MAGNILEK

Indications

• Magnetic resonance imaging (MRI)
• Computed tomography (CT) scans
• Angiography

Dosage

Children: Refer to the BNF for Children for paediatric dosing recommendations based on age and weight.

Adults: Refer to specific guidelines and protocols for adult dosing based on the imaging procedure being performed.

Mechanism of action

Dimeglumine works by increasing the contrast of images obtained during diagnostic imaging procedures. It does this by providing a higher concentration of iodine in the bloodstream, which absorbs X-rays more effectively than surrounding tissues. The iodine in dimeglumine enhances the contrast of tissues and vascular structures, enabling clearer imaging of organs and blood vessels.

Pharmacodynamics

The pharmacodynamics of dimeglumine is characterized by its ability to improve the contrast in imaging modalities. The compound is rapidly distributed in the vascular system, leading to enhanced visualization of blood vessels and organs. Its non-ionic nature reduces the likelihood of adverse reactions commonly associated with ionic contrast agents, such as allergic reactions and nephrotoxicity.

Pharmacokinetics

Dimeglumine is administered intravenously and is distributed throughout the vascular system. It is eliminated primarily via the kidneys. The pharmacokinetics involve rapid distribution and clearance, with peak plasma concentrations occurring shortly after administration. The compound has a short half-life, which allows for quick imaging procedures and minimizes prolonged exposure to contrast agents.

Contra-indications

• Hypersensitivity to dimeglumine or any of its components
• Severe renal impairment
• Dehydration
• Hyperthyroidism

Adverse effects

• Nausea
• Vomiting
• Dizziness
• Headache
• Allergic reactions including rash and itching
• Nephrotoxicity in patients with pre-existing renal conditions

Interactions

• Increased risk of nephrotoxicity when used with other nephrotoxic agents
• May interfere with thyroid function tests

Precautions

• Monitor renal function before and after administration, especially in patients with existing renal impairment
• Use caution in patients with a history of asthma or allergic reactions
• Ensure adequate hydration before administration

Pregnancy

The safety of dimeglumine in pregnancy has not been established. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether dimeglumine is excreted in human milk. Caution should be exercised when administering to nursing mothers.

Storage

Store at room temperature, away from light and moisture. Do not freeze.

Formulations

• Injection solution for intravenous use

Indications

• Magnetic resonance imaging (MRI) of the brain and spine
• MRI of the musculoskeletal system
• MRI of the abdomen and pelvis
• MRI angiography

Dosage

Children: Refer to BNF for Children for specific dosing information based on age and weight.

Adults: The usual dose for adults is 0.1 mmol/kg body weight, administered intravenously. For certain indications, higher doses may be used as per clinical guidance.

Mechanism of action

Gadopentetate works by shortening the T1 relaxation time of protons in the vicinity of the gadolinium ion. When administered intravenously, the paramagnetic gadolinium enhances the contrast of MRI images by increasing the signal intensity of the vascular and tissue structures. This effect allows for better differentiation between normal and abnormal tissues during imaging.

Pharmacodynamics

The pharmacodynamics of gadopentetate is primarily related to its ability to alter magnetic resonance properties of tissues. After administration, it distributes into the extracellular space and binds to serum proteins. The increased concentration of gadolinium in areas of interest leads to enhanced image contrast, particularly in tumors, inflammation, and vascular abnormalities.

Pharmacokinetics

Gadopentetate is rapidly distributed in the extracellular space after intravenous administration. It has a volume of distribution similar to that of plasma. The elimination half-life is approximately 1.5 to 2 hours, with the majority of the drug excreted unchanged by the kidneys. Due to its renal clearance, it is important to assess kidney function prior to administration in patients with renal impairment.

Contra-indications

• Known hypersensitivity to gadopentetate or any of its components
• Severe renal impairment (eGFR <30 mL/min)

Adverse effects

• Nausea
• Headache
• Dizziness
• Injection site reactions
• Gadolinium-based contrast agent nephrogenic systemic fibrosis (NSF) in patients with severe renal impairment

Interactions

• Other gadolinium-based contrast agents should not be used concurrently due to potential for increased risk of NSF
• Medications affecting renal function may increase the risk of adverse effects

Precautions

• Use with caution in patients with moderate renal impairment (eGFR 30-59 mL/min)
• Ensure adequate hydration before administration in at-risk populations
• Monitor renal function in patients with risk factors for renal impairment

Pregnancy

Gadopentetate should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. Limited data on use in pregnant women.

Breast-feeding

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

Storage

Store in a cool, dry place, protected from light. Do not freeze. Keep out of reach of children.

Formulations

• Gadopentetate dimeglumine solution for injection