-150 ml; 300 mg iodine/ml: 40-100 ml.
- Adult: Use 300 mg iodine/ml solution: Common carotid artery: 6-12 ml; internal carotid artery: 8-10 ml; external carotid artery: 6-9 ml; vertebral artery: 6-10 ml.
- Adult: Use 140 mg iodine/ml solution: Aorta: 20-45 ml at 8-20 ml/sec; carotid: 5-10 ml at 3-6 ml/sec; femoral: 9-20 ml at 3-6 ml/sec; vertebral: 4-10 ml at 2-8 ml/sec; renal: 6-12 ml at 3-6 ml/sec; other branches of the aorta (includes subclavian, axillary, innominate and iliac): 8-25 ml at 3-10 ml/sec.
Intrathecal-
Contrast-enhanced computerized tomography:- Adult: Lumbar (via lumbar inj): 180 mg iodine/ml: 10-17 ml; 240 mg iodine/ml: 7-12.5 ml. Thoracic (via lumbar or cervical inj): 240 mg iodine/ml: 6-12.5 ml; 300 mg iodine/ml: 6-10 ml. Cervical (via lumbar inj): 240 mg iodine/ml: 6-12.5 ml; 300 mg iodine/ml solution: 6-10 ml. Cervical (via C1-2 inj): 180 mg iodine/ml: 7-10 ml; 240 mg iodine/ml: 6-12.5 ml; 300 mg iodine/ml: 4-10 ml. Total columnar (via lumbar inj): 240 mg iodine/ml: 6-12.5 ml; 300 mg iodine/ml: 6-10 ml.
- Child: Use 180 mg iodine/ml solution. 0-<3 mth: 240 ml; 3-<36 mth: 4-8 ml; 3-<7 yr: 5-10 ml; 7-<13 yr: 5-12 ml; 13-18 yr: 6-15 ml.
Intravenous-
Contrast-enhanced computerized tomography of the abdomen:- Adult: In conjunction with dilute oral admin, use 300 mg iodine/ml solution: 100-150 ml. The oral dose is administered 20-40 min prior to IV dose and image acquisition.
- Child: In conjunction with dilute oral admin, use 240 or 300 mg iodine/ml solution: 1-2 ml/kg; max 3 ml/kg. The oral dose is administered 30-60 min prior to IV dose and image acquisition.
- Adult: 350 mg iodine/ml: 30-50 ml, as a bolus at 7.5-30 ml/second using a pressure injector, usually for 3 or more inj; max: 250 ml.
- Adult: Head imaging by inj: 300 mg iodine/ml: 70-150 ml; 350 mg iodine/ml: 80 ml. Head imaging by infusion: 240 mg iodine/ml: 120-250 ml. Body imaging by inj: 300 mg iodine/ml: 50-200 ml; 350 mg iodine/ml: 60-100 ml.
- Child: Head imaging: 240 or 300 mg iodine/ml: 1-2 ml/kg. Max: 28 g iodine with 240 mg iodine/ml solution or 35 g iodine with 300 mg iodine/ml solution.