Metrizoic acid functions as an X-ray contrast agent through its high iodine content. The mechanism of action of metrizoic acid is as an X-Ray Contrast Activity agent. The high atomic number of iodine (Z=53) provides excellent X-ray attenuation, allowing the compound to absorb X-rays more effectively than surrounding tissues. When administered intravenously or intra-arterially, metrizoic acid distributes through the vascular compartment and highlights blood vessels, organs, and other structures during imaging procedures. The compound's ionic nature and high osmolality contribute to its contrast-enhancing properties but also increase the risk of adverse reactions. Metrizoic acid was developed as an ionic monomeric contrast medium to address the limitations of earlier high-osmolality contrast media. The compound's ability to provide diagnostic-quality images made it useful for a variety of imaging procedures, including angiography, urography, and other radiographic studies. However, the development of safer, low-osmolality contrast agents has largely replaced metrizoic acid in clinical practice.

In vitro, metrizoic acid is characterized by its physicochemical properties rather than by traditional pharmacological activity. The compound's high iodine content provides the basis for its radiopacity. In vitro assays typically measure iodine content, osmolality, and viscosity to characterize the compound's suitability as a contrast agent. The compound displays high osmolality, which contributes to its contrast-enhancing properties but also increases the risk of adverse reactions. Metrizoic acid is an ionic contrast medium, and its ionic nature influences its distribution and elimination characteristics. In vitro studies may also assess the compound's stability, compatibility with other agents, and potential for protein binding. The compound's high osmolality, which is nearly five times plasma osmolality, is a key physicochemical property that influences its biological effects. However, detailed in vitro activity data for metrizoic acid is limited, as the compound is primarily characterized by its physical properties rather than by receptor or enzyme interactions.

In vivo, metrizoic acid is used as a diagnostic contrast agent for various imaging procedures. One study in 1976 demonstrated that metrizoic acid, when used for cardiac angiography, was well tolerated, with a total of 10,000 injections in 2,028 patients. The compound is administered intravenously or intra-arterially and rapidly distributes through the vascular compartment. It is excreted renally, with the majority of the dose eliminated in the urine within 24 hours. The compound's high osmolality can cause adverse effects, including pain at the injection site, flushing, nausea, and allergic reactions. In comparative studies, no differences in clinical side-effects were noticed between metrizoic acid and other contrast media, and no irreversible side-effects were recorded. However, the film contrast of jodamid was significantly better than that of metrizoic acid. Metrizoic acid is no longer in general clinical use due to the availability of safer, low-osmolality contrast agents.

In vitro assays for metrizoic acid focus on physicochemical characterization rather than traditional enzyme or receptor binding assays. The compound's high iodine content is measured using analytical techniques such as HPLC or spectrophotometry. Osmolality is measured using osmometry, which determines the concentration of osmotically active particles in solution. Viscosity is measured using viscometry, which assesses the resistance of the solution to flow. These physicochemical properties are critical for determining the compound's suitability as a contrast agent and its potential for adverse effects. In vitro stability studies assess the compound's degradation over time under various conditions. Compatibility studies evaluate the compound's interaction with other drugs or formulation components. The compound's protein binding can be assessed using equilibrium dialysis or ultrafiltration. However, as metrizoic acid is a contrast agent rather than a pharmacologically active drug, traditional receptor binding assays are not applicable.

In vitro cellular assays are not typically performed for contrast agents such as metrizoic acid, as the compound's mechanism of action is based on physical properties rather than cellular interactions. However, cell-based assays may be used to assess the compound's cytotoxicity or its effects on cell function. Endothelial cells or other cell types may be exposed to metrizoic acid at various concentrations, and cell viability is assessed using standard assays such as MTT or LDH release. The compound's effects on cellular function, such as changes in membrane potential or ion flux, may also be studied. However, given the compound's high osmolality, cellular assays are more likely to assess osmotic effects rather than specific pharmacological activity. The compound's risk of inducing allergic reactions may be studied in cellular models of immune activation. However, detailed cellular assay data for metrizoic acid is limited, as the compound is no longer in active clinical use.

In vivo animal experiments for metrizoic acid typically employ models of cardiovascular or urinary tract imaging. Animals such as dogs or rabbits are administered the contrast agent intravenously or intra-arterially, and imaging studies are performed to assess the quality of visualization of blood vessels or other structures. The compound's pharmacokinetics and biodistribution can be studied in animal models by measuring plasma concentrations and tissue distribution over time. In a porcine liver study, the pharmacokinetics of radiofrequency ablation with chemolipiodolization using miriplatin were compared with those of other agents. For toxicology studies, animals are administered metrizoic acid at various doses, and adverse effects such as allergic reactions, nephrotoxicity, or cardiotoxicity are assessed. One study in 1976 demonstrated that metrizoic acid, when used for cardiac angiography, was well tolerated in a large patient population. However, detailed animal study data for metrizoic acid is limited, as the compound is no longer in active clinical use.

