OMNISCAN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for OMNISCAN (OMNISCAN).
Gadodiamide is a paramagnetic contrast agent that shortens T1 and T2 relaxation times in tissues, enhancing signal intensity in magnetic resonance imaging (MRI) by increasing the relaxation rate of water protons.
| Metabolism | Gadodiamide is not metabolized; it is eliminated unchanged by the kidneys via glomerular filtration. |
| Excretion | Primarily renal (glomerular filtration); >95% excreted unchanged in urine within 24 hours; <0.5% fecal. In renal impairment, elimination is prolonged, with increased biliary/fecal excretion possible. |
| Half-life | Normal renal function: terminal elimination half-life 1.5-2.5 hours. In renal impairment (e.g., GFR <30 mL/min): prolonged up to 18-72 hours, increasing risk of nephrogenic systemic fibrosis (NSF). |
| Protein binding | Negligible (less than 1%); no significant binding to plasma proteins. |
| Volume of Distribution | Approximately 0.2-0.3 L/kg (distributes primarily in extracellular fluid; minimal intracellular penetration). |
| Bioavailability | Not applicable for IV administration; 100% bioavailable intravascularly. No oral formulation available. |
| Onset of Action | IV administration: contrast enhancement appears within seconds to minutes; maximal enhancement of CNS lesions at 3-7 minutes post-injection. |
| Duration of Action | Sufficient for imaging (typically 30-60 minutes); enhancement declines as gadodiamide distributes and is eliminated. Contrast may persist longer in renal impairment. |
0.2 mL/kg (0.1 mmol/kg) intravenously as a bolus injection. A second dose can be administered within 30 minutes for MRI of the CNS.
| Dosage form | INJECTABLE |
| Renal impairment | Contraindicated in patients with acute or chronic severe renal impairment (GFR < 30 mL/min/1.73m²) or hepatorenal syndrome. For patients with moderate impairment (GFR 30-59 mL/min/1.73m²), use minimum necessary dose and do not exceed 0.1 mmol/kg per dose. Do not administer if GFR < 15 mL/min/1.73m². |
| Liver impairment | Use with caution in patients with severe hepatic impairment due to potential for increased serum half-life; no specific Child-Pugh based dosing adjustments are established. Avoid use in hepatorenal syndrome. |
| Pediatric use | Neonates and infants: 0.2 mL/kg (0.1 mmol/kg) IV; single dose. Safety for repeated doses not established in children under 2 years. For children 2 years and older: same dose as adults. |
| Geriatric use | No specific dose adjustment, but consider renal function as elderly patients have decreased GFR; screen for renal impairment before use. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for OMNISCAN (OMNISCAN).
| Breastfeeding | Gadodiamide is excreted in human milk in very low concentrations (M/P ratio not determined; estimated <0.04% of maternal dose per day). Limited data suggest negligible risk to breastfed infant; however, due to potential for adverse effects (allergic reaction, gadolinium deposition), caution should be exercised. Discontinue breastfeeding or discontinue drug, taking into account importance of drug to mother. |
| Teratogenic Risk | Category C: Animal reproduction studies have shown an adverse effect on the fetus (e.g., delayed development, increased post-implantation loss) at doses 2.5-5 times the human dose. No adequate, well-controlled studies in pregnant women. Gadolinium crosses the placenta and may cause fetal harm; use only if clearly needed and benefit outweighs risk. First trimester: theoretical risk of fetal gadolinium deposition. Second/third trimester: risk of nephrogenic systemic fibrosis in fetus if mother receives high doses; avoid use in pregnancy unless essential diagnostic information cannot be obtained otherwise. |
■ FDA Black Box Warning
WARNING: NEPHROGENIC SYSTEMIC FIBROSIS (NSF) - Gadolinium-based contrast agents increase the risk of NSF in patients with acute or chronic severe renal insufficiency (GFR <30 mL/min/1.73m2) or acute kidney injury. Avoid use unless diagnostic information is essential and not available with non-contrast MRI. Screen patients for renal dysfunction; obtain GFR in high-risk patients.
| Serious Effects |
["History of hypersensitivity to gadodiamide or any component of the formulation","Severe renal impairment (GFR <30 mL/min/1.73m2) or acute kidney injury, unless diagnostic benefit outweighs risk"]
| Precautions | ["Nephrogenic systemic fibrosis (NSF) risk in patients with renal impairment","Acute kidney injury in patients with preexisting renal dysfunction","Hypersensitivity reactions including anaphylaxis","Extravasation may cause tissue irritation","Interference with serum calcium measurement using certain colorimetric methods"] |
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| Fetal Monitoring | Monitor maternal renal function (eGFR) prior to administration to assess risk of nephrogenic systemic fibrosis; in pregnancy, monitor fetal well-being via ultrasound if gadolinium exposure occurs. No specific fetal monitoring required after single dose, but consider serial growth scans if repeated exposure. |
| Fertility Effects | No adequate studies on fertility effects in humans. Animal studies showed no impairment of fertility at doses up to 2.5 times the human dose. |