GADOSAM

Indications

• Magnetic resonance imaging (MRI) for the visualization of normal and pathological tissues
• Assessment of neoplasms
• Evaluation of abscesses
• Investigation of subacute infarcts

Dosage

Children: Refer to the BNF for Children for appropriate dosing information in paediatric patients.

Adults: Refer to specific guidelines or protocols for dosing in adults as provided in the BNF.

Mechanism of action

Gadodiamide acts as a paramagnetic molecule that develops a magnetic moment when exposed to a magnetic field. This magnetic moment modifies the relaxation rates of water protons nearby, allowing for improved contrast in MRI imaging of tissues where gadodiamide is present.

Pharmacodynamics

In MRI, the visualization of tissues is influenced by variations in radiofrequency signal intensity, which depend on changes in proton density and alterations in relaxation times (T1 and T2). Gadodiamide enhances the T1 relaxation time, leading to increased signal intensity in tissues where it accumulates, particularly in areas with disrupted blood-brain barriers or abnormal vascularity, such as tumors and abscesses.

Pharmacokinetics

The pharmacokinetic properties of gadodiamide in various lesions are not extensively characterized. However, as a paramagnetic agent, it is distributed in the body based on the vascularity of tissues and may accumulate in abnormal lesions. The distribution and elimination pathways of gadodiamide are influenced by its solubility and interactions with body fluids.

Adverse effects

• Headache
• Nausea
• Dizziness
• Injection site reactions
• Nephrogenic systemic fibrosis in patients with severe renal impairment

Precautions

• Use with caution in patients with renal impairment
• Monitor renal function in patients at risk for nephrogenic systemic fibrosis
• Ensure adequate hydration prior to administration

Pregnancy

Gadodiamide should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. Safety in pregnancy has not been established.

Breast-feeding

It is not known whether gadodiamide is excreted in human milk. Caution should be exercised when administering to a nursing woman.

Storage

Store at 20-25 degrees Celsius. Protect from light and keep in the original container. Do not freeze.

Formulations

• Solution for injection

Mechanism of action

Gadodiamide paramagnetic molecule that develops a magnetic moment when placed in a magnetic field. The magnetic moment alters the relaxation rates of water protons in its vicinity in the body. Its use in magnetic resonance imaging (MRI) allows to selectively increase contrast in tissues where gadodiamide accumulates.

Pharmacodynamics

In magnetic resonance imaging, visualization of normal and pathologic tissue depends in part on variations in the radiofrequency signal intensity. These variations occur due to: changes in proton density; alteration of the spin-lattice or longitudinal relaxation time (T1); and variation of the spin-spin or transverse relaxation time (T2). Gadodiamide is a paramagnetic agent with unpaired electron spins which generate a local magnetic field. As water protons move through this local magnetic field, the changes in the magnetic field experienced by the protons reorient them with the main magnetic field more quickly than in the absence of a paramagnetic agent. By increasing the relaxation rate, 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. Disruption of the blood-brain barrier or abnormal vascularity allows the accumulation of gadodiamide in lesions such as neoplasms, abscesses, and subacute infarcts. The pharmacokinetic parameters of gadodiamide in various lesions are not known.