Lopidam370 mg/ml

Lopidam is a radiographic contrast agent (not a therapeutic drug) that is administered to enhance the visibility of internal structures, blood vessels, and organs during x-ray based imaging procedures. Its use is classified below by strength of evidence.

Established/FDA-approved uses

• Intravascular use: cerebral and peripheral arteriography, coronary arteriography and left ventriculography (cardiac angiography), visceral (abdominal) angiography, excretory urography, contrast-enhanced computed tomography (CT) of the head and body, and venography.
• Intrathecal use (specific formulations only): myelography of the lumbar, thoracic, and cervical regions, and adjunctively for CT of the head and spine following intrathecal administration.
• Other: arthrography (joint imaging).

Notes on use

Lopidam is used strictly for diagnostic imaging under the supervision of a qualified radiologist or physician; it has no independent therapeutic effect. The specific concentration and formulation of Lopidam used (e.g., for intravascular versus intrathecal procedures) must match the intended route of administration, as formulations are not interchangeable.

Each mL of injectable solution contains Iopamidol in concentrations corresponding to 200, 250, 300, or 370 mg of organically bound iodine per mL (equivalent to approximately 408 mg, 510 mg, 612 mg, or 755 mg of Iopamidol per mL respectively), formulated as a sterile, non-pyrogenic, aqueous solution for injection with small amounts of a chelating agent (e.g., edetate calcium disodium) and buffering agents such as tromethamine.

Iopamidol contains no free iodine and is a non-ionic monomer, which contributes to its low osmolality compared with older ionic contrast agents.

Lopidam is a triiodinated, non-ionic, water-soluble radiographic contrast medium belonging to the low-osmolar contrast agent (LOCM) category. It is chemically a substituted derivative of 5-amino-2,4,6-triiodoisophthalic acid.

Lopidam is supplied as a clear, colorless to pale yellow sterile solution for intravascular, intrathecal, or intra-articular injection, depending on the specific product concentration. It works purely through its physical property of attenuating x-rays (due to its iodine content), allowing radiographic differentiation of vascular structures, organs, and body cavities from surrounding tissue.

Lopidam belongs to the class of non-ionic, low-osmolar, monomeric iodinated radiographic (x-ray) contrast media used in diagnostic imaging.

Mechanism

Iopamidol has no pharmacodynamic or therapeutic activity in the conventional sense. Its radiographic effect derives from the physical property of iodine atoms to absorb x-rays, which increases radiodensity and thereby improves visualization of blood vessels, organs, and other structures on imaging.

Pharmacokinetics

• Distribution: After intravascular injection, Iopamidol distributes rapidly into the extracellular fluid compartment; it does not cross an intact blood-brain barrier or bind significantly to plasma proteins.
• Metabolism: Iopamidol is not metabolized in the body.
• Excretion: It is eliminated essentially unchanged by the kidneys via glomerular filtration, with over 90% of an intravascular dose excreted in the urine within 24 hours in patients with normal renal function.
• Half-life: Approximately 2 hours in individuals with normal renal function; prolonged in renal impairment.

Lopidam is administered only by or under the supervision of a physician trained in the procedure being performed, in a facility equipped with resuscitation equipment and trained personnel to manage acute hypersensitivity reactions.

• Administered by intravascular (intravenous or intra-arterial), intrathecal, or intra-articular injection depending on the formulation and indication; formulations for one route (e.g., Isovue-M for intrathecal use) must not be substituted for another route.
• Visually inspect the solution before use; do not use if particulate matter or discoloration is present.
• Some products may need to be warmed to body temperature before injection to reduce viscosity; follow product-specific instructions.
• Ensure adequate patient hydration before and after administration.
• Patients should be observed for at least 20-30 minutes after administration for delayed hypersensitivity reactions.

Clinically significant interactions with Lopidam include:

• Metformin (in patients with renal impairment): If contrast-induced acute kidney injury occurs, metformin can accumulate and increase the risk of lactic acidosis. Per institutional protocol, metformin is often withheld at the time of, or before, contrast administration in at-risk patients and resumed only after renal function is confirmed stable.
• Interleukin-2 (aldesleukin) therapy: Patients previously treated with interleukin-2 have an increased risk of delayed hypersensitivity-like reactions (fever, rash, flu-like symptoms) to iodinated contrast media including Lopidam.
• Beta-blockers: Patients on beta-blocker therapy may experience more severe or atypical hypersensitivity reactions to Lopidam and may respond poorly to standard epinephrine treatment for such reactions.

Adverse effects reported with Lopidam are generally described below by frequency and severity.

