Search The Medical Knowledge Base

Drug Details

OMNIPAQUE

• Generic Name
  Iohexol
• Presentation
  Solution for injection. OMNIPAQUE solutions are colourless.
• Description
  180 mg, bottles containing 388 mg iohexol per ml, equivalent to 180 mg iodine per ml. 240 mg, bottles containing 518 mg iohexol per ml, equivalent to 240 mg Iodine per ml. 300 mg, bottles containing 647 mg iohexol per ml, equivalent to 300 mg iodine per ml. 350 mg, bottles containing 755 mg iohexol per ml, equivalent to 350 mg iodine per ml.
• Indications
  OMNIPAQUE is an X-ray contrast medium for use in adults and children for cardioangiography, arteriography, urography, phlebography and CT-enhancement. Lumbar, thoracic, cervical myelography and computed tomography of the basal cisterns, following subarachnoid injection. It is also indicated for arthrography, endoscopic retrograde pancreatography (ERP), endoscopic retrograde cholangiopancreatography (ERCP), herniography, hysterosalpingography, sialography and studies of the gastrointestinal tract when the use of barium sulphate is unsatisfactory, undesirable or contraindicated.
• Adult Dosage
  

  The dosage varies depending on the type of examination, age, weight, cardiac output and general condition of the patient and the technique used. Usually the same iodine concentration and volume is used as with other iodinated X-ray contrast media in current use. Adequate hydration should be assured before and after administration as for other contrast media.

  The following dosages may serve as a guide.

  Guidelines for Intravenous use

  Indication	Concentration	Volume	Comments
  Urography
  adults:	300 mg I/ml or 350 mg I/ml	40 - 80 ml 40 - 80 ml	80 ml may be exceeded in selected cases
  children < 7 kg	240 mg I/ml or 300 mg I/ml	4 ml/kg 3 ml/kg
  children > 7 kg	240 mg I/ml or 300 mg I/ml	3 ml/kg 2 ml/kg (max 40 ml)
  Phlebography (leg)	240 mg I/ml or 300 mg I/ml	20 - 100 ml/leg
  Digital subtraction angiography	300 mg I/ml or 350 mg I/ml	20 - 60 ml/inj. 20 - 60 ml/inj.
  CT-enhancement
  adults:	140 mg I/ml or 240 mg I/ml or 300 mg I/ml or 350 mg I/ml	100 - 400 ml 100 - 250 ml 100 - 200 ml 100 - 150 ml	Total amount of iodine is usually 30 - 60g
  Children:	240 mgI/ml	2-3 ml/kg b.w. up to 40ml	In a few cases up to 100 ml may be given
  	or 300 mgI/ml	1-3 ml/kg b.w. up to 40ml

• Elderly Dosage
  As for other adults.
• Contra Indications
  

  Manifest thyrotoxicosis. History of serious reaction to OMNIPAQUE.

• Special Precautions
  

  Special precautions for use of non-ionic monomeric contrast media in general:

  A positive history of allergy, asthma, or untoward reactions to iodinated contrast media indicates a need for special caution. Premedication with corticosteroids or histamine H₁ and H₂ antagonists might be considered in these cases.

  The risk of serious reactions in connection with use of OMNIPAQUE is regarded as minor. However, iodinated contrast media may provoke anaphylactoid reactions or other manifestations of hypersensitivity. A course of action should therefore be planned in advance, with necessary drugs and equipment available for immediate treatment, should a serious reaction occur. It is advisable always to use an indwelling cannula or catheter for quick intravenous access throughout the entire X-ray procedure.

  Non-ionic contrast media have less effect on the coagulation system in vitro, compared to ionic contrast media. When performing vascular catheterisation procedures one should pay meticulous attention to the angiographic technique and flush the catheter frequently (e.g.: with heparinised saline) so as to minimise the risk of procedure-related thrombosis and embolism.

  Adequate hydration should be assured before and after contrast media administration. This applies especially to patients with multiple myeloma, diabetes mellitus, renal dysfunction, as well as to infants, small children and elderly patients. Young infants (age < 1 year) and especially neonates are susceptible to electrolyte disturbance and haemodynamic alterations.

  Care should also be taken in patients with serious cardiac disease and pulmonary hypertension as they may develop haemodynamic changes or arrhythmias.

  Patients with acute cerebral pathology, tumours or a history of epilepsy are predisposed for seizures and merit particular care. Also alcoholics and drug addicts have an increased risk for seizures and neurological reactions. A few patients have experienced a temporary hearing loss or even deafness after myelography, which is believed to be due to a drop in spinal fluid pressure by the lumbar puncture per se.

  To prevent acute renal failure following contrast media administration, special care should be exercised in patients with pre-existing renal impairment and diabetes mellitus as they are at risk.

  Patients with paraproteinemias (myelomatosis and Waldenström's macroglobulinemia) are also at risk.

