Gadodiamide

Gadodiamide is indicated as a contrast medium for cranial and spinal resonance imaging (MRI) and for general MRI of the body after intravenous administration. Gadodiamide provides contrast enhancement and facilitates visualisation of abnormal structures or lesions in various parts of the body including the CNS.

This is a clear, colourless to slightly yellow aqueous solution containing Gadodiamide USP 287 mg/ml equivalent  to 0.5 mmol/ml. For Magnetic resonance imaging, visualization of normal and pathological brain and spinal tissue depends, in part, on variations in the radiofrequency signal intensity. Gadodiamide decreases both the T1 and T2 relaxation times in tissues where it is distributed. At clinical doses, the effect is primarily on the T1 relaxation time, and produces an increase in signal intensity.

No special preparation of the patient is required. Gadodiamide 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.

Dosage for adults and children: The recommended dosage is 0.1 mmol/kg body weight (equivalent to 0.2 ml/kg body weight) up to 100 kg. Above 100 kg body weight 20 ml is usually sufficient to provide diagnostically adequate contrast. The required dose should be administered as a single intravenous injection. To ensure complete injection of the contrast medium, the intravenous line may be flushed with 5 ml sodium chloride injection 0.9%.

Adults only: When brain metastases are suspected, a dosage of 0.3 mmol/kg body weight (equivalent to 0.6 ml/ kg body weight) can be administered up to 100 kg. Above 100 kg body weight a total of 60 ml is usually sufficient. The dose of 0.3 mmol/kg body weight can be administered as a bolus intravenous injection. In patients with equivocal scans after administration of the 0.1 mmol/kg body weight injection, a second bolus injection of 0.2 mmol/kg body weight (equivalent to 0.4 ml/kg body weight) may be of additional diagnostic value when administered within 20 minutes of the first injection.

Asymptomatic transitory increases in serum iron and bilirubin have been reported in patients receiving Gadodiamide. Gadodiamide should not be directly mixed with other drugs. A separate syringe and needle should be used.

Gadodiamide should not be used in patients known to have hypersensitivity to Gadodiamide or its constituents.

Discomfort with a general sensation of warmth, coolness or a sensation of local pressure or pain at the injection site were commonly (>1% and <10%) observed in clinical studies. Dizziness, nausea, headache and a perverted sense of taste or smell were reported less frequently, but also in >1% of patients.

Carcinogenesis, Mutagenesis, Impairment of Fertility: The results of three in vitro and one in vivo short-term genotoxicity assays were negative. No long-term studies have been performed to evaluate the carcinogenic potential of Gadodiamide. Gadodiamide had no effect on the fertility and general reproductive performance in rats or in teratology studies in rats and rabbits at doses that did not cause maternal toxicity.

Use in Pregnancy: Pregnancy category B3. No effects of Gadodiamide 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 Gadodiamide in pregnant women. Gadodiamide 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 Gadodiamide 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 Gadodiamide.

The accepted safety considerations and procedures that are required for magnetic resonance imaging are applicable when Gadodiamide is used for contrast enhancement. Administration of contrast media should be performed by qualified personnel familiar with the procedure and an appropriate technique should be utilised. The possibility of a reaction, including serious, life-threatening, fatal, anaphylactoid or cardiovascular or other idiosyncratic reactions should always be considered, especially in those patients with known clinical hypersensitivity or a history of asthma or other allergic respiratory disorders. A course of action should therefore be planned in advance; with necessary drugs and equipment available for immediate treatment should a serious reaction occur. Transitory changes in serum iron (within the normal range in the majority of cases) have been observed in some patients after administration of Gadodiamide. The clinical significance of this, if any, is not known but all patients in whom this effect was observed remained asymptomatic. Gadodiamide interferes with serum calcium measurements with some colorimetric (complexometric) methods commonly used in hospitals. It may also interfere with determinations of other electrolytes (e.g. iron). Thus it is recommended that such methods not be used for 12-24 hours after administration of Gadodiamide. If such measurements are necessary, the use of other methods is recommended. Diagnostic procedures involving the use of contrast agents should be conducted under supervision of a physician with the prerequisite training and a thorough knowledge of the procedure to be performed. If Gadodiamide is drawn into a disposable syringe it should be used immediately. If non-disposable equipment is used, scrupulous care should be taken to prevent residual contamination with traces of cleansing agents.

Data on the safety of repeated injections are not available. If the physician determines sequential or repeat examinations are required, a suitable time interval between administrations should be observed to allow for clearance of the drug from the body. In some patients with severely impaired renal function (GFR<10 ml/min), further small reductions in GFR and increases in serum creatinine have been observed after administration of Gadodiamide. Since the clinical relevance of these findings is not fully known, care should be exercised before using Gadodiamide in such patients.

Use in Children: The safety and effectiveness of Gadodiamide 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 Gadodiamide 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.

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. 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.

Contrast medium for diagnostic procedures

Gadodiamide should be stored at room temperature (below 30°C) and protected from light. The vial is intended for one patient only. Any unused portion must be discarded.