Common (usually mild and transient)

• Sensation of warmth or flushing
• Nausea, vomiting
• Altered taste (metallic taste)
• Headache
• Injection site pain or discomfort

Serious (uncommon but clinically important)

• Hypersensitivity/anaphylactoid reactions: urticaria, angioedema, bronchospasm, laryngeal edema, hypotension, and rarely anaphylactic shock (see Precautions and Warnings).
• Contrast-induced nephropathy/acute kidney injury, particularly in patients with pre-existing renal impairment or diabetes.
• Cardiac arrhythmias or hemodynamic changes, especially with intra-arterial cardiac angiography.
• Thyroid dysfunction/thyroid storm in susceptible individuals.
• Extravasation injury at the injection site (pain, swelling, and rarely tissue damage).
• Seizures (reported with intrathecal use).

Lopidam should be used during pregnancy only if clearly needed and if the potential diagnostic benefit justifies the potential risk to the fetus; a physician should be consulted before use in pregnancy, and alternative imaging modalities without ionizing radiation or iodinated contrast should be considered when feasible.

Iodinated contrast agents such as Lopidam are excreted into breast milk only in small amounts. Available data suggest the amount absorbed by a breastfeeding infant is low; however, a physician should be consulted, and interrupting breastfeeding for a short period after administration may be considered as a precaution.

• Hypersensitivity reactions: Severe, life-threatening anaphylactoid reactions can occur with Lopidam, even in patients with no prior history of contrast exposure or reaction. Administration must occur where personnel and equipment for emergency resuscitation are immediately available, and patients should be observed after injection.
• Renal impairment: Lopidam can cause contrast-induced nephropathy, particularly in patients with pre-existing renal disease, diabetes mellitus, dehydration, or advanced age. Adequate hydration before and after the procedure and use of the lowest effective dose are important preventive measures.
• Prior contrast reaction: Patients with a history of a previous reaction to iodinated contrast media are at increased risk of recurrence and may require premedication (e.g., corticosteroids, antihistamines) or an alternative imaging approach.
• Concurrent metformin use with renal impairment: See Interactions for management guidance.
• Asthma or significant allergy history: Associated with an increased risk of hypersensitivity reactions to Lopidam.
• Thyroid disease: Use with caution in patients with a history of thyroid disease; overt thyrotoxicosis is an absolute contraindication (see Contraindications).
• Intrathecal use: Only formulations specifically indicated for intrathecal administration should be used for myelography; caution is required in patients with a history of seizures.

Overdose of Lopidam may occur with excessive volume or repeated doses in a short period, and can potentiate the risk of contrast-induced nephropathy, cardiac and hemodynamic disturbances, and pulmonary edema. There is no specific antidote.

If overdose is suspected, seek immediate medical attention or contact emergency services/a poison control center. Management is supportive and may include monitoring of renal function, cardiovascular and respiratory status, and correction of fluid/electrolyte imbalance. Lopidam is dialyzable, and hemodialysis may be used to assist elimination in patients with significant renal impairment.

Store at room temperature (below 30°C), protected from light, and do not freeze. Keep out of reach of children.

• Renal impairment: Use the lowest effective dose of Lopidam and ensure adequate hydration; monitor renal function, especially in patients also taking metformin (see Interactions).
• Hepatic impairment: No specific dose adjustment is established; use with general caution.
• Elderly: May have reduced renal reserve and are at higher risk of contrast-induced nephropathy; use the lowest effective dose and ensure hydration.
• Diabetic patients: At increased risk of contrast-induced nephropathy, particularly if also on metformin or with underlying renal impairment.
• Pediatric patients: See Pediatric Uses.
• Pregnant/lactating women: See Pregnancy and Lactation.

Lopidam is administered as a single dose for the duration of a single diagnostic imaging procedure; it is not used as a repeated or chronic therapy. If a repeat imaging study requiring contrast is needed, an adequate interval should be allowed to permit renal clearance of the prior dose, particularly in patients with any degree of renal impairment.

Iopamidol is classified under: Iodinated contrast media; Non-ionic, low-osmolar contrast agents; Diagnostic radiographic/radiocontrast agents.

Iopamidol does not exert a pharmacological or therapeutic action on body tissues. Its mode of action is purely physical: the triiodinated benzene ring structure contains iodine atoms with a high atomic number that strongly absorb x-rays, increasing the radiographic density (radiopacity) of blood, tissue fluid, or spinal fluid into which it is introduced. This differential absorption allows blood vessels, organs, and cavities to be distinguished from surrounding structures on x-ray, CT, or fluoroscopic images.

Category B

Lopidam is used in pediatric patients, including neonates and infants, for various imaging procedures such as contrast-enhanced CT, angiography, and excretory urography, with the dose calculated on a body-weight basis and the concentration selected according to the child's age and the procedure performed.

Safety and efficacy have been established for a number of specific pediatric indications and formulations per labeling, but not for every possible use; the radiologist/pediatrician should weigh the diagnostic benefit against the risks (including radiation exposure and contrast-related adverse effects) for each child, and safety and efficacy for some specific uses have not been established in neonates and young infants.