Administration of iodinated contrast agents may interfere with thyroid uptake of radioactive iodine (I-131 and I-123) and decrease therapeutic and diagnostic efficacy in patients with carcinoma of the thyroid. The decrease in efficacy lasts for 6-8 weeks.
- Beta-adrenergic Blocking Agents
The use of beta-adrenergic blocking agents lowers the threshold for and increases the severity of contrast reactions, and reduces the responsiveness of treatment of hypersensitivity reactions with epinephrine. Because of the risk of hypersensitivity reactions, use caution when administering OMNIPAQUE to patients taking beta-blockers.
Effect on Thyroid Tests
If iodine-containing isotopes are to be administered for the diagnosis of thyroid disease, the iodine-binding capacity of thyroid tissue may be reduced for up to 2 weeks after contrast agent administration. Thyroid function tests which do not depend on iodine estimation, e.g., T3 resin uptake or direct thyroxine assays, are not affected.
Risk Summary
Postmarketing data with OMNIPAQUE use in pregnant women are insufficient to determine if there is a drug-associated risk of adverse developmental outcomes. Iohexol crosses the placenta and reaches fetal tissues in small amounts (see Data). In animal reproduction studies, no adverse developmental effects were observed following intravenous iohexol administration to pregnant rats and rabbits during organogenesis at doses up to 0.4 (rat) and 0.5 (rabbit) times the maximum recommended human intravenous dose (see Data).
The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defects, loss or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.
Data
Human Data
Literature reports show that iohexol crosses the placenta and is visualized in the digestive tract of exposed infants after birth.
Animal Data
Reproduction studies were performed in rats and rabbits with intravenous administration of iohexol at the following dose levels: 1.0, 2.0, 4.0 g iodine/kg in rats, in 3 groups of 25 dams once daily during days 6 through 15 of pregnancy; 0.3, 1.0, 2.5 g iodine/kg in rabbits, in 3 groups of 18 doses once a day during days 6 through 18 of pregnancy. Iohexol was not embryotoxic or teratogenic in either species at the dose levels tested.
Risk Summary
The literature reports that breast feeding after iohexol administration to the mother would result in the infant receiving an oral dose of approximately 0.7% of the maternal intravenous dose. There is no information on the effects of the drug on milk production. Iodinated contrast agents are excreted unchanged in human milk in very low amounts with poor absorption from the gastrointestinal tract of a breastfed infant. Exposure to iohexol to a breastfed infant can be minimized by temporary discontinuation of breastfeeding (see Clinical Considerations). The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for OMNIPAQUE and any potential adverse effects on the breastfed infant from OMNIPAQUE or from the underlying maternal condition.
Clinical Considerations
Interruption of breastfeeding after exposure to iodinated contrast agents is not necessary because the potential exposure of the breastfed infant to iodine is small. However, a lactating woman may consider interrupting breastfeeding and pumping and discarding breast milk for 10 hours (approximately 5 elimination half-lives) after OMNIPAQUE administration to minimize drug exposure to a breastfed infant.
Distribution
In 16 adult subjects (receiving between 500 mg iodine/kg to 1500 mg iodine/kg intravenous iohexol) the volume of distribution was165 (108-219) mL/kg.
Elimination
Metabolism
No significant metabolism, deiodination or biotransformation occurs.
Excretion
Following intravascular injection, iohexol is excreted unchanged by glomerular filtration. 90% or more of the injected iohexol dose is excreted within the first 24 hours, with the peak urine concentrations occurring in the first hour after administration.
Specific Populations
Renal Impairment
In patients with renal impairment, greater plasma iohexol exposure may be anticipated due to slowed elimination of iohexol. In these patients, as well as in infants with immature kidneys, fecal excretion of iohexol may occur.
OMNIPAQUE Clinical Studies for CT
The safety and efficacy of intravenously administered OMNIPAQUE for CT of the head and body were evaluated in six clinical studies (Table 3). Each study also used an ionic high-osmolar iodinated contrast agent as a comparator (Table 3). Patients were randomized to administration of either OMNIPAQUE or the comparator. OMNIPAQUE patients had a mean age of 53 years (range 16 to 85), were 44% women, had a mean weight of 67 kg (range 36 to 134), and were administered a mean of 572 mg iodine/kg (range 176-1250); comparator patients had a mean age of 51 years (range 14 to 80), were 43% women, had a mean weight of 70 kg (range 40 to 136), and were administered a mean of 484 mg iodine/kg (range 135 to 1500). In three studies, efficacy was determined from investigator ratings of quality of contrast enhancement (none, poor, good, or excellent; only scans rated as good or excellent were considered diagnostic); in the remaining three studies, efficacy was assessed quantitatively through X-ray attenuation, measured pre-contrast and at various time points post-contrast.
The percentage of scans rated as good or excellent was 100% for both OMNIPAQUE and the comparator in each of the two studies, and 79% for OMNIPAQUE and 74% for the comparator in the third study. In the studies that measured X-ray attenuation, there were no clinically significant differences between OMNIPAQUE and the comparator regarding contrast over time or time to maximal attenuation.
Overall, the incidence of discomfort (heat, pain, cold, tingling, pressure, chest heaviness, or cramp) was lower in the patients receiving OMNIPAQUE, with 115 (38%) of 300 patients receiving OMNIPAQUE vs. 177 (60%) of 295 comparator patients reporting discomfort ionic media (p<0.001). Similarly, fewer patients receiving OMNIPAQUE than comparator patients reported adverse events (7% versus 19%, respectively, p<0.001).
Table 3| Study | Indication | OMNIPAQUE (mg iodine/mL) | No. of Patients Receiving OMNIPAQUE | Comparator (mg iodine/mL) | Patients Receiving Comparator |
|---|
| 1 | Intracranial | 300 | 26 | Diatrizoate (282) | 23 |
| 2 | | 300 | 16 | Iothalamate (282) | 15 |
| 3 | | 350 | 30 | Metrizoate (350) | 30 |
| 4 | | 240 | 100 | Diatrizoate (168) | 100 |
| 5 | Abdominal | 350 | 28 | Metrizoate (350) | 27 |
| 6 | | 300 | 100 | Metrizoate (280) | 100 |
| TOTAL | | | 300 | | 295 |
Hypersensitivity Reactions
Advise the patient concerning the risk of hypersensitivity reactions that can occur both during and after OMNIPAQUE administration. Advise the patient to report any signs or symptoms of hypersensitivity reactions during the procedure and to seek immediate medical attention for any signs or symptoms experienced after discharge [see Warnings and Precautions (5.2)]
Advise patients to inform their physician if they develop a rash after receiving OMNIPAQUE [see Warnings and Precautions (5.9)].
Contrast Induced Acute Kidney Injury
Advise the patient concerning appropriate hydration to decrease the risk of contrast induced acute kidney injury [see Warnings and Precautions (5.3)].
Extravasation
If extravasation occurs during injection, advise patients to seek medical care for progression of symptoms [see Warnings and Precautions (5.5)].
Lactation
Advise a lactating woman that interruption of breastfeeding is not necessary, however, to avoid any exposure a lactating woman may consider pumping and discarding breast milk for 10 hours after OMNIPAQUE administration [see Use in Specific Populations (8.2)].
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or
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OMNIPAQUE is a trademark of GE Healthcare or one of its subsidiaries.
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Revised November 2017
ONC-5C-CORK