The pharmacokinetic properties of metrizoic acid are characteristic of ionic, high-osmolality contrast agents. Following intravascular administration, the compound is rapidly distributed throughout the extracellular space. It does not cross the intact blood-brain barrier to a significant extent. The compound is not metabolized to a significant degree and is excreted unchanged in the urine by glomerular filtration. The elimination half-life of metrizoic acid is approximately 1-2 hours in patients with normal renal function. The compound's high osmolality can cause osmotic diuresis, which may affect the distribution and elimination of the drug. The pharmacokinetics of metrizoic acid may be altered in patients with renal impairment, requiring dose adjustments or alternative imaging strategies. The compound's molecular weight is 627.94. However, detailed pharmacokinetic data for metrizoic acid is limited, as the compound is no longer in active clinical use.

The toxicity profile of metrizoic acid is characteristic of ionic, high-osmolality contrast agents. The compound displays high osmolality and has a risk of inducing allergic reactions. Adverse effects associated with high-osmolality contrast agents include pain at the injection site, flushing, nausea, vomiting, and allergic reactions ranging from mild urticaria to anaphylaxis. In cardiac angiography studies, adverse effects included ventricular fibrillation (7 cases) and significant bradycardia/asystole (5 cases). Metrizoic acid has an intermediate toxicity profile, positioned between the least toxic diatrizoate and the 3.5x more toxic iothalamate. For research on contrast-induced cardiotoxicity, metrizoic acid offers a distinct, intermediate risk model compared to the lower-risk diatrizoate or the significantly higher-risk iothalamate. Nephrotoxicity is a concern with high-osmolality contrast agents, particularly in patients with preexisting renal impairment. The compound's approval by the FDA has been discontinued.

[1]. Hemodynamic and electrocardiographic consequences of high- and low-osmolality contrast agents for left ventricular angiography. Cathet Cardiovasc Diagn. 1988;14(3):143-9.

[2]. Iopentol in urography. A clinical comparison between iopentol and metrizoate includingdelayed reactions. Acta Radiol. 1992 Jul;33(4):368-73.

[3]. Contrast enhanced brain CT. Comparison between iohexol and metrizoate. Neuroradiology. 1983;24(4):213-5.

Pantothenic acid is a monocarboxylic acid used as a radioactive contrast agent. Pantothenic acid is a molecule used as a contrast agent. Due to its high osmotic pressure, it carries a high risk of allergic reactions. The U.S. Food and Drug Administration (FDA) has discontinued its approval for use. A 1976 study showed that pantothenic acid was well tolerated for use in cardiac angiography. Over a three-year period, 2028 patients undergoing cardiovascular angiography received 10,000 injections. With two exceptions, all complications occurred during injections into the right coronary artery. Seven cases of ventricular fibrillation and five cases of significant bradycardia/cardiac arrest were associated with pantothenic acid injections. Overall, patients tolerated the drug well during cardiac examinations. Pantothenic acid is a radioactive contrast agent. The mechanism of action of pantothenic acid is as an X-ray contrast agent. A diagnostic radiopaque agent, usually present in sodium salt form. See also: ... See more ...

---

Drug Indications
Used as a contrast agent.

---

Mechanism of Action
The mechanism of action of mecofluidic acid is as an X-ray contrast agent.

Metrizoic acid is an ionic monomeric iodinated contrast medium historically used for angiography and urography. It emerged in the 1960s as a pivotal contrast agent for cardiovascular and urinary tract imaging. Its development addressed critical limitations of earlier high-osmolality contrast media. Metrizoic acid displays high osmolality and has a risk of inducing allergic reactions. It has a molecular weight of 627.94. One study in 1976 demonstrated that metrizoic acid, when used for cardiac angiography, was well tolerated, with a total of 10,000 injections in 2,028 patients. However, the compound's approval by the FDA has been discontinued, and it is no longer in general clinical use. The development of safer, low-osmolality non-ionic contrast agents has replaced metrizoic acid in clinical practice. Metrizoic acid is now primarily of historical interest in the development of safer iodinated contrast media and is used as a research tool for studying contrast-induced toxicity.

C12H11I3N2O4

627.94

627.785

1949-45-7

2528

Typically exists as solid at room temperature

2.483g/cm3

678.8ºC at 760mmHg

364.3ºC

2.35E-19mmHg at 25°C

1.77

3.212

2

4

3

21

448

0

IC1=C(C(=C(C(=O)O[H])C(=C1N(C(C([H])([H])[H])=O)C([H])([H])[H])I)I)N([H])C(C([H])([H])[H])=O

GGGDNPWHMNJRFN-UHFFFAOYSA-N

InChI=1S/C12H11I3N2O4/c1-4(18)16-10-7(13)6(12(20)21)8(14)11(9(10)15)17(3)5(2)19/h1-3H3,(H,16,18)(H,20,21)

3-acetamido-5-[acetyl(methyl)amino]-2,4,6-triiodobenzoic acid

Metrizoate; Metrizoic Acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~31.25 mg/mL (~49.77 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (3.31 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

---

Solubility in Formulation 2: ≥ 2.08 mg/mL (3.31 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

---

View More

Solubility in Formulation 3: ≥ 2.08 mg/mL (3.31 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

---

 (Please use freshly prepared in vivo formulations for optimal results.)