"It only takes one bad apple to spoil the bunch, and the same may be true of certain proteins in the brain. Studies have suggested that just one rogue protein (in this case, a protein that is misfolded or shaped the wrong way) can act as a seed"...
SEVERE ADVERSE EVENTS-INADVERTENT INTRATHECAL ADMINISTRATION: Serious adverse reactions have been reported due to the inadvertent intrathecal administration of iodinated contrast media that are not indicated for intrathecal use. These serious adverse reactions include: death, convulsions, cerebral hemorrhage, coma, paralysis, arachnoiditis, acute renal failure, cardiac arrest, seizures, rhabdomyolysis, hyperthermia, and brain edema. Special attention must be given to insure that this drug product is not administered intrathecally.
Nonionic iodinated contrast media inhibit blood coagulation, in vitro, less than ionic contrast media. Clotting has been reported when blood remains in contact with syringes containing nonionic contrast media. The use of plastic syringes in place of glass syringes has been reported to decrease but not eliminate the likelihood of in vitro clotting.
Serious, rarely fatal, thromboembolic events causing myocardial infarction and stroke have been reported during angiographic procedures with both ionic and nonionic contrast media. Therefore, meticulous intravascular administration technique is necessary, particularly during angiographic procedures, to minimize thromboembolic events. Numerous factors, including length of procedure, catheter and syringe material, underlying disease state, and concomitant medications may contribute to the development of thromboembolic events. For these reasons, meticulous angiographic techniques are recommended including close attention to guide wire and catheter manipulation, use of manifold systems and/or three way stopcocks, frequent catheter flushing with heparinized saline solutions, and minimizing the length of the procedure.
Serious or fatal reactions have been associated with the administration of iodine-containing radiopaque media. It is of utmost importance to be completely prepared to treat any contrast agent reaction. Caution must be exercised in patients with severely impaired renal function, combined renal and hepatic disease, combined renal and cardiac disease, severe thyrotoxicosis, myelomatosis, or anuria, particularly when large doses are administered. (See PRECAUTIONS.)
Intravascularly administered iodine-containing radiopaque media are potentially hazardous in patients with multiple myeloma or other paraproteinacious diseases, who are prone to disease-induced renal insufficiency and/or failure. Although neither the contrast agent nor dehydration has been proven to be the cause of renal insufficiency (or worsening renal insufficiency) in myelomatous patients, it has been speculated that the combination of both may be causative. Special precautions, including maintenance of normal hydration and close monitoring, are required. Partial dehydration in the preparation of these patients prior to injection is not recommended since this may predispose the patient to precipitation of the myeloma protein.
Reports of thyroid storm following the intravascular use of iodinated radiopaque agents in patients with hyperthyroidism, or with an autonomously functioning thyroid nodule, suggest that this additional risk be evaluated in such patients before use of any contrast agent.
Administration of radiopaque materials to patients with known or suspected pheochromocytoma should be performed with extreme caution. If, in the opinion of the physician, the possible benefits of such procedures outweigh the considered risks, the procedures may be performed; however, the amount of radiopaque medium injected should be kept to an absolute minimum. The blood pressure should be assessed throughout the procedure and measures for treatment of a hypertensive crisis should be available. These patients should be monitored very closely during contrast enhanced procedures.
THE DECISION TO USE CONTRAST ENHANCEMENT IS ASSOCIATED WITH RISK AND INCREASED RADIATION EXPOSURE, AND SHOULD BE BASED UPON A CAREFUL EVALUATION OF CLINICAL, OTHER RADIOLOGIC DATA, AND THE RESULTS OF UNENHANCED CT FINDINGS.
Patients receiving contrast agents, and especially those who are medically unstable, must be closely supervised. Diagnostic procedures which involve the use of iodinated intravascular contrast agents should be carried out under the direction of personnel skilled and experienced in the particular procedure to be performed. A fully equipped emergency cart, or equivalent supplies and equipment, and personnel competent in recognizing and treating adverse reactions of all types should always be available. Since severe delayed reactions have been known to occur, emergency facilities and competent personnel should be available for at least 30 to 60 minutes after administration. Dehydration, Renal Insufficiency, Congestive Heart Failure: Preparatory dehydration is dangerous and may contribute to acute renal failure in patients with advanced vascular disease, congestive heart disease, diabetic patients, and other patients such as those on medications which alter renal function and the elderly with age related renal impairment. Patients should be adequately hydrated prior to and following the intravascular administration of iodinated contrast agents. Dose adjustments in renal impairment have not been studied.
Iodinated contrast agents may cross the blood-brain barrier. In patients where the blood-brain barrier is known or suspected to be disrupted, or in patients with normal blood-brain barriers and associated renal impairment, CAUTION MUST BE EXERCISED IN CONSIDERING THE USE OF AN IODINATED CONTRAST AGENT. (See Pharmacodynamics.)
Patients with congestive heart failure receiving concurrent diuretic therapy may have relative intravascular volume depletion, which may affect the renal response to the contrast agent osmotic load. Such patients should be observed for several hours following the procedure to detect delayed hemodynamic renal function disturbances.
Immunologic Reactions: The possibility of a reaction, including serious, life-threatening, fatal, anaphylactoid or cardiovascular reactions, should always be considered. Increased risk is associated with a history of previous reaction to a contrast agent, a known sensitivity to iodine and known allergies (i.e., bronchial asthma, hay fever and food allergies) other hypersensitivities, and underlying immune disorders, autoimmunity or immunodeficiencies that predispose to specific or non-specific mediator release.
