Thyroid-stimulating hormone (TSH) release from pituitary segments triggered by thyrotropin-releasing hormone (TRH) can be regulated by 3,5,3'-triiodothyronine (T3) (10-7 M), triiodothyronacetate (10 -7 to 10 -7 M), and high quantities of iodide (10-4 to 10-5 M). Iopanoic acid exhibited no meaningful effect at the concentrations examined [2].

Administration of iopanoic acid (IOP) to pregnant rats during days 18 and 19 after conception did not influence litter size (control: 11.8±0.5 fetusesldam, iopanoic acid-treated: 11.6±0.6 fetusesldam) or day 20 Body weight (control: 3.27±0.12) g, iopanoic acid treatment: 3.42±0.20g). Iopenic acid therapy significantly reduced 5'-deiodinase (5'D) activity in interscapular brown adipose tissue (IBAT) and brain; in contrast, hepatic 5'D was not affected. At day 20, iopanoic acid-treated fetuses showed equivalent 3,5,3'-triiodothyronine (T3) level in IBAT compared with control fetuses, and 3,5,3'-triiodothyronine (T3) in brain and liver cell nuclei. '-Triiodothyronine (T3) content increased somewhat (p<0.05). However, when provided to adult rats, iopanoic acid dramatically lowered IBAT nuclear T3 content and plasma T3 levels. Iopanoic acid suppresses IBAT 5'D activity in term fetuses as effectively as on day 20 [1].

Absorption, Distribution and Excretion
Following ingestion, Iopanoic acid is rapidly absorbed, conjugated with glucuronic acid in the liver, concentrated and stored in the gallbladder, and ultimately excreted via bile.
After oral administration of Iopanoic acid, the concentration of Iopanoic acid in bile failed to reach the diagnostic concentration, at least in part due to irregular absorption.
In the presence of bile salts, the absorption of Iopanoic acid via oral administration in dogs increases, and the sodium salt form of the drug is absorbed more uniformly than the free acid.
Computer fitting showed that the bile excretion rate of sodium Iopanoic acid conforms to the Michelson-Menton equation, with a mean maximum free plasma concentration of 0.85 μmol/kg/min and a KM value of 0.253 μmol. No changes were observed in monkey blood, where it exists primarily in bile as Iopanoic acid glucuronide.
The maximum excretion of Iopanoic acid in the bile of unanesthetized dogs with bile fistulas is closely related to the excretion rate of bile salts. For more complete data on the absorption, distribution, and excretion of iodopaminergic acids (6 in total), please visit the HSDB record page. Metabolites/Metabolites… Iodopaminergic acid… and tyrosine… in dogs and humans… have been identified as ester glucuronides. …Iodopaminergic acid… previously… was found… to be converted… into… a water-soluble conjugate in cats. A re-examination of this issue determined that iodopaminergic acid and tyrosine have limited binding to glucuronic acid.

Interactions
Results showed that ether and pentobarbital anesthesia reduced the rate at which Iopanoic acid was metabolized to glucuronide in the liver compared to ether or decerebrate anesthesia. A case of poor gallbladder radiographic imaging has been reported, clearly due to the interaction between Iopanoic acid and cholestyramine in the intestine. Iopanoic acid administration led to increased sulfobromophthalein sodium (BSP) retention, possibly due to competition between Iopanoic acid and BSP for hepatic binding and excretion. Studies on influencing factors in intestinal absorption of gallbladder fluid showed that cholestyramine reduced Iopanoic acid absorption. Iopanoic acid absorption is relatively slow, with a constant excretion rate. In healthy subjects, the changes in serum thyroid-stimulating hormone (TSH) and prolactin (PRL) response to a fixed dose of thyrotropin-releasing hormone (TRH, 500 μg, intravenously) over time were investigated. Serum thyroxine (T4), triiodothyronine (T3), and reverse triiodothyronine (RT3) concentrations were assessed before, immediately after, and weekly after three daily doses of iopamidol. At the end of the intraperitoneal administration period, both basal TSH and TRH-stimulated TSH concentrations were elevated. Serum T3 concentrations were decreased.

[1]. Inhibition of iodothyronine 5'-deiodinase by iopanoic acid does not block nuclear T3 accumulation during rat fetal development. Pediatr Res. 1994 Jan;35(1):91-5.

