"The U.S. Food and Drug Administration announced today that injectable drugs used in total parenteral nutrition (TPN) in critical shortage will be imported into the United States and available to patients this week.
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The need for myelographic examination should be carefully evaluated. Iopamidol should be administered with caution in patients with increased intracranial pressure or suspicion of intracranial tumor, abscess or hematoma, those with a history of convulsive disorder, severe cardiovascular disease, chronic alcoholism, or multiple sclerosis, and elderly patients.
Particular attention must be given to state of hydration, concentration of medium, dose, and technique used in these patients.
Contrast media may promote sickling in individuals who are homozygous for sickle cell disease when injected intravenously or intra-arterially. Although ISOVUE-M is not injected intravascularly, measurable plasma levels are attained after intrathecal administration of iopamidol.
If frankly bloody cerebrospinal fluid is observed, the possible benefits of a myelographic examination should be considered in terms of risk to the patient.
Patients on anticonvulsant medication should be maintained on this therapy.
Direct intracisternal or ventricular administration for standard radiography (without computerized tomographic enhancement) is not recommended. Inadvertent intracranial entry of a large or concentrated bolus of the contrast medium, which increases the risk of neurotoxicity, can be prevented by careful patient management. Also, effort should be directed to avoid rapid dispersion of the medium causing inadvertent rise to intracranial levels (e.g., by active patient movement). If such intracranial entry of the medium occurs, prophylactic anticonvulsant treatment with diazepam or barbiturates orally for 24 to 48 hours should be considered.
Use of medications that may lower the seizure threshold (phenothiazine derivatives, including those used for their antihistaminic properties; tricyclic antidepressants; MAO inhibitors; CNS stimulants; analeptics; antipsychotic agents) should be carefully evaluated. While the contributory role of such medications has not been established, some physicians have discontinued these agents at least 48 hours before and for at least 24 hours following intrathecal use. Focal and generalized motor seizures have been reported after intrathecal use of water-soluble contrast agents including iopamidol. In several of those cases reported with iopamidol, higher than recommended doses were employed. Therefore avoid:
- Deviations from recommended neuroradiologic procedure or patient management.
- Use in patients with a history of epilepsy unless medically justified.
- Intracranial entry of a bolus or premature diffusion of a high concentration of the medium.
- Failure to maintain elevation of the head during the procedure, on the stretcher, and in bed.
- Excessive and particularly active patient movement or straining.
Diagnostic procedures which involve the use of any radiopaque agent should be carried out under the direction of personnel with the prerequisite training and with a thorough knowledge of the particular procedure to be performed. Appropriate facilities should be available for coping with any complication of the procedure, as well as for emergency treatment of severe reaction to the contrast agent itself. After parenteral administration of a radiopaque agent, competent personnel and emergency facilities should be available for at least 30 to 60 minutes since severe delayed reactions may occur.
Preparatory dehydration is dangerous and may contribute to acute renal failure in patients with advanced vascular disease, diabetic patients, and in susceptible nondiabetic patients (often elderly with pre-existing renal disease). Patients should be well hydrated prior to and following iopamidol administration.
The possibility of a reaction, including serious, life-threatening, fatal, anaphylactoid or cardiovascular reactions, should always be considered (see ADVERSE REACTIONS). Patients at increased risk include those with a history of a previous reaction to a contrast medium, patients with a known sensitivity to iodine per se, and patients with a known clinical hypersensitivity (bronchial asthma, hay fever, and food allergies). The occurrence of severe idiosyncratic reactions has prompted the use of several pretesting methods. However, pretesting cannot be relied upon to predict severe reactions and may itself be hazardous for the patient. It is suggested that a thorough medical history with emphasis on allergy and hypersensitivity, prior to the injection of any contrast medium, may be more accurate than pretesting in predicting potential adverse reactions. A positive history of allergies or hypersensitivity does not arbitrarily contraindicate the use of a contrast agent where a diagnostic procedure is thought essential, but caution should be exercised. Premedication with antihistamines or corticosteroids to avoid or minimize possible allergic reactions in such patients should be considered (see CONTRAINDICATIONS). Reports indicate that such pretreatment does not prevent serious life-threatening reactions, but may reduce both their incidence and severity.
Pre-existing conditions, such as pacemakers or cardiac medications, specifically beta-blockers, may mask or alter the signs or symptoms of an anaphylactoid reaction, as well as masking or altering the response to particular medications used for treatment. For example, beta-blockers inhibit a tachycardiac response, and can lead to the incorrect diagnosis of a vasovagal rather than an anaphylactoid reaction. Special attention to this possibility is particularly critical in patients suffering from serious, life-threatening reactions.
The possibility of inducing bacterial meningitis in patients during intrathecal procedures should always be considered. To avoid bacterial contamination during spinal puncture, a sterile field should be maintained at all times.
If nondisposable equipment is used, scrupulous care should be taken to prevent residual contamination with traces of cleansing agents.
Carcinogenesis, Mutagenesis, Impairment of Fertility
Long-term studies in animals have not been performed to evaluate carcinogenic potential. No evidence of genetic toxicity was obtained in in vitro tests.
Teratogenic Effects - Pregnancy Category B
Reproduction studies have been performed in rats and rabbits at doses up to 2.7 and 1.4 times the maximum recommended human dose (1.48 gl/kg in a 50 kg individual), respectively, and have revealed no evidence of impaired fertility or harm to the fetus due to iopamidol. There are, however, no adequate and well-controlled studies in pregnant women. 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 this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when iopamidol is administered to a nursing woman.
See DOSAGE AND ADMINISTRATION section.
Last reviewed on RxList: 8/28/2012
This monograph has been modified to include the generic and brand name in many instances.
Additional Isovue-M Information
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