Omniscan

Uses

CNS (Central Nervous System): Omniscan is a gadolinium-based contrast agent used for intravenous use in MRI to visualize lesions with abnormal vascularity (or those thought to cause abnormalities in the blood-brain barrier) in the brain (intracranial lesions), spine, and associated tissues.

Body (Intrathoracic [noncardiac], Intra-abdominal, Pelvic And Retroperitoneal Regions): Omniscan is a gadolinium-based contrast agent used for intravenous use in MRI to facilitate the visualization of lesions with abnormal vascularity within the thoracic (noncardiac), abdominal, pelvic cavities, and the retroperitoneal space.

How Omniscan works

Based on the behavior of protons when placed in a strong magnetic field, which is interpreted and transformed into images by magnetic resonance (MR) instruments. Paramagnetic agents have unpaired electrons that generate a magnetic field about 700 times larger than the proton's field, thus disturbing the proton's local magnetic field. When the local magnetic field around a proton is disturbed, its relaxation process is altered. MR images are based on proton density and proton relaxation dynamics. MR instruments can record 2 different relaxation processes, the T1 (spin-lattice or longitudinal relaxation time) and the T2 (spin-spin or transverse relaxation time). In magnetic resonance imaging (MRI), visualization of normal and pathological brain tissue depends in part on variations in the radiofrequency signal intensity that occur with changes in proton density, alteration of the T1, and variation in the T2. When placed in a magnetic field, gadodiamide shortens both the T1 and the T2 relaxation times in tissues where it accumulates. At clinical doses, gadodiamide primarily affects the T1 relaxation time, thus producing an increase in signal intensity. Omniscan does not cross the intact blood-brain barrier; therefore, it does not accumulate in normal brain tissue or in central nervous system (CNS) lesions that have not caused an abnormal blood-brain barrier (e.g., cysts, mature post-operative scars). Abnormal vascularity or disruption of the blood-brain barrier allows accumulation of gadodiamide in lesions such as neoplasms, abscesses, and subacute infarcts.

Dosage

Omniscan dosage

No special preparation of the patient is required. Omniscan should be drawn into the syringe immediately before use.The vial is intended for one patient only. Contrast medium not used in one examination must be discarded. CNS (Central Nervous System):

• Adults: The recommended dose of Omniscan is 0.2 mL/kg (0.1 mmol/kg) administered as a bolus intravenous injection.
• Pediatric Patients (2-16 years): The recommended dose of Omniscan is 0.2 mL/kg (0.1 mmol/kg) administered as a bolus intravenous injection.

Body (Intrathoracic [noncardiac], Intra-abdominal, Pelvic And Retroperitoneal Regions):

• Adult and Pediatric Patients (2-16 years of age): For imaging the kidney, the recommended dose of Omniscan is 0.1 mL/kg (0.05 mmol/kg). For imaging the intrathoracic (noncardiac), intra-abdominal, and pelvic cavities, the recommended dose of Omniscan is 0.2 mL/kg (0.1 mmol/kg)

Side Effects

Nephrogenic systemic fibrosis, Hypersensitivity reactions

Precaution

Gadolinium-based contrast agents (GBCAs) increase the risk for nephrogenic systemic fibrosis (NSF) among patients with impaired elimination of the drugs. Avoid use of GBCAs among these patients unless the diagnostic information is essential and not available with non-contrast enhanced MRI or other modalities.

The GBCA-associated NSF risk appears highest for patients with chronic, severe kidney disease (GFR < 30 mL/min/1.73m2) as well as patients with acute kidney injury. Screen patients for acute kidney injury and other conditions that may reduce renal function.

Interaction

There are no known drug interactions and none well documented.

Food Interaction

Omniscan Hypertension interaction

[Major] Gadolinium- based contrast agents (GBCAs) such as gadopentetate dimeglumine, gadoteridol and gadodiamide are contraindicated in patients with chronic, severe kidney disease (glomerular filtration rate, GFR 60 years, hypertension or diabetes).

Always estimate the glomerular filtration rate (GFR) through laboratory testing.

Omniscan Drug Interaction

Unknown: aspirin, aspirin, amoxicillin, amoxicillin, amoxicillin / clavulanate, amoxicillin / clavulanate, celecoxib, celecoxib, ciprofloxacin, ciprofloxacin, deferoxamine, deferoxamine, ginkgo, ginkgo, acetaminophen, acetaminophen, tamoxifen, tamoxifen

Omniscan Disease Interaction

Major: renal impairmentModerate: allergies

Volume of Distribution

• 200 ± 61 mL/kg

Half Life

Two-compartment model with mean distribution and elimination half-lives (reported as mean ± SD) of 3.7 ± 2.7 minutes and 77.8 ± 16 minutes, respectively.

Clearance

• Renal cl=1.7 mL/min/kg
• Plasma cl=1.8 mL/min/kg

Elimination Route

Omniscan is eliminated primarily in the urine.

Pregnancy & Breastfeeding use

Pregnancy category B3. No effects of Omniscan on reproductive performance were seen in rats at doses up to 1.0 mmol/kg. In rabbits, there is an increased incidence of litters with skeletal or visceral abnormalities at doses up to 0.5 and 1.0 mmol/kg. However, these effects are possibly attributable to maternal toxicity rather than a direct effect of the drug. There are no adequate and well-controlled studies of Omniscan in pregnant women. Omniscan should be used in pregnancy only if the potential benefit justifies the potential risk to the foetus.

Use in Lactation: It is not known whether Omniscan is excreted in human milk. Breast-feeding should be discontinued prior to administration and should not be recommenced until at least 24 hours after the administration of Omniscan.

Contraindication

Chronic, severe kidney disease (glomerular filtration rate < 30 ml/ min/1.73 m2), or acute kidney injury prior hypersensitivity reaction, should not be used in patients known to have hypersensitivity to Omniscan or its constituents.

Special Warning

Use in Children: The safety and effectiveness of Omniscan have been established for whole body magnetic resonance imaging in children from 6 months of age.The safety and effectiveness in infants and neonates have been established in the evaluation of lesions within the brain and spine.

There is no experience with Omniscan in children below 6 months of age with severe hepatic or renal disease, or with premature infants below 4 weeks, or those with a post-conceptional age of less than 30 weeks.

Use in elderly patients: Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection and it may be useful to monitor renal function.

Acute Overdose

Clinical consequences of overdose have not been reported and acute symptoms of toxicity are unlikely in patients with a normal renal function. Treatment is symptomatic. There is no antidote for this contrast medium. In patients with delayed elimination due to renal insufficiency and in patients who have received excessive doses, the contrast medium can be eliminated by haemodialysis.

Storage Condition

Store at temperatures not exceeding 25° C. Protect from light.

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