[2]. Effects of triiodothyronine, triiodothyroacetic acid, iopanoic acid and iodide on the thyrotropin-releasing hormone-induced thyrotropin release from superfused rat pituitary fragments. Acta Endocrinol (Copenh). 1991 Oct;125(4):427-34.

Iopanoic acid is a monocarboxylic acid. Iopanoic acid contains iodine and can be used as a contrast agent in cholecystography. It is a radioactive opaque medium used as an auxiliary diagnostic tool. Mechanism of Action: Iopanoic acid inhibits thyroid function in both euthyroid and hyperthyroid patients. The secretion of 3,3'-diiodothyronine, 3',5'-T2, and 3,5-T2 induced by thyroid-stimulating hormone (TSH) in perfused canine thyroid glands was measured. Iopanoic acid (10⁻⁵ mol concentration) and iopalate (10⁻⁵ mol concentration) are both peripheral iodothyronine deiodination inhibitors, which can inhibit the secretion of 3,3'-diiodothyronine. In this study, the ability of X-ray contrast agents to inhibit the binding of (125)I-labeled T3 to nuclear receptors was investigated after in vitro incubation of rat hepatocyte nuclei or nuclear extracts and in vivo intraperitoneal injection of contrast agents. Iopanoic acid inhibited the binding of T3-(125)I in vitro.
In 21 male subjects with normal thyroid function, changes in serum TSH, thyroxine, T3, and reverse T3 concentrations were measured after oral administration of 3 g/day of iopamidol. Following iopamidol administration, TSH, thyroxine, and reverse T3 concentrations increased, while T3 concentration decreased.
Therapeutic Uses

Contrast Agent

Oral administration, used as a radioactive contrast agent in cholecystography.
Although not the preferred method, it can also be used for oral cholangiography.
The usual protocol is that the patient takes a fat-free meal after dinner, and then takes iopamidol approximately 10 hours before the scheduled X-ray examination. Immediately after the X-ray examination, the patient is given a high-fat meal and additional exposure… to assess gallbladder contraction and observe the patency of extrahepatic bile ducts. When particularly interested in the structure of extrahepatic bile ducts, the dose of iopamidol may be increased to 5 or 6 g. Dosage—3 to 6 g; the usual dose is 3 g.

A study evaluated sodium tyrosine 3g, iodoacetaminophen 4.5g, iodoacetaminophen 3g, and iodoacetaminophen 3g in 800 patients. Iodoacetaminophen was as reliable and effective as sodium tyrosine or iodoacetaminophen in cholecystography. The 3g dose produced cholecystography results as satisfactory as the 4.5g dose, with a lower incidence of spasms.
Drug Warnings

Because iodoacetaminophen is excreted by the kidneys, it is contraindicated in patients with acute nephritis and uremia.
This product should not be used in the presence of gastrointestinal disorders that impair contrast agent absorption.
Iopamidol appears to compete with bilirubin for hepatic uptake, leading to a transient increase in serum bilirubin.
Contrast-induced nephropathy is an adverse change in renal function caused by intravascular contrast agents. The incidence of contrast-induced nephropathy in the general hospitalized population is approximately 5%, and it is associated with pre-existing renal insufficiency and diabetes.
Up to two-thirds of patients with chronic renal failure may experience acute exacerbation of kidney function after exposure to contrast agents. Patients with pre-existing renal insufficiency and diabetes are at higher risk; approximately 75% of these patients develop kidney complications. The risk of contrast-induced renal failure is lower in patients with multiple myeloma, and the pathogenesis may differ from other cases of contrast-induced nephropathy. Peripheral vascular disease, hypertension, old age, and high-dose and repeated use of contrast agents may increase the risk in susceptible patients.

C11H12I3NO2

570.9354

570.8

96-83-3

3735

POWDER

2.426g/cm3

529.1ºC at 760mmHg

153 °C

273.8ºC

1.732

4.317

2

3

4

17

277

0

O=C(C(CC)CC1C(I)=C(N)C(I)=CC=1I)O

OIRFJRBSRORBCM-UHFFFAOYSA-N

InChI=1S/C11H12I3NO2/c1-2-5(11(16)17)3-6-7(12)4-8(13)10(15)9(6)14/h4-5H,2-3,15H2,1H3,(H,16,17)

2-[(3-amino-2,4,6-triiodophenyl)methyl]butanoic acid

BRN 2220381; Telepaque; Iopanoic 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 : ~100 mg/mL (~175.15 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (4.38 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 25.0 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.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (4.38 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 25.0 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.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (4.38 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 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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