Singapore Drugs Database

Indication

For diagnostic use only. Indicated for adults and children age 2 and over for contrast enhancement during cranial and spinal MRI, and for contrast-enhanced magnetic resonance angiography (CE-MRA). Gadobutrol is particularly suited for the detection of very small lesions and for the visualization of tumors that do not readily take up contrast media. It may be a desired agent when the exclusion or demonstration of an additional pathology may influence the choice of therapy or patient management. It may also be suitable for perfusion studies in the diagnosis of stroke, detection of focal cerebral ischemia, and in studies of tumor perfusion.

Mechanism of Action

MRI tissue visualization is dependent, in part, on variations in intensity of radiofrequency signals which occur due to differences in proton density, differences of the spin-lattice or longitudinal relaxation times (T1), and differences in the spin-spin or transverse relaxation times (T2). Gadolinium shortens T1 and T2 relaxation times. Greater signal enhancement is achieved with increased shortening of T1 and T2. The extent to which Gadolinium can shorten T1 and T2 is influenced by concentration in tissue, MRI field strength, and the relative ratio of transverse and longitudinal relaxation times. The recommended dose produced the greatest sensitivity of T1 shortening effect in T1-weighted magnetic resonance sequences. In T2-weighted sequences, the large magnetic moment of gadolinium induced local magnetic field inhomogenenities. At high concentrations used during bolus injections, T2-weighted sequences show a signal decrease.

Pharmacokinetics

Absorption

With normal renal function, the AUC is 1.1 ± 0.1 mmol·h/L.

Distribution

Rapid distribution to extracellular space occurs after intravenous administration. After a dose of 0.1mmol/kg body weight, an average plasma level of 0.59 mmol/L was measured 2 minutes post injection, and 0.3mmol/L 60 minutes post injection.

Metabolism

Gadobutrol is not metabolized.

Elimination

Clearance

In healthy subjects, renal clearance is 1.1 - 1.7mL/(min·kg). Within 2 hours of intravenous injection more than 50% is eliminated via the urine. Within 12 hours more than 90% of the given dose is eliminated. Clearance was observed to be slightly lower in elderly subjects, when using a 0.1mmol/kg dose. In the pediatric population, the median AUC, clearance and elimination half life was observed to be similar across the age range of 2-17, based on a population pharmacokinetic analysis of 130 pediatric subjects aged 2-17. In children aged 2-6 (n=45) the median AUC of gadobutrol was 0.8 mmol·h/L, the median clearance was 0.13L/hr/kg, and the median elimination half life was 1.75h. In children aged 7-11 (n=39) the median AUC of gadobutrol was 1.0 mmol·h/L, the median clearance was 0.1L/hr/kg, and the median elimination half life was 1.61h. In children aged 12-17 (n=46) the median AUC of gadobutrol was 1.2 mmol·h/L, the median clearance was 0.09 L/hr/kg, and the median elimination half life was 1.65h. Approximately 99% (median value) of the dose was recovered in the urine after 6 hours. A prolonged serum half life of gadobutrol is correlated with a reduction in creatinine clearance. In patients with mild-moderate renal impairment (80>CLCR>30 mL/min) the elimination half life was 5.8 ± 2.4 hours, the AUC was 4.0 ± 1.8 mmol·h/L, and complete recovery from the urine is seen within 72 hours. In patients with severe renal impairment (CLCR

Toxicity

Lethality was observed in rodents after a single intravenous administration of 20 mmol/kg. This represents a dose of at least 2 orders of magnitude higher than the standard single diagnostic dose in humans (0.1 mmol/kg). No carcinogenicity studies have been conducted. No mutagenesis was observed in vitro in reverse mutation tests in bacteria, or in the HGPRT (hypoxanthine-guanine phosphoribosyl transferase) test using Chinese hamster V79 cells. Similarly, no mutagenesis was seen in chromosome abberation tests of human peripheral blood lymphocytes. It was also negative in in-vivo micronucleus tests in mice following a 0.5mmol/kg intravenous injection. No fertility or reproductive impairment was observed in male and female rates given doses 12.2 times human equivalent doses, based on body surface area. Intolerance reactions local to the injection site have been observed in rabbits after paravenous administration, and are associated with the infiltration of inflammatory cells, suggesting the possibility of local irritation if the contrast medium leaks around veins in a clinical setting.

Active Ingredient/Synonyms

gadolinium(III) 2,2',2''-(10-((2R,3S )-1,3,4-trihydroxybutan-2-yl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetate | Gadobutrol |