  Preventive measures include:

  • Identification of high risk patients
  • Ensuring adequate hydration. If necessary by maintaining an i.v. infusion from before the procedure until the contrast medium has been cleared by the kidneys.
  • Avoiding additional strain on the kidneys in the form of nephrotoxic drugs, oral cholecystographic agents, arterial clamping, renal arterial angioplasty, or major surgery, until the contrast medium has been cleared.
  • Postponing a repeat contrast medium examination until renal function returns to pre-examination levels.

  To prevent lactic acidosis, serum creatinine level should be measured in diabetic patients treated with metformin prior to intravascular administration of iodinated contrast medium.

  Normal serum creatinine / renal function: Administration of metformin should be stopped at the time of administration of contrast medium and not resumed for 48 hours or until renal function / serum creatinine is normal.

  Abnormal serum creatinine / renal function: Metformin should be stopped and the contrast medium examination delayed for 48 hours. Metformin should only be restarted if renal function / serum creatinine is unchanged.

  In emergency cases where renal function is abnormal or unknown, the physician should evaluate the risk / benefit of the contrast medium examination, and precautions should be implemented: Metformin should be stopped, patient hydrated, renal function monitored and patient observed for symptoms of lactic acidosis.

  A potential risk of transient hepatic dysfunction exists. Particular care is required in patients with severe disturbance of both renal and hepatic function, as they may have significantly delayed contrast medium clearance. Patients on haemodialysis may receive contrast media for radiological procedures. Correlation of the time of contrast media injection with the haemodialysis session is unnecessary.

  The administration of iodinated contrast media may aggravate the symptoms of myasthenia gravis. In patients with phaeochromocytoma undergoing interventional procedures, alpha blockers should be given as prophylaxis to avoid a hypertensive crisis. Special care should be exercised in patients with hyperthyroidism. Patients with multinodular goitre may be at risk of developing hyperthyroidism following injection of iodinated contrast media. One should also be aware of the possibility of inducing transient hypothyroidism in premature infants receiving contrast media.

  Extravasation of contrast media may on rare occasions give rise to local pain, and oedema, which usually recedes without sequelae. However, inflammation and even tissue necrosis have been seen. Elevating and cooling the affected site is recommended as routine measures. Surgical decompression may be necessary in cases of compartment syndrome.

  Observation-time:

  After contrast medium administration the patient should be observed for at least 30 minutes, since the majority of serious side effects occurs within this time. However, delayed reactions may occur.

• Interactions
  

  Use of contrast media may result in a transient impairment of renal function and this may precipitate lactic acidosis in diabetics who are taking metformin (see Warnings and Precautions).

  Patients treated with interleukin-2 less than two weeks previously have been associated with an increased risk for delayed reactions (flu-like symptoms or skin reactions).

  All iodinated contrast media may interfere with tests on thyroid function, thus the iodine binding capacity of the thyroid may be reduced for up to several weeks.

  High concentrations of contrast media in serum and urine can interfere with laboratory tests for bilirubin, proteins or inorganic substances (e.g. iron, copper, calcium and phosphate). These substances should therefore not be assayed on the day of examination.

• Adverse Drug Reactions
  

  General (applies to all uses of iodinated contrast media):

  Below are listed possible general side effects in relation with radiographic procedures, which include the use of non-ionic monomeric contrast media. For side effects specific to mode of administration, please refer to these specific sections.

  Undesirable effects associated with the use of iodinated contrast media are usually mild to moderate and transient in nature, and less frequent with non-ionic than with ionic contrast media. Serious reactions as well as fatalities are only seen on very rare occasions.

  The most frequent adverse event is a mild, general sensation such as a feeling of warmth or a transient metallic taste.

  Abdominal discomfort/pain and gastrointestinal reactions like nausea, vomiting and diarrhoea may occur.

  Hypersensitivity reactions are rare and usually present as mild respiratory or cutaneous symptoms like dyspnoe, rash, erythema, urticaria, pruritus and angioedema. They may appear either immediately after the injection or up to a few days later. Severe manifestations such as laryngeal oedema, bronchospasm or pulmonary oedema are very rare. Severe and even toxic skin reactions have been reported.

  Anaphylactoid reactions may occur irrespectively of the dose and mode of administration and mild symptoms of hypersensitivity may represent the first signs of a serious reaction. Administration of the contrast medium must be discontinued immediately and, if necessary, specific therapy instituted via the vascular access. Patients using beta-blockers may present with atypical symptoms of anaphylaxis, which may be misinterpreted as a vagal reaction.

  Vagal reactions giving hypotension and bradycardia are seen on very rare occasions.

  Headache or fever may occur. Episodes of hypertension may also occur. Pyrexia with rigors is seen on rare occasions.

  Iodism or "iodide mumps" is a very rare complication of iodinated contrast media resulting in swelling and tenderness of the salivary glands for up to approximately 10 days after the examination.