Skin testing cannot be relied upon to predict severe reactions and may itself be hazardous to the patient. A thorough medical history with emphasis on allergy and hypersensitivity, immune, autoimmune and immunodeficiency disorders, and prior receipt of and response to the injection of any contrast agent, may be more accurate than pretesting in predicting potential adverse reactions. Premedication with antihistamines or corticosteroids to avoid or minimize possible allergic reactions does not prevent serious life-threatening reactions, but may reduce both their incidence and severity Extreme caution should be exercised in considering the use of iodinated contrast agents in patients with these histories or disorders.
Anesthesia: General anesthesia may be indicated in the performance of some procedures in selected patients; however, a higher incidence of adverse reactions has been reported in these patients. It is not clear if this is due to the inability of the patient to identify untoward symptoms, or to the hypotensive effect of anesthesia, which can prolong the circulation time and increase the duration of exposure to the contrast agent.
Angiography: In angiographic procedures, the possibility of dislodging plaques or damaging or perforating the vessel wall with resultant pseudoaneurysms, hemorrhage at puncture site, dissection of coronary artery etc., should be considered during catheter manipulations and contrast agent injection. Angiography may be associated with local and distal organ damage, ischemia, thrombosis and organ failure (e.g., brachial plexus palsy, chest pain, myocardial infarction, sinus arrest, hepato-renal function abnormalities, etc.). Test injections to insure proper catheter placement are suggested. Increased thrombosis and activation of the complement system have also occurred. (See WARNINGS.) Angiography also should be avoided whenever possible in patients with homocystinuria because of the risk of inducing thrombosis and embolism. (See Pharmacodynamics.)
Selective coronary arteriography should be performed only in selected patients and those in whom the expected benefits outweigh the procedural risk. Also, the inherent risks of angiocardiography in patients with chronic pulmonary emphysema must be weighed against the necessity for performing this procedure.
Venography: The safety of ioxilan (ioxilan (ioxilan) ) in venographic procedures has not been studied.
Extreme caution during injection of a contrast agent is necessary to avoid extravasation. This is especially important in patients with severe arterial or venous disease.
General Adverse Reactions To Contrast Agents
The following adverse reactions are possible with any parenterally administered iodinated contrast agent. Severe life-threatening reactions and fatalities, mostly of cardiovascular origin, have occurred. Most deaths occur during injection or 5 to 10 minutes later; the main feature being cardiac arrest with cardiovascular disease as the main aggravating factor. Isolated reports of hypotensive collapse and shock are found in the literature. Based upon clinical literature, reported deaths from the administration of other iodinated contrast agents range from 6.6 per 1 million (0.00066 percent) to 1 in 10,000 patients (0.01 percent).
The reported incidence of adverse reactions to contrast agents in patients with a history of allergy is twice that of the general population. Patients with a history of previous reactions to a contrast agent are three times more susceptible than other patients. However, sensitivity to contrast agents does not appear to increase with repeated examinations.
Adverse reactions to injectable contrast agents fall into two categories: chemotoxic reactions and idiosyncratic reactions. Chemotoxic reactions result from the physicochemical properties of the contrast agent, the dose and the speed of injection. All hemodynamic disturbances and injuries to organs or vessels perfused by the contrast agent are included in this category. Idiosyncratic reactions include all other reactions. They occur more frequently in patients 20 to 40 years old.
Idiosyncratic reactions may or may not be dependent on the dose injected, the speed of injection, the mode of injection and the radiographic procedure. Idiosyncratic reactions are subdivided into minor, intermediate and severe. The minor reactions are self-limited and of short duration; the severe reactions are life-threatening and treatment is urgent and mandatory.
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Long-term animal studies have not been performed with ioxilan (ioxilan (ioxilan) ) to evaluate carcinogenic potential or effects on fertility. Ioxilan (ioxilan (ioxilan) ) was not genotoxic in a series of studies including the Ames test, an in vitro human lymphocytes analysis of chromosomal aberrations, an in vivo mouse micronucleus assay, and in an in vivo mouse dominant lethal assay.
Teratogenic Effects: Pregnancy Category B
Reproduction studies performed with ioxilan (ioxilan (ioxilan) ) injection in rats at doses up to 6.5 gl/kg (3.7 times the recommended dose for a 50 kg human, or approximately 0.7 times the human dose following normalization of the data to body surface area estimates) and rabbits at doses up to 3.5 gl/kg (2 times the recommended dose for a 50 kg human, or approximately the same as the human dose following normalization of the data to body surface area estimates) did not reveal evidence of direct harm to the fetus. Embryolethality was not detected. Adequate and well-controlled studies in pregnant women have not been conducted. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.
It is not known whether ioxilan (ioxilan (ioxilan) ) is excreted in human milk. However, many injectable contrast agents are excreted unchanged in human milk. Although it has not been established that serious adverse reactions occur in nursing infants, caution should be exercised when intravascular contrast media are administered to nursing women because of potential adverse reactions, and consideration should be given to temporarily discontinuing nursing.
Safety and effectiveness in children have not been established.
Last reviewed on RxList: 2/25/2009
This monograph has been modified to include the generic and brand name in many instances.
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